UNIVERSITY OF CALIFORNIA PUBLICATIONS
IN
BOTANY
Vol. 5, No. 17, pp. 457-582, 2 figures in text, plates 55-85 April 14, 1922
INHERITANCE IN NICOTIANA TABACUM
A REPORT ON THE RESULTS OF CROSSING
CERTAIN VARIETIES
WILLIAM ALBERT SETCHELL
THOMAS HARPER GOODSPEED
AND
ROY ELWOOD CLAUSEN
UNIVERSITY OF CALIFORNIA PRESS
BERKELEY, CALIFORNIA
THE IIB»?«JY 0 C ™E
i i 1949
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BOTANY.— W. A. Setcheil, Editor. Price per volume, $3.50 (vol. 5, $6.00) ; beginning with
volume 6, $5.00. Volumes I, n, IIL TV, and IX completed. Volumes VII, VTIL and
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Cited as Univ. Calif. Publ. Bot.
VOL 5. 1912-1922.
1. Studies in Nicotiana. L by William Albert Setcheil. Pp. 1-86. December,
1912 $1.25
2. Quantitative Studies of Inheritance in Nicotiana Hybrids. I, by Thomas
Harper Goodspeed. Pp. 87-168, plates 1-28. December, 1912 „ 1.00
3. Quantitative Studies of Inheritance in Nicotian a Hybrids. II, by Thomas
Harper Goodspeed. Pp. 169-188, plates 29-34. January, 1913 20
4. On the Partial Sterility of Nicotiana Hybrids made with N. sylvestris as a
Parent, by Thomas Harper Goodspeed. Pp. 189-198. March, 1913 10
5. Notes on the Germination of Tobacco Seed. I, by Thomas Harper Good-
speed. Pp. 199-222. May, 1913 - .25
6. Quantitative Studies of Inheritance in Nicotiana Hybrids, in, by Thomas
Harper Goodspeed. Pp. 223-231. April, 1915 10
7. Notes on the Germination of Tobacco Seed. IL by Thomas* Harper Good-
speed. Pp. 233-248. June, 1915 ~ — .15
8. Parthenogenesis, Parthenocarpy and Phenospenny in Nicotiana, by Thomaa
Harper Goodspeed. Pp. 249-272, plate 35. July, 1915 - 25
. 9. On the Partial Sterility of Nicotiana Hybrids made with N. sylvestris as a
Parent. II, by T. H. Goodspeed and A. H. Ayres. Pp. 273-292, plate 36.
October, 1916 20
10. On the Partial Sterility of Nicotiana Hybrids made with N. sylvestris as a
Parent. Ill, An Account of the Mode of Floral Abscission in the F, Species
Hybrids, by T. H. Goodspeed and J. N. Kendall. Pp. 293-299. November,
1916 - - -°5
11. The Nature of the F, Species Hybrids between Nicotiana sylvestris and
Varieties of Nicotiana Tabacum, with Special Reference to the Conception
of Reaction System Contrasts in Heredity, by T. H. Goodspeed and R. E.
Clausen. Pp. 301-346, plates 37-48. January, 1917 _ 45
12. Abscission of Flowers and Fruits in the Solanaceae, with Special Reference
to Nicotiana, by John N. Kendall. Pp. 347-428, 10 text figures, plates 49-
53. March, 1918 ..... -
13. Controlled Pollination in Nicotiana, by Thomas Harper Goodspeed and Pirie
Davidson. Pp. 429-434. August, 1918
14. An Apparatus for Flower Measurement, by T. H. Goodspeed and R. E.
Clausen. Pp. 435-437, plate 54, 1 figure in text. September, 1918 _
15. Note on the Effects of Illuminating Gas and Its Constituents in Causing
Abscission of Flowers in Nicotiana and Citrus, by T. H. Goodspeed, J. M.
McGee and R. W. Hodgson. Pp. 439-450. December, 1918 ..... -
16. Notes on the Germination of Tobacco Seed. HI, Note on the Relation of
Light and Darkness to Germination, by T. Harper Goodspeed. Pp. 451-
455. April, 1919 -
17. Inheritance in Nicotiana Tabacum. I, A Report on the Results of Crossing
Certain Varieties, by William Albert Setcheil, Thomas Harper Goodspeed,
and Roy Elwood Clausen. Pp. 457-582, 2 figures in text, plates 55-85.
April, 1922 - -
Index in press.
680.5
UNIVERSITY OF CALIFORNIA PUBLICATIONS
I N
BOTANY
Vol. 5, No. 17, pp. 457-582, 2 figures in text, plates 55-85 April 14, 1922
INHERITANCE IN NICOTIANA TABACUM
I
A REPORT ON THE RESULTS OF CROSSING CERTAIN
VARIETIES
BY
WILLIAM ALBERT SETCHELL, THOMAS HARPEE GOODSPEED,
«T —
and ROY EL WOOD CLAUSEN
— .
CONTENTS page
t: I. Introductory 458
M II. Plan of the work 460
y III. Angustifolia-macrophylla series M 462
1. Parents of the angustifolia-macrophylla series 463
> . 2. Fi of the angustifolia-macrophylla series 467
3. F 2 of the angustifolia-macrophylla series 469
4. F 3 and subsequent generations of the angustifolia-macrophylla series 472
a. Stenophylla derivatives 475
c< , b. Latifolia derivatives 476
;j c. Lanceolata derivatives 478
'/. Loriifolia derivatives 478
e. Atjriculata derivatives 479
/. Sessilifolia derivatives 480
5. Summary of flower color observations in F 2 and subsequent generations 482
6. Later sowings of F 2 and F 3 of the angustifolia-macrophylla series 483
7. Crosses of derivatives with the parents 487
8. Discussion of results of the angustifolia-macrophylla series 490
3 IV. Calycina-virginica series 494
1. Parents of the calycina-virginica series 494
2. Fi of the calycina-virginica series 496
3. F 2 of the calycina-virginica series 497
4. F 3 and subsequent generations of the calycina-virginica series 499
5. Discussion of results of the calycina-virginica series 504
V. Alba-macrophylla series 504
1. Parents of the alba-macrophylla series 504
2. F t of the alba-macrophylla series 505
3. F 2 of the alba-macrophylla series 505
4. F 3 and subsequent generations of the alba-macrophylla series 507
5. Discussion of results of the alba-macrophylla series 510
458 University of California Publications in Botany [Vol. 5
PAGE
VI. General Conclusions 510
1. Origin and interrelationships of varieties of Tabacum 510
2. Methodology of Mendelian analysis in Tabacum 513
3. Mendelian heredity in Tabacum 516
VII. Summary 520
Literature cited 520
Explanation of plates 522
I. INTRODUCTORY
The inception of the work on the various species of Nicotian a
grown and bred in the University of California Botanical Garden
has already been sketched in a previous number of this series (cf.
Setchell, 1912). As stated there, the original intention was to assemble
a collection of tobacco plants simply as a portion of the outfit of the
Botanical Garden for general instruction and display. So great was
the variety and evident misapplication of the names under which the
seeds were received, however, that it seemed advisable to attempt to
determine, as definitely as possible, the status of each plant.
In this connection, the work of Comes, in particular, came under
consideration and especially his views as to the origin and interrela-
tionships of the various cultivated forms belonging to the Tabacum
group. Comes (1899, p. 4 and elsewhere) regards the numerous culti-
vated forms of tobacco as having originated in various ways from
certain fundamental varieties. He estimated that there are six of
these fundamental varieties of Tabacum, and he supposed the large
number of various and seemingly more or less intergrading forms to
have arisen through the influence of the forces of acclimatization,
adaptation, hybridization, and selection. Of these, undoubtedly, the
greater variations have been produced and perpetuated, according to
the ideas of Comes, through hybridization and selection. In his mono-
graph (1899) and in his later more exhaustive treatise (1905), Comes
has attempted to estimate just which of his six fundamental varieties
of Tabacum have cooperated in producing each one of the cultivated
"races" so far as known to him.
The statements of Comes as regards the constitution of his various
races seem to have been based on the results of morphological study
rather than upon breeding analysis. The advisability occurred to the
senior author of attempting to test Comes' hypothesis by selecting
varieties seemingly fundamental in type, and through hybridization
i^ 22 ] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 459
and selection attempting to secure constant races exhibiting various
recombinations of the parental characters. The work thus conceived
has been carried out in detail in a certain few but seemingly charac-
teristic cases. Several different crosses were made in 1909, the first
filial generations were grown in 1910, and each year since that time
has seen successive filial generations in the field.
Although the Nicotiana investigations were originally designed to
attack experimentally a comparatively simple and definite problem,
they have since been greatly amplified in scope. At the present time
three rather distinct lines of investigation are actively in progress, viz.,
1. Mendelian inheritance in N. Tabacum.
2. Inheritance of quantitative characters.
3. Studies of interspecific hybrids.
The recent appearance of bud variations in hybrid lines favorable for
an analytic study of that phenomenon has resulted in the addition
of another research project. Now it has been found that, although
seemingly distinct, progress in these separate lines of investigation is
more or less interdependent. In particular it has been found that
certain of the phenomena exhibited in interspecific hybrid populations
from crosses between N. sylvestris and varieties of N. Tabacum require
for satisfactory analysis and explanation an accurate and detailed
knowledge of the Mendelian differences which exist among the par-
ticular varieties of N. Tabacum that have been used in those investi-
gations. Accordingly in later years these studies of hybrids between
varieties of N. Tabacum, originally designed merely to test experi-
mentally the interrelationships existing among such varieties, have
been directed toward a specific Mendelian analysis of the germinal
differences existing in a selected set of varieties.
With this change in emphasis has come a full appreciation of the
difficulties of Mendelian studies in N. Tabacum. It has been very
evident that, for the most part, the character differences among varie-
ties of N. Tabacum do not rest upon a simple genetic basis; on the
contrary, they often depend upon very complex and involved Men-
delian differences; so that in segregating populations it is often im-
possible to demonstrate the existence of definite, discontinuous char-
acter classes. Not uncommonly the members of such populations may
be arranged in series connecting by imperceptible differences the most
extreme character expressions in the population.
But although complex intergrading segregation has often been
observed in F 2 , it has not been found that such complex segregation
460 University of California Publications in Botany [Vol.5
persists in subsequent generations in the hybrid lines. On the con-
trary, it has been found, as will become evident in a study of the ex-
perimental material communicated herewith, that a great simplification
occurs in the segregation in F 3 and subsequent generations, and that
continuous segregation gives way to discontinuous just as might be
expected from Mendelian theory. By observing the segregation in
the consecutive generations of hybrid lines which have become homo-
zygous in most of their loci through self-fertilization, it is possible to
obtain some idea of the Mendelian factor pairs involved in the char-
acter contrasts and of their relations to one another. It has also proved
possible by a few years of self-fertilization to establish stable lines
representing recombinations of parental characters. By investigating
the interrelations among such stable derivative lines, which obviously
should differ in fewer factors from one another and from the original
parental varieties than the parental varieties differ from each other,
it would seem possible to develop an indirect mode of attack by which
the Mendelian analysis could be refined to any desired extent. The
original plan of the investigation, therefore, having as its purpose a
demonstration of the possibility of securing by hybridization stable
derivative lines representing recombinatons of characters contained in
the parents and comparable to the numerous existing varieties of N.
Tabacum, has been diverted into a detailed study of Mendelian differ-
ences among a typical set of N. Tabacum varieties.
II. PLAN OF THE WORK
In the introductory paper the senior author has discussed the fun-
damental types of N. Tabacum, and as indicated there, has expressed
a preference .for selecting some five fundamental varieties, or species,
as representing the basal morphological elements found, or seemingly
to be detected, in cultivated races of N. Tabacum. There is no neces-
sity for discussing further, at present, the reasons for preferring the
particular types selected by us as against those of either Comes or
Anastasia (1906), since the fundamental conceptions agree sufficiently
well and the important thing has been to make a beginning in experi-
mentation by using varieties which present seemingly fundamentally
different character complexes in most characteristic form in plants
breeding true to type in the pure line. Certain reasons for selecting
a particular type or types will be discussed in connection with the
1(>L'2 |
Setchell-Goodspccd-Clausen: Nicotiana Tabacum
461
consideration of the various crosses. Besides the ' ' fundamental ' ' types,
there have been selected for crossing certain other types, possibly
fundamental, or in some cases derivative, which have been employed
for testing the inheritance of some particular character or group of
characters. All of these have been described in the first paper of this
volume.
The taxonomic problems in N. Tabacum do not appear to differ
from those presented by many other species of cultivated plants.
Barley, maize, oats, rice, wheat, among others, exhibit a similar diver-
sity of forms with more or less obvious class distinctions. In these
as in N. Tabacum it appears to be an easy task to shuffle and recombine
characters indefinitely. Clearly there can be no segregation of forms
into distinct species on genetic grounds ; the basis of speciation, if any,
must depend either upon convenience merely or what amounts to
practically the same thing, upon elevation of certain Mendelian char-
acter contrasts to a higher rank in classification than others. Since
the taxonomic problem, therefore, is not strictly a genetic one, it seems
best to follow general usage in this respect, referring all the poly-
morphic assemblage of forms to the on\ species N. Tabacum, and re-
garding the several races included thereunder as varieties of equal
rank.
The varieties employed in this series of investigations are : N.
Tabacum var. alba, U. C. B. G. 30/06, previously described by Setchell
as "White" Tobacco; N. Tabacum var. angustifolia, U. C. B. G. 68/07,
previously described by Setchell as N. angustifolia; N. Tabacum var.
calycina, U. C. B. G. 110/05 ; JV. Tabacum var. macrophylla, U. C. B. G.
22/07 ; and N. Tabacum var. virginica, U. C. B. G. 78/05, previously
described by Setchell as N. Tabacum "Maryland." In each instance
the University of California Botanical Garden (U. C. B. G.) number
contains in the numerator the accession number of the year given in
the denominator. The varieties have in the majority of cases been
grown in pure lines from the date of their receipt. In order to avoid
needlessly encumbering the text with scientific names, the varieties
mentioned above will be referred to by their varietal designations
only, and when reference is made to the whole group the species name
Tabacum will be used alone.
Three series of cultures are described in the present article : the
angustifolia-macrophylla series, which has been derived from reciprocal
crosses of angustifolia and macrophylla; the calycina-virginica series,
derived in the same way from calycina and virginica; and the alba-
462 University of California Publications in Botany [Vol. 5
macrophylla series, from alba and macrophylla. In the course of the
investigations other crosses were made between different varieties of
Tabacum and to a limited extent between other species of Nicotiana;
but the principal attention has been paid to the three crosses noted
above, and they and their progenies alone will be considered in the
present paper. It may be said at this point that the different varieties
of Tabacum cross readily with one another, giving an abundance of
good viable seed. The hybrids are uniformly self -fertile.
The methods of hybridization used need not be considered here,
because they have been described in detail by Goodspeed (1912) else-
where in this series. The particular refinements of technique which
must be employed in sowing the seed, on account of its very small size,
have also been there described. It might be well to state, however,
that the most refined methods doubtless will not prevent the occasional
appearance of a stray plant in the cultures. The danger of contami-
nation arises not only during the sowing of the seed, but also when the
bags are placed over the unopened buds. It is very easy to include a
few stray seeds under the bag, for their small size makes it almost
impossible to detect them in the coarse, sticky indumentum of the
plant. In spite of these obvious difficulties, however, the number of
plants that have certainly been strays has been very small. Their
rare occurrence indicates clearly that the technique employed has been
very successful.
III. ANGUSTIFOLIA-MACROPHYLLA SERIES
This series has received the most attention since the parents are
so distinctly different, and the results have consequently been more
complex than those which have followed the crossing of any other pair
of Tabacum varieties. As will be demonstrated below, F 2 seemed at
first hopeless in its variety of segregation. Later generations, however,
exhibited so much less, or so little variety in their segregation products
that it was easy to obtain new permanent combinations of characters
or "fixations." Certain of its segregants have been followed out to
F 7 , and have also been crossed back on the parents which they most
closely resembled.
Six successful crosses were made. Of these H 2 and H 3 had macro-
phylla for the male and angustifolia for the female parent, while H 4 .
H 5 , H 15 , and H 16 were reciprocal crosses. As a matter of convenience
I 922 ] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 463
the generations later than F x were grown only from H„ and H 4 , the
larger number from H 4 . The predominance of H 4 in the later families
selected for the continuation of the work was not, however, due to any
especially different behavior evidenced in that particular series.
1. PAEENTS OF THE ANGUSTIFOLIA-MACROPHYLLA SERIES
By selecting angusti] 'alia and macrophylla for crossing, two varie-
ties were obtained which resemble each other in height and general
habit, but which differ strikingly in leaf and flower characters. The
differences are sufficiently great to lead one to regard them as belong-
ing to different species ; in fact, all five Tabacum varieties selected by
us as possibly fundamental differ sufficiently among themselves to be
regarded as species in the Tabacum section rather than as varieties.
It is not our intention, however, to emphasize this point, since any
discussion would of necessity lead to a general survey of all the known
varieties and races at present included under Tabacum. If, however,
these five, viz., angustifolia, macrophylla, " Cavala," Maryland, and
"Brazilian" (cf. Setchell, loc. cit.) could be considered by themselves
as wild plants, it seems to us that any taxonomist of the present day
would certainly award to each of them the^pank of a separate species.
These considerations should be borne in mind in estimating the signifi-
cance of the results obtained through crossing.
Angustifolia, U. C. B. Cr* 68/07, is a variety which has long been
known and which is represented in our breeding experiments by a
pure line very closely approximating the type. It has been figured
and discussed by one of us (Setchell, loc. cit., p. 9, pi. 7). The photo-
graph given there is of a young plant just coming into flower and
consequently does not represent the habit of the plant in full blossom
or in fruit, after the full number of laterals is developed. A plant
in the height of its vigor is represented in plate 55, figure 1. In
stature angustifolia belongs to the low corymbose group of Tabacum
varieties, which also includes the forms bred in the University of Cali-
fornia Botanical Garden under the names calycina and macrophylla,
and which is in decided contrast to the tall, more "racemose" (al-
though these may be "corymbose" at the top) forms such as alba and
virginica.
In height angustifolia varies from 75 to 120 cm. The central axis
develops its corymbose panicle of short racemes first, but it is usually
soon overtopped by the successive laterals developed basipetally, each
464 University of California Publications in Botany [Vol. 5
lateral, in turn, developing a corymbose cluster of racemes, rising
more or less above its predecessors.- The result is that the whole plant
has the short corymbose habit mentioned above. The stems and
branches of angustifolia are comparatively slender, being much more
slender than those of macrophylla, or those of any other of the Tabacum
varieties except those of calycina, which are very similar.
The leaves of angustifolia are alternate and distinctly and moder-
ately long, petiolate. The blade of the lower leaves is ovate-lanceolate,-
tapering above to a long, curved point, more or less conduplicate below
and with the rounded bases unequal. Above, the leaves are less con-
duplicate, more so even at the base, with the petiole shorter, while the
uppermost (bracts) become almost sessile and narrowly lanceolate even
to almost linear in outline. The normal petiole is naked at the base
and in the middle portion, but the base of the blade is slightly and
narrowly decurrent along the upper portion. Occasionally a petiole
shows a narrow wing throughout its length and at t'imes the petioles
of all the leaves on certain plants are more or less winged, but the
majority of the plants have naked petioles (cf. also Good speed and
Clausen, 1917, p. 306, pi. 46, right-hand figure). The leaves of angus-
tifolia have also a very characteristic drooping habit, much more pro-
nounced than in any other Tabacum variety except calycina. In older
plants, after capsule formation lias well advanced, all the leaves are
hanging obliquely downwards.
The flower of angustifolia is distinctive and differs in details of
shape and color from that of any other Tabacum variety, and especially
from that of macrophylla. The general shape of the flower is that of
all the Tabacum section, but the corolla is much more slender and more
gradually infundibuliform than that of any of the other varieties re-
ported here. The calyx is broadly campanulate, prolonged above into
5 long, but unequal, linear-lanceolate, pointed lobes, of which one is
longer than the remaining four and gives the calyx a zygomorphic
appearance. The corolla is narrow and tubular below the middle,
expanding rather gradually and evenly above into a conical infundi-
bulum which bears the spreading, deeply 5-lobed limb at its summit.
The length of the tube of the corolla is about 6 cm. and its greatest
diameter about 7 mm. The limb of the corolla, at first erect (opening
bud), then horizontal, finally becomes somewhat deflexed and measures
about 3 or 3.5 cm. across. It is divided almost to the tube into 5 lobes
which are ovate-lanceolate with long, narrow, tapering tips. The lobes
of angustifolia are much longer and have narrower tapering tips than
1922] Setchell-Goodspeed-Clausen : Nicqtiana Tabacum 465
those of any other Tabacum variety, and in this respect are in direct
contrast to those of macrophylla. The lohes are unequal and give a
slight suggestion of zygomorphism to the corolla. The stamens are
inserted on the lower portion of the tube and are usually slightly ex-
serted in anthesis. The pistil possesses the usual 2-celled ovary, long,
slender style, and thick, slightly bilobed stigma, more or less exserted
in late anthesis, characteristic of the genus Nicotiana. The color of
•the corolla is a light, though lively, pink, much lighter than -the red of
macrophylla. The capsule at maturity is slightly flattened longitud-
inally, is broadly lanceolate in profile, tapers above into an acuminate
apex, and is about 25 mm. high and 8 to 9 mm. thick. It is the most
slender of all the capsules borne by the various Tabacum varieties
and in decided contrast to the stout capsule of macrophylla.
In plate 55, figure 1, is illustrated a plant of angustifolia at the
height of its blooming period. Typical features of the plant are shown
in the line drawings of plate 56. Photographs of typical leaves are
shown in plate 58, where they may be compared with photographs of
the leaves of macrophylla. Photographs of the flowers are reproduced
in plate 60, where they may be compared with those of macrophylla
and of the hybrids between these two varieties.
Macrophylla, U. C. B. G. 22, 07, has already been discussed and
figured by one of us (cf. Setchell, loc. cit.)". The original seed was
obtained from Comes, but the plants do not correspond to his figures
(cf. Comes, 1899, pi. VIII) either as to habit or sh^pe of leaf. They
differ also from his description in these same respects. The flower,
however, agrees, and it seems best to retain for it the name under which
we have cultivated it.
The habit and height of macrophytta are both very similar to those
of angustifolia. The habit is low corymbose, the central axis bearing
a panicle of corymbose racemes and the laterals arising one after the
other bearing similar inflorescences and equaling or overtopping the
central axis. The stems and branches are stouter than those of angus-
tifolia, however, and this, together with the broader, more solid looking
leaves which do not droop so much as those of angustifolia, give a
mature plant of macrophylla a much more robust appearance than is
the case with a mature plant of angustifolia. The plant figured in the
first number of this volume (pi. 6) was young. An older plant shown
herewith on plate 55, figure 2, is in full blossom and beginning to ripen
its capsules, and gives a better idea of the habit of a well grown plant.
466 University of California Publications in Botany [Vol. 5
The leaves of macrophylla are sessile by a partially clasping base
and possess two basal lobes partially clasping the stem. The general
shape is obovate, the widest portion being above the middle. The
leaves taper gradually to the broad clasping base below and abruptly
to a narrow more or less acuminate tip above. The surfaces show the
secondary veins branching at a more obtuse angle than do those of the
leaves of an gusti folia. The color of the leaves is a dark green in
macrophylla and more of a yellowish green in angustifolia. In every
way, then, the leaves of the two parents differ from each other as much,
in fact, as do the leaves of many species.
The flowers of macrophylla, while of the same general type as those
of angustifolia, differ in details of shape and color. The flowers of
macrophylla are about 4 cm. long. The calyx is broadly ovate in pro-
file, deeply cut into 5 broad and somewhat unequal lobes. The corolla
tube is stout cylindrical (about 5 mm. in diameter) below, broaden-
ing suddenly into a stout infundibulum above (about 10 mm. in diam-
eter). The limb is at right angles to the tube, is about 23 mm. across,
and is more or less pentagonal with 5 shallow sinuses. The color of
the corolla is deep red fading to an almost lilac tint after anthesis.
On the limb are 5 triangular lighter areas, one having the narrow
apex at each sinus and the broad base at the top of the tube. In the
much darker color, in the broader tube and stouter infundibulum, and
in the barely appreciable lobing of the limb, the corolla of macrophylla
is the antithesisJpf that of angustifolia. In stamens and pistil, the
flower of macrophylla shows little variation from that of angustifolia.
The capsule of macrophylla is broadly ovate, tapering abruptly to
a mucronate tip. It is about 2 cm. high and about 1.5 cm. in diameter,
contrasting very decidedly with the comparatively slender capsule of
angustifolia.
A typical plant of macrophylla is shown in plate 55, figure 2.
Typical features of the plant are shown in line drawings in plate 57.
Photographs of leaves are reproduced in plate 58, where they may
be compared directly with those of angustifolia. In plate 60 its flowers
may be compared directly with those of angustifolia and with those of
the hybrids.
It has seemed best to call attention to the characters of and differ-
ences between these two varieties, parents in the first set of crosses to
be discussed, in order that the behavior of their hybrid progeny may
be clear. In height and habit there is a close agreement, but in leaf,
flower, and fruit there are sufficient differences to mark them as sep-
arate species.
1922]
Setchell-Goodspecd-Clausen: Nicoiiana Tdbacum
467
2. F x OF THE ANGUSTIFOLIA-MACROPHYLLA SERIES
In late July of 1909, some 7 crosses were made between angusti-
folia and macrophylla, 6 of which, as stated above, were successful.
H 1; H 2 , and H 3 , as they were designated, involved angustifolia as the
female plant, while H 4 , H 5 , H 15 , and H 16 were reciprocals. No seed was
obtained from H 1; but all the other 6 crosses gave a fair yield. The
usual care (cf. Goodspeed, loc. cit., pp. 129-131) was taken in cleaning
and sowing the seed. This was done in the spring of 1910, germination
was good in all cases, and 337 plants, distributed as follows, came to
maturity and seed bearing. The family of H 2 had 56, H 3 had 60, H 4
had 47, H 5 had 58, H 15 had 55, and H 16 had 61 plants.
A survey of all these plants showed in general a remarkable uni-
formity in habit. A certain amount of difference was to be detected
on careful scrutiny, but little if any greater than that which is ex-
hibited among a large number of individuals of one or the other parent.
In height, F 1 showed exactly the same variation as the parent, the
central axes varying from 65 to 145 cm., but largely varying from 90
to 120 cm., while the laterals rose to 150 cm. Some rows showed uni-
formly higher, others uniformly lower plants, the differences probably
being due to different soil and water conditions. The habit (see pi. 61)
was low corymbose and the general appearan^ as to stoutness seemed
more or less intermediate, between the two parents. The leaves in
shape, size, etc., very closely resembled those of angustifolia. There
was some appreciable variation in the leaves, however, aild often con-
siderable variation on the same plant, a characteristic of angustifolia
which has already been mentioned. Plate 59 reproduces photographs
of different types of leaves obtained from F x plants. The blade is
| broadly elliptical ovate with the lateral veins at an obtuse angle, much
as in macrophylla. The base is rounded, or even slightly cordate in
some leaves, while the tip is more blunt. These characters seem, at
least, to indicate an influence of macrophylla. The leaf, however, is
distinctly petiolate, but the petiole is not so long as in angustifolia.
The petiole is definitely winged and the wings are expanded at the
base into auricles, which are often triangularly decurrent along the
internode of the stem. This wing is usually present in all the plants
of F 1; but some leaf or leaves on a plant may lack it, and in some
plants it is only slightly developed, or at least, is without auricles.
The wing was from 5 to 7 'mm. wide on some leaves.
The leaf of lOFiH^P, represented in plate 62 even more closely
resembles the typical leaf of angustifolia. The wing along the mar-
468 University of California Publications in Botany I VoL - 5
gins (or edges) of the petiole is narrow and is prolonged as a slight
ridge to the internode and is decurrent (?) or can be traced as it bends
sharply downwards. Such wings are, at times, found in pure bred
angustif olia plants. This leaf, then, resembles the angustif olia leaf
fairly closely, but differs from its ordinary expression in the more
tapering base, in being less distinctly conduplicate, in tapering more
abruptly toward the tip, in having shorter petioles and in having more
of a wing on the margins of the petiole.
The flower of F x (see pi. 60) resembles that of angustifolia more
than that of macrophylla. The color is deep pink, decidedly of a
deeper shade than is the flower of angustifolia, yet far from the red
of macrophylla and in a way intermediate between the two. There
is no trace, on the limb of the corolla of F 1} of the 5 white triangle-
shaped areas so characteristic of the limb of the corolla of macrophylla.
The infundibulum, while possibly slightly stouter than that of the
flower of angustifolia, is not so stout as that of the flower of macro-
phylla. In length the flower of F x averages about 4 to 4.5 cm. as
against an average of 6 cm. in angustifolia, and of 4 cm. in macro-
phylla. The tube averages about 3.5 to 5 mm. in diameter below, as
contrasted with 2.5 to 3 mm. as an average in angustifolia and 5 mm.
in macrophylla. %The infundibulum in the corolla of F t , while neither
abrupt nor so stout as tjnat of the flower of macrophylla, is noticeably
more abruptly enlarged and stouter than that of angustifolia. The
limb of the corolla in f\ averages 2.5 to 3.25 cm. in greatest diameter,
while that of angustifolia averages 3 to 3.5 cm. and that of macrophylla
averages about 2.3 cm. in greatest diameter. The lobes of the corolla
in Fj are about half the width of the limb from tube margiflfto extreme
tip of lobe, while in angustifolia they are about two-thirds of thi
in macrophylla they are only one-third or even less. The lobes,
are decidedly broad at the base, particularly so as compared with tneir
length. In general, then, the corolla of F 1} while closer to that of
angustifolia, shows by its stouter tube, more abrupt and more swollen
infundibulum, intermediate spread of limb, less deep lobing, shorter
and broader lobes, and deeper shade of pink, definite influences of
macrophylla also.
The capsule of F x is broader than that of angustifolia, but nar-
rower than that of macrophylla. There is greater variability in hori-
zontal diameter in the capsule of F 1 . The flower and fruit of F^
then, although no careful biometric study has been made, are inter-
mediate between those of the two parents, yet incline more toward
angustifolia than toward macrophylla.
1 922 1 Setchell-Goodspeed-Clausen : Nicotiana Tabacum 469
In general, then, a survey of F 1 shows throughout a series of ten
different families a uniformity of individuals as great as that exhib-
ited in either of the parents. Some few slight differences exist among
individuals both of F x and of the parents which may possibly be re-
ferred to lack of a completely homozygous conditon in the parents.
In characters in which the two parents differ, whether in color of
flower, quantitative corolla character complexes, capsule character com-
plexes, or leaf character complexes, the Fj hybrid exhibited through-
out a character expression intermediate between that of the two
parents.
3. F 2 OF THE ANGUSTIFOLIA-MACKOPHYLLA SEEIES
In 1911, there were selected as parents for the F, 13 plants from
H 2 and 12 from H 4 . Twenty-one families of approximately 50 plants
each were set out in the field. On account of the great diversity shown
in these populations, it was found impossible to study individually
each of the thousand plants grown ; consequently particular attention
was paid to only 5 families from each hybrid. The other families were
gone over carefully, but nothing notably different was found in their
behavior. All fifty plants survived in each family except in the last,
viz., 11F 2 H 4 P 43 , where only 48 came to maturity. There were then
498 plants of F 2 under more careful observation, representing both
the cross and its reciprocal, with about 550 remaining for only casual
examination.
As might have been expected, there was a great variety of^ plants
resulting and segregation as to differences in combination of characters
of flower, fruit, and leaf was little short of bewildering. An attempt
was made to study and Arrange these combinations, but it .was found
to be impossible. A eareful survey, however, was aaade./of the popu-
lations and a tabulation of characters was attempted. "^orae 16 fairly
readily separable types, based on leaf characters, were distinguished,
but between these closely approaching types others were to be found
of intermediate and overlapping character. One each of the types
selected was drawn, and these drawings are reproduced in plates 63
to 78.
A glance at these plates, which were carefully drawn to scale, will
show something of the nature of the combinations of characters of the
two original parents. Type 1 (pi. 63) shows a close approximation,
yet not an absolute reproduction, of angtistifolia, while type 16 (pi. 78)
in a similar way is a close approximation to macrophylla. The other
470 University of California Publications in Botany [Vol.5
14 types (pis. 64 to 77) are clearly intermediates approaching one
parent more than the other, but types 12, 13, and 14 (pis. 74 to 77,
inclusive) are decidedly different from either as to leaf, at least, and
type 10 (pi. 72) is of another altogether different form, although all
of these leaf shapes are connected to a greater or less extent into one
series of more or less gently intergrading forms.
As to the shape and dimensions of the corolla there is to be found
a similar series of intergrading forms from the slender corolla tube
with gradually expanding and slightly swollen infundibulum and
deeply lobed limb of type 1 (pi. 63) to the corolla with stout tube,
abruptly and considerably swollen infundibulum with slightly lobed
limb of type 16 (pi. 78). In color the corollas vary from the light
pink of angustifolia to the red of macrophylla and three shades are
at times fairly readily distinguishable, the light pink of angustifolia,
the deep pink of F 1? and the several nuances of the red of macrophylla.
The capsules also show various combinations from the slender
gradually attenuated capsules of angustifolia to the stout, swollen,
abruptly upwardly attenuated capsules of macrophylla. Both cap-
sules and corollas approaching one parent may be found with leaves
more closely approaching the other parent. In stature and habit the
plants of all the 21 families were reasonably uniform and agreed in
general in these respects$-wkh the parents and F u there certainly being
no greater amplitude of'variation in thes^respects than was to be
found in the parental types.
Among the great variations, two characters seemed to stand out
fairly V clearly for rough statistical enumeration, viz., color of the
corolla and the possession, or lack, of a petiile. Numerical data for
these characters are given in table 1. Some can 1 was taken to obtain
a careful -rbnsus of the families as regards each of the characters. As
regards colorsjudf was, as noted before, possible to distinguish three
shades, or sets of shades, which were designated as light pink, pink, 4ud
red. In practice, however, it was usually difficult to distinguish the
two shades of pink from each other. The red gave very little trouble.
In attempting to classify the plants of F 2 with respect to type of
leaf base, more difficulty was experienced because of the variety of
forms which were produced and the degree of intergradation which
existed between forms. In judging the presence or absence of petiole,
therefore, in these populations, the classification is faulty because of
lack of knowledge of the genetic constitution of the various distinct
forms and those which grade into them. In table 1 the plants are
1922] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 471
thrown into the petiolate class if they were distinctly narrowed at the
base, and whether naked or winged.
In F 2 , then, there appears to be simple Mendelian inheritance in
only one pair of the original character contrasts of the parents, namely,
red versus pink corolla color. Here the hybrid is intermediate
and F 2 segregates sharply into pink and red in the ratio 3 pink : 1 red.
Within the pink class there is a more or less evident segregation into
2 pink : 1 light pink, but the shades intergrade so that no distinct line
of demarcation exists between the classes. As respects leaf base char-
acters, the segregation is so complex that no reasonable genetic analysis
is possible. The numerical data for this latter character presented in
table 1 are of value only in that they indicate a close agreement in
segregation among F 2 families, thereby furnishing a rough statistical
demonstration of the equivalence of the several families. The more
definite data on leaf base characters are derived from generations
subsequent to F 2 .
TABLE 1
CLASSIFICATION OF F 2 PLANTS OF THE ANGUSTIFOLIA-MACROPHYLLA SERIES
ACCORDING TO COROLLA COLOR AND LEAF BASE CHARACTERS.
Family
i
Garden
\ Corolla Color ^
Leaf Base
Designations
Numbers /
red
pink
light pink
petiolate
non-petiolate
A
11F 2 H 2 P,
12
23
14
42
7
B
11F 2 H 2 P 3
14
25
10
30
20
C
11F 2 H 2 P 6
13
21
15
34
14
D
11F 2 H 2 P 7
7
21
22
35
15
E
11F 2 H 2 P 13
15
20
14
30
20
F
11F 2 H 4 P 2
13
28
7
32
17
G
11F 2 H 4 P 3 5
12
29
8
' 35
„_~/"l4
H
11F,H
31
31
17
K
6
27
15
38
10
Totals
113
240
137
339
152
472
University of California Publications in Botany
[Vor,. 5
4. F 3 AND SUBSEQUENT GENERATIONS OF THE ANGUSTIFOLIA-
MACROPHYLLA SERIES
From F 2 of H 2 and H„ 20 plants were selected for further ex-
perimentation and families of 25 were determined upon as the unit.
In all except four, the families of 25 each were successfully raised.
Of one of the four only 14 plants were obtained, which were all that
germinated, while in each of the other three families 24 plants were
reared to maturity. Altogether, then, 486 plants were raised of the
F 3 during the season of 1912. It was the intention to grow from each
of the selected types, as drawn for illustration. Fifteen of the families
from the type parents were successfully reared, but, in some way or
other, the seed of type 4 (10F 2 H,P 7 P 1S ) was not to be found, and,
unfortunately, no note had been made as to whether or not any seed
was produced. No complete sterility, however, was noticed in any
members of F 2 of either H 2 or H 4 , and the presumption is that F, seed
of type 4 must have been lost in harvesting.
The variation within each family was decidedly less than that of
the families of F 2 . Of the 20 families reared wholly or in part, 4
families were very^^arly uniform, varying in minor details only.
Five families segregated only in corolla^olor, 4 segregated only in
leaf base characters, and the remaining 7 segregated .both in corolla
color and leaf base characters. In table 2 are summarized the data
as to gross behavior of thlse families of F v In those families grown
in F 4 and subsequent generations, a definite attempt was made to fix
the original characters of the F 2 type selection in a pure line. The
genealogical relation of these selected lines to each other is shown in
the chart reproduced herewith. The letters, A, B, C, etc., correspond
to thej<\ family designations noted in table 1, and the numbers refer
to type selection numbers corresponding to the type illustrations in
plate 63 to 787 or, in tne case of types 17 to 21, corresponding to those
types as described in the succeeding accounts of the later generations.
IF A
1922]*
Setchell-Goodspeed-Clausen: Nicotiuna Tabacum
473
TABLE 2
F 3 FAMILIES OF THE ANG U S TI FOLIA-MA CROPH YLLA SERIES.
Type
Nos.
Garden
Numbers
No. of
plants
in fam-
ilies
Results in F3
1
^ ■• T "X XX X"» X"»
IIF2H2P7P49
25
Segregated both as to leaf and flower color
2
1 i TP tt n n
1H , 2 H2P3P30
25
Segregated both as to leaf and flower color
3
1 1 TP TT Tl "Fl
HF 2 H 2 P 3 Pi4
14
Segregated only as to leaf
5
-f 1 T71 tt xi n
11F2H4P41P14
24
Segregated both as to leaf and flower color
6
-< 1 r\ XT Tl T*
IIF2H4P2PJ8
25
Uniform except as to length and development of
wing of petiole
7
IIF2H2P13P48
25
Uniform both as to leaf and flower color
8
11F 2 H 2 P 3 P 4 1
25
Segregated as to leaf only
9
IIF2H4P41P8
25.
Segregated both as to leaf and flower color
10
HF^PwPlT
24
Segregated only as to flower color
11
11F2H4P4!?!)
25
Segregated onlyfe to flower color
12
HF 2 H 4 P 4 lPl2
25
Segregated only as to flower color
13
HF2H2P3P44
25
Segregated only as to flower color
14
IIF.HP.Pm
25
Segregated both as to leaf and flower color
15
IIF2H2P3P10
25
Uniform, slight variation in tint and lobing of corolla
16
11F 2 H2P 3 P 8
24
Segregated only as to leaf
17
11F 2 H 4 P 36 P 2 7
25
Segregated only as to flower color
18
11F 2 H 4 P 35 P 38
25
Segregated both as to leaf and flower color
19
11F 2 H 4 P»P«
25
Segregated both as to leaf and flower color
.^-^
20
HF2H4P40P44
25
^Uniform, close to macrophylla
21
HF2H4P41P29
25
Uniform, close to angustifolia
474 University of California Publications in Botany [Vol. 5
T
In F, primary selection for parents of subsequent generations was
based upon the type of leaf borne by the plant, flower color being
followed as a secondary matter. In order to systematize the discussion
concerning P 3 and subsequent generations, six general types have been
selected and named and the discussion of the families has been grouped
Pi 1909
Fi 1910
Fa 1911
Fa 1912
F* 1913
Fs 1914
Fs 1915
F? 1915
Fig. 1. — Chart showing the relationships of the various families of the angusti-
folia-macrophylla series. The different F a hybrids are connected with their female
parents; no seed was secured from H,. The F, family designations correspond to
those given in table 1, and the numbers in later generations are the type numbers
under which the populations are described in the text. F 4 and F 5 of type 12a were
grown in 1914 and 1915 respectively.
under these headings. The six general types selected and the names
given them are as follows :
a. Stenophylla derivatives. As a series these approximate very
closely in leaf shape to angustifolia. The distinguishing feature of
this series is the possession of a distinct, long petiole.
b. Latifolia derivatives, which are characterized by the possession
of a broad leaf with a petiole shorter than that of angustifolia. The
petiole in these types is more or less winged.
c. Lanceolata derivatives, which are characterized by the posses-
sion of a lanceolate leaf like that of type 13, illustrated in plate 75.
This is a non-petiolate form.
d. Loriipolia derivatives, characterized by possession of long leaves
with very narrow blades. The type specimen, type 12, is illustrated
in plate 74. This also is a non-petiolate form resembling the lanceo-
lata derivatives, from which it differs in the extreme narrowing of the
blade.
*
1922] Setchell-Goodspeecl-Clmisen: Nicotiana Tabacum 475
e. Auriculata derivatives. The typical form of leaf is that of
type 10, illustrated in plate 72. The leaf blade of this form is char-
acterized by an abrupt contraction of the blade at the base, nearly, if
not quite, to the midrib. Clasping auricles, from which the name is
derived, are usually present in this form.
/. Sessilifolia derivatives, of which the leaf of macrophylla may
be taken as the type. These derivatives are non-petiolate, as the name
indicates.
a. Stenophylla derivatives
Type 1, as may be seen from the drawing of F 2 .(cf. pi. 63), seems
very close to angustifolia, and had light pink flowers. There were 25
plants of 12F 3 H 2 P 7 P 49 , the leaves of which were carefully noted ; bujj
one passed its flowering stage too early to be judged, so that the colors
of the flowers of 24 only are known. Sixteen plants had stenophylla
leaves very nearly of type 1, but the extent of the wing structure varied
somewhat. The remaining 9 had lanceolata leaves of type 14. In
flower color the segregation ratio noted was 5 red : 19 pink. No further
generations of this line were grown.
Type 17 was not selected for illustration in F,, but was a plant
very close to angustifolia. It had, however, somewhat narrower leaves
and deep pink flowers. The 25 plants of 12F„H 4 P :!5 P 27 were uniform
and like the F 2 parent except as to flower color ; 3 were red and 22 were
deeper or lighter pink. This line was not grown through further
generations.
Type 21, also, was not selected for illustration of the F 2 plant, but
was chosen later for perpetuation because of its extremely close agree-
ment with angustifolia. The F 3 , 12F 3 H 4 P 4 P 29 , consisted of 25 vigorous
plants which seemed to be uniform to the finest detail and agreed in
every respect with plants of angustifolia. There were noticed in the
plants of this family peculiar fimbriae attached to the corolla, or split
corollas, or, in one instance, a split hose-in-hose flower such as occurs
at times also in pure angustifolia. This type seemed toHSe a pure
recombination of the characters of angustifolia.
Type 21 was continued through tf the individuals in the several
families. In 1913, 94 plants of F 4 wfere grown ; in 1914, 85 plants of
F, ; in 1915, 10 plants of F 0 ; and in 1916, 8 plants of F 7 . All these
populations closely resembled one another as to individuals as well
as those of the F 3 and the F 2 parent. They are all so close to angus-
476 University of California Publications in Botany [Vol.5
tifolia as to be practically indistinguishable from it. This line may
be regarded, therefore, as a stable derivative very closely approxi-
mating angustifoUa in all its characters.
b. Latipolia derivatives
Type 2 (cf. pi. 64) approached in F 2 fairly near to some of the
variations of F x (cf. pi. 62). It might be regarded as a stenophylla
derivative possessing an unusually luxuriant development of the wing
of the petiole, but it seems more reasonable to classify it as a latifolia
derivative exhibiting marked narrowing at the base of the lamina, such
as is shown in lajsTceolata derivatives. The flower was designated as
light pink in the notes taken at the time of flowering. The leaves of
F 3 showed segregation through a considerable range, 6 being close to
the latipolia type of F 1; 6 to the latipolia type of its F 2 parent
(type^2), 8 were sessilipolia leaves approaching in type those of mac-
rophylla, and 4 were auriculata leaves of type 10. In 13 the flowers
were noted as light pink, in 11 as pink, and in 1 as red. No subsequent
generations of this population were grown.
Type 3, in F 2 , had (cf. pi. 65) a distinctly ovate lanceolate leaf
with a short fairly broadly margined petiole. The flowers were light
pink. F 3 , 12F 3 H 2 P 3 P 14 , amounted to 14 germinations,, all of which
developed, although slowly, into healthy, normal appearing plants.
The flowers were all the light pink color of the F 2 parent, agreeing
with those of angustifoUa; but varying somewhat in shape and size.
The leaves were of various shapes, 4 were distinctly petiolate, while
10 were sessile. Of the 4 petiolate plants the petiole of 1 was naked
and of 3 more or less winged. Of the 10 sessilipolia plants, 9 were
very similar to type 11, but 1 was rather longer and narrower, although
otherwise approaching the same general shape. No further generations
from this line were grown.
Type 5 in F 2 (cf. pi. 67) resembled F 1 most nearly, but the winged
petiole ^i&wghort and the corolla tube slightly stouter. The flower
color was pink. Of 12F 3 H 4 P 41 P 14 , 24 plants were grown. Of these
23 had leaves alm\j|£ exactly like those of the F., parent, but 1 had
leaves more nearly like aurictHlata o f 'J &££jLX<4- P L ^Q)- Of the 24
plants, 16 had flowers of various grades of pink while 8 had red flowers.
This line was not grown in subsequent generations.
Type 6 was represented in F 2 by a plant which resembled F, in
having a winged petiole to the leaf and a pink flower. It is well fepre-
1922]
Setchell-Goodspeed-Clausen: Nicotiana Tabaciim 477
sented on plate 68. In the 25 plants of 12F 3 H 4 P 2 P 18 , the height,
habit, flower shape, and flower color were close to, if not identical with,
those of the F 2 parent. As respects leaf base characters, 14 were
latifolia of type 6, 4 had long, naked petioles, 3 had short, naked
petioles, 1 had a long, winged petiole, and 4 were auriculata plants
nearly of type 10. This seems like a considerable segregation, but the
leaves are of only two generic types, viz., petiolate and non-petiolate.
In subsequent generations selection was made in one line for latipolia
leaves of type 6, and in the other for auriculata leaves of type 10,
called type 6a to indicate its derivation.
Of type 6 as thus established 100 plants of F 4 were grown in 1914 ;
100 plants of F 5 (50 each from 2 different parents) in 1915; 20 plants
of F 6 in 1915; and 20 of F 7 in 1916. All the individuals thus grown
were constant to latipolia of type 6 as originally selected.
Of auriculata of type 6a, similarly, 100 plants of F 4 were grown
in 1913 ; 94 of F 5 in 1914 ; 20 of F, in 1915; and 20 of F 7 in 1916. All
these plants were uniform and true to auriculata of type 6a, very
close to auriculata of type 10. In both th^ types we have definitely
obtained stable recombinations of germinal elements exhibiting char-
acters different from those or the parents.
F 3 of type 7, 12F 3 H,P 13 P 48 (cf. pi. 69), consisted of a family of
25 plants, all vigorous except one (P 17 ), which was set out in the field
later and developed into a "runt," as often happens with such later
plantings. All the plants agreed well with one another in height and
habit except the ' ' filler, ' ' and all agreed in inflorescence, flowers, and
leaves. There were some variations in size and lobing of the limb of
the corolla, indicating possibly minor segregation, but in all general
characters there was uniformity to a large degree. The plants agreed
well in all characters with the F 2 parent, and also with the F 4 parent.
The color of the flower was light pink, the petioles of the leaves varied
somewhat in length, were distinctly and more or less broadlya&iged,
and the blade was heart-shaped, at least at the base in the lower leaves.
In all respects these characters were no more variablejthan they were
found to be in F 4 .
Type 7 continued to breed true in subsequent generations. It was
grown in 1913 (100 plants, F 4 ), 1914 (^families of 50 plants each,
F s ), 1915 (10 plants, F 6 ), and 1916 (10 plants, F 7 ). All were uni-
form as to leaf and flower color. Type 7 is very close to the type of
F 4 and to type 6 described above. It, too, evidently represents a stable
recombination of germinal elements derived from both parents.
478 University of California Publications in Botany [Vol. 5
Type 9 resembles type 5, but had iu F 2 a very short winged
petiole and elliptical lanceolate blade. It also had pink flowers. F.,,
12F 3 H 4 P 41 P 8 , consisted of 25 plants, 18 of which showed latifolia
leaves of type 9, but 7 had sessilifolia leaves of type 14 (cf. pi. 76).
Twenty-one had pink (or light pink) flowers and 4 had red. No
further generations of this line were grown.
Type 19 was an F 2 plant of which no drawing was made, but it
resembled ¥ 1 (cf. pi. 62), having broadly ovate leaves with a long
and broadly winged petiole and pink flowers. F 3 , 12F 3 H 4 P 35 P 43 , con-
sisted of 25 plants, 6 of which had sessilifolia leaves of type 16 (cf.
pi. 78) or nearer, perhaps, to those of macrophylla, while 19 had
latifolia leaves of type 19. In 5 plants the flowers were a somewhat
darker red than they were in the other 20. This line was not followed
further.
c. Lanceolata derivatives
Type 13 is similar to type 12 described below, but the leaves of the
F 2 plant were more lanceolate and broader and the flowers were lighter
pink. The 25 plants of 12F 3 H 2 P 3 P 44 were uniform and like F 2 except
in flower color. Four were red, 19 decidedly pink, and 2 inclined to
light pink. The line was not grown in subsequent generations.
d. Lariifolia derivatives
Type 12, as shown in plate 74, differed very decidedly in leaf shape
from either parent. The long linear-lanceolate leaf had the long taper-
ing curved tip of angustifolia, but the blade tapered below, making
practically a new type. The flowers were like those of angustifolia
in shape but were pink. The 25 plants of F 3 , IZFJIJ*^?^, were
exact duplicates of F 2 as to habit, leaf, and flower shape, but 10 had
red and 15 had pink flowers of various shades, mostly dark. None
seemed as light pink as angustifolia.
Thw*is the most interesting of the types carried through subse-
quent generations, representing, apparently, a new combination of leaf
characters. OT^^the pink flowering F 3 plants was chosen for seed
and the designation, type 12, retained for this and its progeny, while
the designation. 12a, was gjven to one of the red flowering F. plants
also chosen for seed.
Type 12, as thus limited to the pink flowered plant, gave scanty
germination and few plants for F 4 in 1913. Apparently , it was still
varying slightly in color within the pink shades, althouglwfairly uni-
1922 ] Setchell-Ooodspeed-Clausen: Nicotiana Tabacum 479
form except for one aberrant ( ?) plant of a decidedly lighter shade.
Two "normal" parents of F 4 gave 88 and 100 plants of F 5 in 1914,
which were uniform and of a bright pink color. In 1915 P 0 showed
10 plants, and in 1916 F 7 also showed 10 plants, still uniform and pink.
Type 12a on being segregated in the second growing of F 3 in the
season of 1913 yielded 100 plants of F 4 in 1914, uniform and of deep
red flower color. F 5 , of 10 plants in 1915, and. also F 6 , of 10 plants in
1916, produced uniform individuals of deep red flower color.
"We find, then, in types 12 and 12a definite fixations of the lorii-
folia type, one with uniformly pink flowers and one with uniformly
deep red flowers.
e. Aubiculata derivatives
Type 8 is represented in F 2 by a plant which had a leaf with an
extremely constricted base (cf. pi. 70) and deep red flowers. It is
not a typical auriculata derivative, but is included under this heading
because it resembles the members of this class more closely tha n those
of any other. F 3 , 12F 3 H 2 P 3 P 41 , consisted of 25 plan$& which were
uniform in height, habit, and flower color, and in agreement with F 2
in these respects. The leaves, however, we^'of two distinct types, 16
auriculata of type 8 and 7 sessilifoliI of type 16 (cf. pi. 78), the
latter being near to the type of macrophylla. No further generations
of this line were grown.
Type 10, as shown by the drawing (.pi. 72), had a peculiar leaf,
near to the macrophylla type, yet deeply constricted at the base into a
narrow and extremely abbreviated structure which may resemble a
petiole or only a deeply constricted blade. There were, however,
auricles partially clasping the stem and slightly decurrent. The leaf
form was that characteristic of N. Tabacum var. macrophylla purpurea
(cf. Setchell, loc. cit.). All 24 plants of F 3 had the same type of leaf
as F 2 , but the flowers were of three fairly readily distinguishable
shades ; 3 were red, 16 pink, and 5 light pink. F 2 had very dark pink
flowers. The line was not grown in further generations. -^S*
Type 6a is a true auriculata derivative which segregated in F 3
from an F 2 latipolia selection. Its occurrence and behavior are de-
scribed in connection with the account of type 6, tttf latipolia type
from which it segregated. Grown in the pure line for five generations
it has remained constant for the auriculata type of leaf.
480 University of California Publications in Botany [Vol. 5
/. Sessilifolia derivatives
Type 11 (cf. pi. 73) in F 2 gave 25 plants in 12F 3 H 4 P 41 P n , all
vigorous except one, but that one showed the. same characters of leaf
and flower as the others. All 25 plants possessed a sessilipolia type
of leaf very close to the F 2 parent and uniform among themselves.
There were two distinct shades of color of the flowers, 9 red and 16
pink. No further generations of this line were grown.
Type 14 (cf. pi. 76), so far as F, is concerned, was one of those
having sessile leaves of a broadly lanceolate type and pink flowers.
There were 25 plants in 12F :! H 2 P 3 P 3S , 24 had sessilipolia leaves of
type 14, while one (a "filler") had auriculata leaves like type 8; 19
had pink (or light pink) flowers, while 6 had red flowers. This line
was not followed through subsequent generations.
Type 15 (cf. pi. 77) was represented in F 3 , 12F 3 H 2 P :1 P 10 , by 25
vigorous plants which seemed surprisingly uniform and approached
macrophylla very closely as to leaf and color of the flower. In the
flower, however, the color seemed even darker than that of macrophylla,
there were only slight traces of the white triangular markings on the
limb, the limb Avas much more deeply lobed, and the tube less stout
and with the infundibulum much less abruptly swollen. These differ-
ences seem to indicate that type 15, which all the F 3 plants closely
resemble, is not an exact recombination representing macrophylla.
Type 15 was represented in 1913 by two families, F 3 of 10 plants
and F 4 of 100 plants. Both families were uniform as to individuals,
and agreed with the F 3 population grown in 1912 as well as with the
F 2 ancestor of the season of 1911. As this line seemed to be constant
and very close to, although not absolutely identical with, macrophylla,
differing in flower shape and leaf shape to some extent, type 15 was
considered to be a fixation and no further cultivation of it was made.
Type 16 (cf. pi. 78), which in F 2 approached macrophylla very
closerjin leaf, flower shape, and flower color, was represented in F 3 ,
12F s IiS|gjBL by 25 plants. These were all alike and closely resembled
the F 2 paren\in all respects except in leaf shape. Fifteen had sessili- .
folia leaves ontype 16 while 8 had auriculata leaves approaching
those of type Kl^efe-pl. 72). This line was not grown in further
generations.
Type 18 is the designation given to an F, plant, of which no draw-
ing was made. It seemed close to macrophylla, but the flower color
1922] . Setchell-Goodspeed-Clausen : Nicotiana Tabacum 481
was pink and the leaves were more slightly attenuate at the base.
F 3 , 12F 3 H 4 P 35 P 38 , gave 25 plants, 13 of which had the sessilipolia
leaf of type 18 ; 7, auriculata of type 10 ; and 5, auriculata of type 8.
In flower color. 17 were some shade of pink and 8 red. The line was
not grown in further generations.
Type 20 was not selected for illustration in F 2 , but was a plant
chosen because of its very close resemblance to macrophylla, coming
even closer than type 16. The F 3 , 12F.,H 4 P 40 P 44 , consisted of 25 vig-
orous plants of remarkable uniformity. In height, habit, inflorescence,
flower, color, shape, fruit, etc., the details follow those of macrophylla
so closely as to be indistinguishable unless possibly by careful and labor-
ious biometric study. This type may represent a practically pure
recombination equivalent to macrophylla, and is to be compared and
contrasted with type 15.
In 1913 two families of F 4 , one of 21 plants and the other of 100
plants, were uniform, as were 3 families of 50 plants each of F, in
1914. In 1914, however, a surprising thing happened. ^A fourth
family of F 5 , consisting of 50 plants, was uniform except one plant
which had pink (instead of red) flowers and an auriculata leaf ap-
proximating type 8 or 10. It seems certain that this plant must have
been an intrudeV, but its seed was saved under bag and grown and is
noted below and on the pedigree chart as type 20a. The other 3 plants
of F 5 whose seed was sown in 1915 gave type 20 in F c in families of
10, 9, and 8 respectively, and in turn the seed of 4 individuals of
"pure" type 20 gave, in 1916, uniformity in families of 10 each.
Type 20a, which originated or intruded in 1914, in one plant of
F 5 of type 20 gave in F„, in 1915, 10 plants segregating for flower
color and probably also for leaf characters, although the notes taken
are inconclusive on the latter point. In 1916 F 7 of 10 good plants
showed uniformly red flowers, but 7 had sessilifolia leaves, 4 of which
were decidedly contracted at the base and 3 had very short winged
petioles (auriculata of type 8 or type 10). On the whole it seems
most likely that the single plant in the F 5 family was an Intruder,
since all other families of the line have been constant sinee F 2 . A stray
seed somewhere along the processes of culture would explain it and
its appearance is all the more incomprehensible asra matter of inclu-
sion in the pedigree of type 20, as it is so close "to macrophylla as to
seem practically identical with it.
482 University of California Publications in Botany [Vol. 5
5. SUMMAKY OF FLOWER COLOR OBSERVATIONS IN F 2 AND
SUBSEQUENT GENERATIONS
Iii tables 3 and 4 we have summarized the numerical data with
respect to flower color inheritance in F 3 and in the subsequent popu-
lations. In table 3 are assembled data with respect to the behavior
of red flowering selections from populations segregating for red and
pink. It will be noted that all the five selections which were made
bred true for red flower color in the succeeding generations. In table
TABLE 3
INHERITANCE OF RED FLOWER COLOR IN Fa, el seq.
Type Numbers
Garden Numbers
Flower color of population
8
12F 3 H 2 P 3 P«
25 red
12a
14F 4 H 4 P 41 P 12 P,
100 red
15
12F 3 H 2 P 3 Pi 0
25 red
16
I2F3H2P3P8
24 red
20
12F 3 H 4 P 40 P 44
25 red
TABLE 4
POPULATIONS FROM PINK FLOWERING SELECTIONS OF ALL SHADES IN F 3 et seq.
Flower color classification
Type
Parent
Num-
Garden Numbers
Color
bers
red
pink
light pink
3
I2F3H2P3P14
light pink
14
6
12F 3 H 4 P 2 P 1S
pink
25
7
I2F3H2P13P.18
light pink
25
12
I3F4H4P41P12P8
pink
88
12
13F 4 H 4 P 41 P I2 P 9
pink
100
21
12FsH 4 P 4 P 2 9
light pink
25
1
12FsH 2 P7P49
light pink
5
19
(or light pink)
2
12F3ILP3P30
light pink
1
24
(13 light pink)
5
12F3H4P41P14
pink
8
16
(or light pink)
9
K
12F 2 H 4 P4,P 8
pink
4
21
(or light pink)
10
12F 3 H 4 P4iP 17
pink
3
21
(5 light pink)
11
^gF3H 4 P4lP 9
pink
9
16
(0 light pink)
12
12F 3 li 1P41P1J
pink
10
15
(0 light pink)
13
12F 3 i8^P 4 4
pink
4
21
(2 light pink)
14
12F 3 H 2 PXj)8
pink
6
19
17
12F 3 H,P 4 P|P i7
pink
3
22
18
12F3H 4 P 36 Pl> r> -
pink
8
17
19
12F 3 H 4 P 35 P 4 3
pink
25
(5 darker red)
Totals of segregating populations
60
187
(Types 2 and 19
excluded)
I 922 ] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 483
4 are assembled the data from ptnk flowering selections from popu-
lations which showed segregation into red and pink. In this table the
populations which bred true for pink are assembled in the upper
portion of the table, and those which showed further segregation into
red and pink are assembled in the lower portion. Of the 18 selections
made, 7 bred true for pink (or light pink), and 10 gave segregation
in the succeeding generation in about the ratio of 3 pink : 1 red. The
total figures for the 10 populations — 187 pink : 60 red — are in very
satisfactory agreement with the simple Mendelian ratio. The family
of type 19 behaved in an anomalous fashion, which may indicate mis-
classification of the F 2 parent ; and the family of type 2, which showed
only one red plant has been included among those which bred true for
pink. Strictly light pink selections should have given only light pink
flowers in subsequent generations ; the pink ones should all have given I
segregating populations. The evidence indicates that this result would
be obtained if segregation -occurred for only one pair of allelomorphs.
The difficulty, in part at least, appears to be the result of segregation
of modifying factors in the populations. These factors apparently
have an effect on flower color sufficient to obscure segregation into
pink and light pijik, but not enough to obscure the segregation into
red and pink. The actual results indicate an approximate agreement
with expectation, but the breeding test clearly is necessary in order
to determine the actual distribution of the pink individuals into their
genetic classes.
6. LATER SOWINGS OF F 2 AND F 3 OF THE ANGUSTIFOLIA-
MACEOPHYLLA SERIES
In 1916 and 1917 certain families of F 2 and P 3 of H 2 were grown
in order to reexamine them in the light of data previously collected
and to determine whether or not any more definite classifications could
be made than those stated in the preceding pages. The populations
grown are described briefly below.
16F 2 H 2 P 0 , as the population number would indicate, was a sowing
of seed of lOFjtpPg from the original F t population of EL. As in
previous cases, the segregation as regards leaf shape (was so complex
as to preclude definite classification. The types previously noted for
second generation populations were all in evilfllnce and along with
them practically every sort of intermediate. The height of plants
and general habit likewise agreed with the description previously
given.
484 University of California Publications in Botany [Vol.5
It was possible as in previous instances to segregate the plants into
definite flower color classes. In order to make this segregation as
accurate and free from bias as possible a special method of classifica-
tion was adopted. At the height of the blooming season, single typical
flowers were collected from each plant of a population and placed in
vials correspondingly numbered. These specimens were then taken
into the laboratory, where they could be classified under optimum light
conditions. The specimens so collected could then be shifted around
into their phenotypic classes and properly compared with each other
and with the parent colors. The color classification thus obtained
was individually recorded, and later the population was checked over
in the field to insure correction of any errors of classification. The
surprising feature of this population was a sharp, three-class segre-
gation into red, pink, and light pink; the reds the shade of macro-
phylla, the light pinks almost exactly that of angustifolia, and the
pinks intermediate between the two. Within the classes there ap-
peared to be no significant differences in depth of shade. Two plants
bore no flowers. The ratio obtained was 15 red : 23 pink : 10 light
pink.
16F„H„P 17 was likewise a sowing of the seed of one of the original
F x plants, in this instance of 10P 1 H 2 P 17 . As respects habit, height,
and leaf shape, there was a strict resemblance throughout of this
population to the one described above. Flower color was studied in
the same manner and with substantially the same results. However,
in this population there was a shading off from pink to light pink,
such that it was impossible to draw a sharp line between these two
classes as was done in the previous population. The shading off was
abrupt, but there were, nevertheless, a few plants on the border line.
The observed ratio was 16 red : 34 pink and light pink.
Hp 1917 six F 3 populations, each containing approximately 100
planra| were grown in order to make further studies of the inheritance
of leaiAhape. It was impossible, however, to study these plants as
thorougmpas might have been desired on account of conditons ob-
taining duriHtt 1917. However, specimens of leaves from each plant
were pressed preserved and these were studied and classified in
the summer of 19l\ A brief account of each population follows:
17F s H 2 P 17 P e w3%erssowing from 16F„H 2 P 17 P 6 , a stenophylla
selection. With respect tVj.eaf base characters the segregation was
phylla class approximating type 1 in appearance, and an auriculata
roughly but rather
STENO-
1922]
Setchcll-Goodspced-Clausen:
Nicotiana Tabacum
485
class approximating type 10. Within the stenophylla class there
was a variation in the amount of "wing" on the petiole and in the
type of blade base, some having the abrupt base of type 1, whereas
others had an attenuated type of blade which gradually drew in to
the petiole. In the auriculata class there was also a variation from
the strict form of type 10 to a type which lacked the flaring auricle
typical for that form, and had a very short naked petiole. In addition
to this variation in the amount of "wing" of the constricted class
there was also a difference in the presence or absence of attenuation
noted for the stenophylla class, some plants having leaves abruptly
drawn in to the midrib, whereas others were very markedly attenu-
ated. The difference in this respect appeared to be equivalent in the
two distinct classes, i.e., it was independent of any difference in the
' ' petioled " or " constricted ' ' condition. "With respect to stenophylla?
vs. auriculata the segregation was 66 stenophylla : 32 auriculata.
17F 3 H 2 P 17 P 8 was a sowing from 16P 2 H 2 P 17 P 8 , another steno-
phylla selection.^ The leaf classes obtained here were two,' steno-
phylla (type 1) and sessilifolia (type 15). The segregation into
the two classes was distinct, but, as in other populations, there was a
great deal of variability in each class. There was attenuation of the
kind previously noted in both classes. Some of the petioled individuals
had distinct wings, but the larger number were naked. Some few
individuals had very short petioles. The segregation ratio was 76
stenophylla : 24 sessilifolia.
17F 3 H 2 P 17 P 19 was a sowing from 16F 2 H 2 P 17 P 10 , a stenophylla
selection. The population was remarkably uniform in leaf shape,
which closely approximated angustifolia with minor differences. The
straplike leaves which are a characteristic feature of the upper por-
tions of plants of angustifolia were lacking in this population, and
the leaf tip and distal portion of the leaf blade did not narrow so
gradually in this population as in angustifolia. Otherwise, the char-
acters of the plants throughout were closely similar to angustifolia.
17F,H 2 P 17 P 22 was a sowing of seed of 16F 2 H 2 P 17 P 22 , a stenoph^la
selection. Of the six F 3 populations studied, this one exhibit^ the
greatest diversity in segregation. With respect to leaf base characters,
there were two outstanding classes, stenophylla and SESSidfOLiA (type
15), which could be separated readily. Within the stenophylla class,
however, most of the individuals exhibited a more cnfness winged con-
dition. Within the sessilifolia class, on the other hand, most of the
individuals exhibited more or less narrowing of the leaf base, like
486
University of California Publications in Botany [Vol.5
type 14. A few of the sessile individuals, instead of exhibiting gradual
and uniform narrowing toward the base of the leaf, were constricted
to a degree intermediate between auriculata of type 10 and sessili-
polia of type 15. With respect to stenophylla versus sessiltpolia
the observed segregation was 67 stenophylla : 32 sessilipolia.
17F 3 H 2 P 17 P 3 was a sowing of seed of 16F 2 H 2 P 17 P 3 , an F 2 sessili-
polia selection. The leaves throughout had the sessile type of leaf
base characteristic of macrophylla, but there were many modifications
of it in the population. A rough classification with respect to these
modifications of the macrophylla type of leaf base gave the following
results :
On 59 plants, the leaf bases were very nearly the form typical for
macrophylla.
On 22 plants, the leaf bases were gradually attenuated toward the
base, resembling lanceolata of type 13 as a mean. This at-
tenuated form of the sessile leaf was a very striking feature of
this population.
On 10 plants, the leaf bases were intermediate in type between
lanceolata of type 13 and the typical macroph ylla form.
On 2 plants, the base of the leaf immediately above the point of
attachment was noticeably constricted, the leaf base thus formed
being intermediate between the macrophylla type and auricu-
lata of type 10.
On 2 plants, the leaves were intermediate in constriction of the
leaf base between the strict macrophylla type and that of the
two plants described immediately above.
The classification here given is presented only to show that the
sessile type of leaf base characteristic of macrophylla is subject to a
number of very definite modifications which probably account for some
of the complex types of segregation observed in other populations.
17F 3 H,P 17 P 12 was a sowing from 16F 2 H 2 P 17 P 12 , a sessilipolia
selection. With respect to leaf base segregation there were two dis-
tinc»classes, sessilifolia (type 15) and auriculata (type 10). There
was hWl also a marked degree of variation within the classes. Within
the sessiT^plass the variation was in amount and kind of narrowing
of the leaf blade toward the base. A few plants showed a condition
approaching Ae auriculata type in this respect, whereas others
showed a graduatt^Jtenuated form of narrowing such as has been
noted before in other populations. Within the auriculata class most
of the individuals instead of possessing the slight wing and flaring
I 922 ] Setchell-Goodspeed-Clausen: Nicohana Tabacum 487
auricles of type 10 had short naked petioles. A few were strictly of
type 10. The following segregation ratio was noted : 61 sessilifolia :
27 AURICULATA.
7. CROSSES OF DERIVATIVES WITH THE PARENTS
In the preceding account we have pointed out that by growing
definite hybrid selections in the pure line through a number of gener-
ations it has been possible to establish a certain number of stable
derivatives which represent more or less obvious recombinations of
characters of the original parents. In a Mendelian sense, they repre-
sent stable reorganized germinal complexes containing hereditary ele-
ments that have been derived from both parents. Obviously such
recombinations of Mendelian units must differ in fewer units from
either parental type than did the parental types from each other. To
test some of these derivatives we have crossed them with the original
parents, usually with the one to which they bore the closest resem-
blance, in order to observe how complex a type of segregation the
hybrids thus obtained would exhibit as compared with that of the
original angustifolia-macrophylla hybrids. In so far as they have been
studied to date, a description of these hybrids and their progenies
follows :
SESSiLiFOLiAxmacrop7f ?/^«. P 5 sessilifolia of type 20 was crossed
with macrophylla giving H 50 = type 20J x macrophylla,^ and H 5t =
reciprocal thereof. The derivative parent here very closely resembles
macrophylla throughout in flower color and shape, habit, leaf shape,
etc. ISFiHjo and two families of 50 plants each, were equiv-
alent in every respect. The plants were very close indeed to macro-
phylla, as is also the sessilifolia parent. The only difference readily
observed was some variation in the amplitude of the corolla. In H-,,
a plant with a larger and one with a smaller corolla were selected for
pure seed. In F 2 , grown in 1916, one family of H 50 and two fakiilies
of H 51 , of 50 plants each were grown. The flower color in^the F 2
populations was throughout that of macrophylla and the le£f charac-
ters also were those of macrophylla. All three families jrere remark-
ably uniform, not only agreeing with one another butfiiniform as to
indivduals. They all resembled closely the macrophj/Ua type and there
was no definite segregation of any kind in themfi The three popula-
tions appeared to be replicas of macrophytta throughout except that
they were slightly more robust.
488 University of California Publications in Botany [Vol- 5
Latifolia x angustifolia. F 5 latipolia of type 6 was crossed with
angustifolia giving H 52 = type 6$ x angustifolia^ and H 53 , its recip-
rocal. The derivative parent possessed the short winged petiole char-
acteristic of latifolia of type 6. In ¥ 1 50 plants of each cross were
grown. They exhibited the long naked petiole characteristic of angus-
tifolia.
In F 2 two" populations of 50 plants each were grown. In color of
flowers the two populations were light pink throughout, closely cor-
responding in this respect to angustifolia. In leaf shape the segre-
gation was sharply into two classes: the stenophylla type of leaf
base (long, naked petiole) and the latifolia type (shorter, winged
petiole). There was some variation in the stenophylla class sug-
gesting intermediacy between angustifolia and latifolia, but the forms
exhibiting it showed a graded series from strict stenophylla to inter-
mediate. The latifolia class was very uniform and sharply set off
from the other class. The segregation ratios observed were as follows :
Stenophylla Latifolia
16F 2 H 62 Pi 6 42 8
16F 2 H 53 P 36 36 14
Totals 78 22
Auriculata x macrophylla. F 5 auriculata of type 6a was crossed
with macrophylla giving H 54 and H 58 — F 5 type 6a§ x macrophylla^
and H,- and H 39 , their reciprocals. It should be observed that type
6a is an early segregant from the latifolia of type 6 of H 5 „ and H 53 .
In F x 50 plants were grown of each of the four parents. All four
populations were equivalent in every respect. All the plants had pink
flowers, although one plant had flowers of a lighter shade than the
others, and leaves of a shape somewhat intermediate between the two
parents, i.e., they were more contacted at the base than macrophylla.
but much less so than those of type 6a. One planl of B 55 , namely
lSFjBwPm, showed larger corollas than any of the other F t plants
of any^femily, and was selected for further breeding.
In F||£our families were raised and they proved to be equivalent
in all respelte. except as noted. There was sharp segregation for leaf
shape into the|BjSSiLiFOLiA and the sharply constricted auriculata type.
In the SESSiLiFom class there were a number of obvious intermedi-
ates, as might be expected from the characters exhibited by F 1( but
they formed a continuouV-series with the strict sessilifolia forms.
The auriculata class did not intergrade with the dominant class.
1922 ] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 489
Segregation for flower color was studied by the method described above.
The color distinction between red and pink was sharp and easily drawn.
In the pinks, however, there was a continuous series of shades from
the deep" rose pink characteristic of F x to the light pink typical for
angustifolia. Numerical data are given in table 5.
TABLE 5
F 2 SEGREGATION OF PINK AURICULATA X RED SESSILIFOLIA.
Garden Numbers
Pink
sessilifolia
Red
sessilifolia
Pink
auriculata
Red
auriculata
16F 2 H 54 P 7
32
6
9
3
16F 2 H 55 Pi6
23
11
11
5
16F 2 H i5 P 29
26
13
7
4
16F 2 H 5S P 26
26
11
7
2
16F 2 H Ma P 35
26
12
6 -
2
Totals
133
53
40
16
Expected
136
45
45
15
In 1918 in connection with flower size studies three more popula-
tions of F„II 35 were grown. Leaves were collected from each plant
and pressed, and leaf shape studies were made on these preserved
specimens. The studies were not so satisfactory as those made in the
field, where it is possible to examine all the leaves on a given plant ;
nevertheless, the data derived from the studies agreed substantially
with those obtained in 1916 from field studies. It was noted in these
studies that there was a distinct class of "attenuated" leaves similar
to those which have been described in previous populations. Both
attenuation and constriction were observed to occur in the leaves of
some individuals, and this gave rise to some difficulty in classification.
Numerical data are given in table 6.
TABLE 6
F 2 SEGREGATION OF SESSILIFOLIA X AURICULATA.
Garden Numbers
Sessilifolia
AuRIC^nj.TA
18F 2 H65P40
67
18F 2 H 55 P 41
79
J* 18
18F 2 H 55 P<6
79
17
Totals
225
63
490 University of California Publications in Botany [Vol. 5
Stenophylla x an gusti folia. Reciprocal crosses were made between
F 5 , stenophylla of type 21 and angustifolia; H, 0 = F 5 type 21$ x
angustifolia,^ and H g7 , its reciprocal. Stenophylla of type 21 has been
described previously as a stable derivative closely approximating
angustifolia in all its characters. F 1 families of 50 plants of each
hybrid were raised in 1915. They were uniform throughout and so
close to angustifolia in all characters as to be indistinguishable from
it. One plant seemed to be of a slightly darker pink corolla color.
lSFoHggaPn was the only F, family raised. The flower color of this
population was about the shade of angustifolia and uniform through-
out the population. The family showed only a slight variation in the
base of the blade such as is also seen in populations of angustifolia.
S. DISCUSSION OF EESULTS OF THE ANGUSTIFOLIA-MACEOPHYLLA
SEEIES OF INVESTIGATIONS
Obviously the outstanding result of this series of investigations of
hybrids between angustifolia and mucrophylla is a demonstration of
the complexity of the germinal differences which exist between the
two varieties with respect to practically every character contrast which
may be made between them. Only in one instance, the contrast be-
tween the light pink flower color of angustifolia and the red of macro-
pkylla, is a simple Mendelian formulation possible. Here evidently
the main flower color difference is dependent upon a simple allelo-
morphic contrast. Red x light pink gives ¥ 1 intermediate pink, and F 2
1 red : 2 intermediate pink : 1 light pink. The red segregants breed
true for red, the light pinks for light pink, and pink continues to
segregate in the typical mono-hybrid fashion. Inasmuch as the inter-
mediate pinks and light pinks form an intergrading series, it is con-
venient to look upon red as the recessive color. Accordingly we give
this pair of factors the designation, Rr, following the mnemonic system
advocated by Morgan, and shall so refer to it in what follows. The
difficulty among the pinks appears to be due not only to phenotypic
variant but also to the existence of modifying factors which have a
relativeryyjlight effect upon flower color expression. These less strik-
ing modifica^ons of flower color we are seeking to analyze further.
In the leafilshape investigations, the complexity of the results is
plainly evident from an examination of the data presented in the fore-
going pages. Although the behavior here is complex, in every feature
it parallels the Mendelian expectation for complex factor relations.
<
1922 J Setchell-Goodspeed-Clausen: Nicotiana Tabacum 491
In F 2 the variety of leaf shapes encountered was nothing short of
bewildering and series could be built up from them showing complete
intergradation from one type to another. Selection of phenotypes
from F 2 , however, gave P 3 populations in which the complexity of
segregation was usually reduced in a very definite fashion. Most of
the populations exhibited fewer classes than F,, and the selection of
F 2 phenotypes held the expression of F 3 within very definite limits.
Thus selection of sessilifolia forms gave in F 3 either all sessilifolia
or approximately 3 sessilifolia : 1 auriculata. In no case did such
selections give F 3 populations with stenophylla or latifolia leaf
types. A summary in detail of the type of populations produced is
as follows.
Stenophylla selections may segregate in a variety of ways. Thus,
type 1 showed approximate segregation into 3 stenophylla : 1 sessi-
lifolia. Type 21 bred true to the stenophylla characters. Among
stenophylla selections grown in 1917, population 17F 3 H 2 P 17 P 6 ,
showed approximate segregation into 3 stenophylla : 1 aurtculata;
17F 3 H 2 P 17 P 8 , 3 stenophylla :1 sessilifolia; 17F 3 H 2 P 17 P 9 bred true
for stenophylla, and 17F 3 H 2 P 17 P 22 gave a rather indefinite segrega-
tion of approximately 3 stenophylla : 1 sessilifolia. Latifolia
derivatives crossed with angustifolia gave ¥ 1 stenophylla and F 2
approximately 3 stenophylla : 1 latifolia.
Latifolia selections also segregate in perplexing fashion. The F x
population of angustifolia x macrophylla is typically latifolia in its
characters. Latifolia under certain conditions therefore is a very
complex hybrid expression. Recurrence of complex segregation of a
latifolia selection is shown in F, of type 2. F a of type 3 exhibited
a rather anomalous segregation ratio of petioled and sessile forms.
Type 5 apparently bred true, although there was one anomalous plant
in the population. Type 6 exhibited complex segregation, with an
indication of a ratio of 3 latifolia :1 auriculata; with subsequent
establishment of both latifolia and auriculata in constant races.
Type 7 bred true for a type of leaf like F x ; and type 9 gave approxi-
mate segregation of 3 latifolia : 1 sessilifolia. J±
Loriifolia and lanceolata derivatives are really variations of the
sessilifolia type. They were both produced in constant^aces. Their
genetic relation to the other forms is, however, nojpwell established
by this series of investigations. Although these Jswo are really quan-
titative variations from the strict sessilifolia type, nevertheless, cer-
tain of our data indicate discontinuous inheritance of these contrasts.
■±92 University of California Publications in Botany (Vol. 5
The same quantitative factors that differentiate the narrow-leaved forms
of sessilipolia from the typical broad-leaved forms may apparently
differentiate narrow-leaved stenophylla, latifolia, and auriculata
forms from the more typical broad-leaved ones. It is of interest in
this connection to note that loriifolia derivatives have much narrower
leaves than either of the original parents.
We have been especially interested in these loriipolia derivatives
because they are somewhat like the narrow-leaved forms that Hassel-
bring (1912) found among Cuban tobaccos, and which are so well
recognized among Cuban growers as to have received the specific desig-
nation of lengua de vaca or "cow's tongue." Our results indicate
that it is possible for such forms to arise by segregation from crosses
between broader leaved forms. The lengua de vaca of the Cuban
growers is, therefore, probably a segregation product which could
easily be eliminated by the adoption of proper pure line methods of
breeding.
Auriculata forms appear to breed true whenever segregated. The
exception is type 8, which requires further investigation. It may be
a leaf type similar to auriculata but of different genetic constitution.
Auriculata of type 10 bred true in F 3 . The auriculata form 6a,
which segregated from type 6 bred true thereafter. Auriculata
crossed with macrophylla, H 54 , H 55 , H 58 , and H- 0 , gave sessilipolia in
Fj and in F 2 3 sessilifolia : 1 auriculata.
Sessilipolia forms have broad sessile leaves, the distinguishing
feature being merely their sessile mode of attachment. Of such selec-
tions from the original F 2 populations, four, with the exception of one
anomalous plant, bred true for sessilipolia. Each of the other three
populations segregated into sessilipolia and auriculata in about the
ratio of 3 sessilipolia : 1 auriculata. Two sessilipolia selections
were grown in 1917. One of these bred true to sessilifolia ; the other
gafce 3 sessilifolia : 1 auriculata. The behavior of sessilifolia in
relation to stenophylla and latifolia is explained above.
On the basis of these results we may distinguish certain definite
allelonwphic pairs of factors as follows
Ss, sfjgropiiYLLA versus sessilifolia : SS being long petioled like
angustifom^&nd ss broadly sessile like macrophylla. The heterozygote
may possibly ap«roach an intermediate condition similar to latifolia.
LI, STENOPHYnL* versus latifolia : LL being long petioled like
angustifolia, and 11 short petioled like latifolia and with a distinct
but not broad wing. Tne contrast is really one of SSLL, stenophylla
i 922 ] Setchell-Ooodspeed-Clausen: Nicotiana Tdbacum 493
versus SS11, latifolia. Both ssLL and ssll are probably typical sessi-
lifolia forms. Here again the heterozygote probably shows an indis-
tinct type of intermediacy.
Aa, sessilifolia versus auriculata : AA having the broad clasp-
ing leaf base characteristic of macrophylla, and aa the deeply con-
stricted leaf bases with flaring auricles characteristic of auriculata.
The contrast here is really one of ssAA, sessilifolia versus ssaa, auri-
culata, for these factors are evidently latent when in combination with
SS or Ss.
Fig. 2. Leaf base types of the angustifolia-macrophylla series. Left to right:
STENOPHYLLA, LATIFOLIA, SESSILIFOLIA, and AURICULATA.
Some of the possible genotypes, their phenotypic expression, and
genetic behavior are included in table 7. Here only monohybrid segre-
gation is considered because it is doubtful, on account of the various
types of intermediacy shown by heterozygotes, whether it would be
possible to classify dihybrid and trihybrid populations satisfactorily.
TABLE 7
genetic behavior of various leaf type genotypes.
Genotype
Phenotype
Genetic behavior
SSLL A A
STENOPHYLLA
Breeds true
SsLLAA
STENOPHYLLA
3 STENOPHYLLA
1 SESSILIFOLIA
SSL1AA
STENOPHYLLA
3 STENOPHYLLA
1 LATIFOLIA
SSLLAa
STENOPHYLLA
Breeds true
SsLLaa
STENOPHYLLA
3 STENOPHYLLA
1 AURICULATA
SS1IAA
LATIFOLIA
Breeds true
SsllAA
LATIFOLIA
3 LATIFOLIA
LlfesSILIFOLIA
Ssllaa
LATIFOLIA
3 LATIFOLIA ^
fl AURICULATA
ssLLAA
SESSILIFOLIA
Breeds true r*
ssllAA
SESSILIFOLIA
Breeds true
ssllAa
SESSILIFOLIA
3 SESSILIFOLIA
1 AURICULATA
ssllaa
AURICULATA
Breeds true
494 University of California Publications in Botany [Vol..")
Although intermediacy of the heterozygote appears to be the normal
thing in these leaf shape contrasts, it is proper to state that this inter-
mediacy may depend to some extent upon the effect of modifying
factors rather than upon the heterozygous conditon of a pair of allelo-
morphs. Thus the intermediate conditon between stenophylla and
auriculata is met with in populations which do not contain auricu-
lata segregation products. There are so many modifying factors in
this series of investigations that it is probably impossible for us to
declare definitely that in any one instance our observed segregation
was wholly the result of segregation of one pair of allelomorphs.
Further investigations are in progress, the purpose of which is to
isolate and evaluate, if possible, certain of these subsidiary factors.
For the present we can only state our certain knowledge of their
existence, and our belief as to their various effects.
IV. CALYCINA-VIRGINICA SERIES
The calycina-virgimca series of hybrids and derivatives has received
much less attention than has been given to the previous series ; partly
because the differences between the parents are less striking and the
diversity of segregation products was not so great. Two hybridizations
were made : H 18 which had calycina for the female and virginica for
the male parent and H 20 which was the reciprocal cross.
1. PAEENTS OP THE CALYCINA-VIRGINICA SERIES
Elsewhere Setchell has given descriptions of calycina and virginica
("Maryland"). Like angustifolia and maerophylla, these two varie-
ties possess distinct sets of characters which set them apart from the
other Tabacum varieties that have been grown in the University of
California Botanical Garden.
Calycina is represented in our cultures by a variety, U. C. B. G.
110/05, which was originally received from the Botanical Gardens of
CamT|ridge University. The figure previously published (cf. Setchell.
loc. cWj^xA. 4) well represents the general habit and type of the plant.
The para&ular features of the characteristic teratological flower of
calycina arajbetter shown in plate 79, in which the leaf shape is also
illustrated inTtpre characteristic fashion. For illustrations of some
of the variationsrWuch occur in the expression of the split hose-in-hose
flowers the reader is iWerred to Goodspeed and Clausen, 1917, plate 45.
The legends to the twoHgures of this plate should be reversed as indi-
cated in the references to the plate in the text of this earlier article.
1922] Setchell-Goodspeed-Clausen: Nicotiana Tabacum
495
In stature, as previously mentioned, calycina belongs to the low
corymbose group of Tabacum forms. In height the central axis usually
varies between 60 and 75 cm. The laterals, however, which develop
later from the base, overtop the central axis and reach a height of
120 to 135 cm. Like macrophylla, central axis and laterals bear close
panicles of corymbose racemes, the laterals developing successively
from the base. The stems and branches are stouter than those of
angustifolia and the leaves do not droop so considerably. In these
respects calycina occupies an intermediate position between angusti-
folia and macrophylla.
The leaves of calycina, as plate 79 will show, are sessile, but they
are distinctly different from those of either angustifolia or macro-
phylla. Curiously enough, however, they do rather closely approxi-
mate certain of the derivatives of the angustij ' olia-macrophylla series,
as, for example, the lanceolata and loriifolia leaves of types 13 and
14 respectively, illustrated in plates 75 and 76. The leaves vary from
broadly to narrowly lanceolate, tapering toward both base and apex,
and usually with a long curved tip. The broader leaves are borne at
the base of the plant, those above them becoming successively narrower
in a continuous series until the linear leaves or straplike bracts of the
inflorescence are reached. There are no auricles at the base of the leaf.
The inflorescence is in the form of a very close panicle of racemes,
the secondary axes of which are mostly patent, and more or less re-
curved or bent back. The flower as a whole is of a very characteristic
split hose-in-hose type. The corolla is usually split on one side, some-
times twice split, and more or less curved. The characteristic split-
ting of the corolla is seen even in very young buds and often the pistil
protrudes from them. Typically the calyx has an elongated whitish
green tube, with 3 to 5 of its tips more or less petaloid. Sometimes
strips of petaloid tissue extend down the entire length of the calyx.
The pod is ovoid oblong in shape. As it enlarges it splits the calyx,
which then withers and drops off like the corolla, leaving a naked,
whitish green capsule. The flower color is red fading to bluish purple,
apparently the same as that of macrophylla.
Virginica is represented by U. C. B. G. 78/05, a strah£received
from the United States Department of Agriculture unde/rae identi-
fication number "205-20-7." It is figured by Setchar^ plate 3, and
by Goodspeed and Clausen, plate 41, figure 1. Thaftypical leaf and
flower characters are well represented in plate SQJfeTewith.
In stature virginica belongs to the modeKatfe pyramidal group of
Tabacum varieties. It is conspicuously taller than calycina, the cen-
496 University of California Publicat ions in Botany |; Vol. 5
tral axis reaching a height of 150 to 175 cm. While strong laterals
develop they do not originate at the base of the plant as in calycina,
and they do not overtop the central axis. These characteristics to-
gether with the broad spreading basal leaves give the plant its pyra-
midal or conical shape. The leaves are very close in general shape to
those of calycina, but they taper less abruptly to either end. The apex
is prolonged into a fairly long point curved to one side, and the base
is expanded into two broad, partially clasping auricles.
The inflorescence consists of a more ample panicle than that of
calycina. The flowers are light pink in color, identical in this respect
with those of angustifolia. The tube and infundibulum are narrow,
gradually increasing in diameter from below in a funnel-shaped
fashion. The corolla lobes are broad at the base, but have long,
slender incurved points. Capsule and calyx present no very charac-
teristic features, although the calyx is persistent in contrast to the
deciduous calyx of calycina.
It will be seen from the foregoing descriptions that there are a
number of distinct character contrasts between calycina and virginica,
a brief note of which may well be made at this point. In flower color,
red of calycina is contrasted with light pink of virginica, the same
contrast which existed in the angustifolia-macrophylla series. Simi-
larly the split hose-in-hose flower of calycina is contrasted with the
normal one of virginica; low stature with tall ; and a less decided
contrast in leaf shape exists, depending upon the presence or absence
of auricles at the base of the leaf.
2. F 1 OF THE CALYCINA-VIRGINICA SERIES
In the season of 1910, 55 plants of lOP^^ and 58 of lOF^,, were
grown. In the season of 1911, 10 plants were grown of each of
kFJI 18 and llF^.
Like other hybrids which have been grown, these populations were
uniform and equivalent throughout. It was thought that IOFjH.,,,
showed a more distinctly pronounced trace of calycina characters than
did lOFJI^, but the populations of the same seed grown in 1911
showed njLappreciable difference in this respect.
In generliappearance the F x plants resembled virginica more than
they did calycha. The plants were somewhat shorter than virginica,
running up to 135 cm. In these plants it was noted that some of the
laterals overtopped the central axis as they do in calycina. The in-
florescence was in general of the ample type characteristic of calycina.
1922]
Setchell-Goodspeed-Clausen : Nicotiana Tabacum
497
The flower color was a deep pink intermediate between the two
parents. The flower shape was normal throughout save that on every
plant there was a small percentage of calyces with one or more pink
and somewhat broadened calyx tips, or with a streak of white on one
side. Sometimes these partially petaloid calyces were partly decid-
uous. In shape of flower the hybrid closely resembled virginica except
that the corolla lobes were longer and more decidedly mucronate.
Calyx and capsule were almost identical with those of virginica, the
calyx being typically persistent and accrescent. The leaves were some-
what broader proportionately than those of virginica, but they pos-
sessed the pronounced auricles of that parent. The usual gradation
in leaf shape on each plant from the broad basal leaves to the linear
bracts of the inflorescence was in evidence.
The main features of H 18 and H 20 are well illustrated in the draw-
ings of 10F 1 H 18 P 5 shown in plate 81. The general habit and charac-
ters are illustrated in the photograph of 10F 1 H 18 P 54 which is repro-
duced in plate 83, figure 1.
3. F 2 OF THE CALYCINA T VIRGINTCA SERIES
In the season of 1911 four F 2 families of the calycina-virginica
series were grown, viz., 11F 2 H 18 P 2;; , 11F 2 H 18 P 4!1 , 11F 2 H 20 P 7 , and
11F 2 H 20 P 26 .
As in the angusUfoUa-macrophylla series, the segregation exhibited
in those four families, comprising 97 plants, was nothing short of be-
wildering, and in most cases an intergrading series of forms connected
one character expression with another. However, an attempt was
made to classify the plants into categories suggested by the four pairs
of character contrasts existing between the parents. The results of
this classification are given in table 8.
TABLE 8
NUMERICAL DATA FROM F 2 POPULATIONS OF THE CALYCINA-VIRGINICA SERIES.
Corolla color
Corolla shape
Stature
Leaf width
pink
in-hose
alhose-
se
S
a
'f
Garden Numbers
-a
M
a
*j
J3
V
■a o
s
h
0
•3
V
-A «
o
o
u
H
'a
.SP
o
■a
O
a
J3
00
a
"3 />
1 f->
x>
13
a
11F 2 H 18 P 25
6
11
6
6
8
9
17
2J
* 5
17
7
11F 2 H I8 P 49
7
14
4
12
4
9
19
3
14
11
11F 2 H 20 P ?
5
9
11
7
8
10
U f
*6
8
21
4
HF 2 H 2 oP 2 6
5
10
8
10
6
7
12
5
6
15
8
Totals
23
44
29
35
26
35
59
16
22
67
30
498 University of California Publications in Botany t VoL - 5
In this cross, corolla color behaved in exactly the same manner as
it did in the angustifolia-macrophylla series. The same remarks as
to sharpness of segregation apply here as in that series. Red was
nearly always readily distinguishable, but pink and light pink formed
a more or less completely intergrading series. Taking the results in
this way, we obtain 23 red ; 73 pink and light pink, which is substan-
tially in accord with Mendelian expectations.
TABLE 9
F 2 SEGREGATION IN CALYCIN A-VIRGINICA SERIES.
Pink
Pink
Red
Red •
Garden numbers
normal
hose-in-hose
normal
hose-in-hose
16F 2 H 18 P 25
24
14
8
3
16F 2 Hi 8 P 49
25
8
14
3
I6F2H20P7
29
6
10
4
16F 2 H 20 P 38
30
8
11
1
Totals
108
36
43
11
Expected
112
37
37
12
With respect to corolla form some difficulty was encountered be-
cause the expression of the hose-in-hose character in the segregants
did not seem to be so extreme as it was in the parent, and a large
number of the plants showed slight traces of it, but sometimes in a
more pronounced form than in the Y x hybrids. Accordingly the classi-
fication of corolla form in table 8 is not a wholly satisfactory one.
The classification for stature and leaf width is subject to similar
remarks as to its definiteness. Here there was also a more or less
completely intergrading series of forms and no accurate measurements
were taken. However, there is no doubt that there was segregation
with respect to these characters, and a range of forms was obtained
\thich completely bridged the gap between the parents. The behavior
oflhese characters is to be considered in the light of their segregation
in subsequent generations.
In 1916 four additional V, populations of the calycina-virginica
series w&rf. grown in order to reexamine populations for the segrega-
tion of norifcal versus hose-in-hose flowers, and red versus pink flower
color. The method of classifying the flowers was that used in studies
of 1916 populauo^previously mentioned. The results of these studies
are given in table 9.V.
1922] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 499
In the segregation the same grading as before of the pinks into
two intergrading classes in the proportion of approximately 2 inter-
mediate pink : 1 light pink was observed, but it was even more difficult
to draw a line between light pink and intermediate pink because of
the effect of the hose-in-hose conditon on flower color expression in
those plants which bore teratological flowers. In the matter of segre-
gation into normal and hose-in-hose flowers, some difficulty was ex-
perienced because some otherwise normal flowering plants bore some
flowers which showed a tendency for the calyx to become petaloid,
and others bore flowers which showed a very slight hose-in-hose ten-
dency. A correspondingly slight hose-in-hose tendency is also present
in ~F 1 plants. These plants were classified as normal. Here again it
can be seen that the segregation ratios of 144 pink : 54 red and 151
normal : 47 hose-in-hose are in substantial agreement with Mendelian
expectation for contrasts in a single pair of allelomorphs in each case.
Moreover, the dihybrid ratio is substantially in agreement with that
expected for independent segregation of the members of these two pairs
of allelomorphs.
4. F 3 AND SUBSEQUENT GENERATIONS OF THE CALYCINA-VIRGINICA
SERIES
In 1912 twelve F 3 families of H 18 and five of H 20 were grown. They
will be grouped for consideration according to the characters which
TABLE 10
F 3 BEHAVIOR OF RED SEGREGANTS.
Garden numbers
Red
12F 3 Hi S P25Pn
25
I2F3H18P25P19
25
I2F3H18P49P12
25
I2F3H18P49P24
25
I2F3H20P26P25
25
/
the F 2 parent exhibited. In table 10 the data with respect toithe be-
havior of F 3 populations from red flowering F 2 plants ar&fjbllected.
Five such populations gave nothing but red flowering planm indicating
clearly that red segregants breed true. In table 11 thefflata from pink
flowering plants are similarly collected. The reader will not fail to
notice that some pink flowering selections were not heterozygous for
500 University of California Publications in Botany [Vol. 5
red. This bears out our statements as to the difficulty of classifying
pink and light pink. In the seven populations which produced red
flowering plants 38 plants had red flowers and 134 pink or pinkish
flowers ; again in substantial agreement with the behavior of flower
color in the angustifolia-macrophylla series. The behavior of segre-
gants classified as light pink is shown in table 12. Of the four popu-
lations from which data were gathered only one bred true to light
TABLE 11
F 3 behavior of pink segregants.
Garden numbers
Red
Pink
Light pink
12F 3 H IS P 25 P 7
5
16
4
12F 3 H 18 P 25 P 21
21
4
12F 3 H I8 P 25 P 2 5
6
19
12F 3 H 18 P 49 P 9
4
20
I2F3H18P49P10
11
13
I2F1H18P49P25
4
16
5 •
12F.,H 20 P 2 6P6
4
20
12F 3 H 20 P 2 6Pll
4
21
Totals for segregat-
ing populations
38
134
TABLE 12
F.i BEHAVIOR OF LIGHT PINK SEGREGANTS.
Garden numbers
Red
Pink
Light pink
12F 3 H 18 P, 5 P 24
23
12F 3 H 18 P 49 P 22
8
12
5
12F 3 H 2 ,P 7 P 9
6
15
4
12F 3 H 20 P 26 P 6
25
pink, one of the others bred true for pink, possibly a slightly darker
shade than true light pink, and two segregated for all three colors:
they must therefore have been pink heterozygotes.
In P 4 two populations each of H 1S and of H 20 were grown. Popu-
lation^HSF^^P^PjjPg from an F., population breeding true for red
gave i»14 100 plants all red flowering. Population lSF^^Po-P^P^
from the^pune F 3 population gave 97 plants all red flowering like
calycina. Population 13F 4 H 20 P 26 P B P 8 , which bred true for pink in
F ., gave in F 4 96 plants, all pink flowering. These three populations
were grown to F 7 without showing further evident segregation. The
1922]
Setchell-Goodspeed-Clausen: Nicotiana Tabacum
501
pink of the pink flowering derivative was at first considered somewhat
darker in shade than the light pink of virginica, but this line also
showed the hose-in-hose flower character, which sometimes makes it
difficult to determine flower color accurately. In later generations of
this line its color was noted as equivalent to the light pink of virginica.
TABLE 13
F 3 BEHAVIOR OF HOSE-IN-HOSE SEGREGANTS.
Garden numbers
Hose-in-hose
I2F3H18P25P21
25
*12F 3 H I8 P 25 P 24
23
I2F3H18P49P9
24
*12F 3 H 18 P 49 P 12
25
12F 3 H I8 P 49 P 24
25
I2F3H20P26P6
24
I2F3H20P26P11
25
* Apparently not so extreme as calycina.
TABLE 14
F 3 BEHAVIOR OF NORMAL SEGREGANTS.
Garden numbers
Hose-in-hose
Partial
Normal
12F 3 Hl 8 P25P7
9
16
12F 3 HlsP25Pll
4
4
17
12F 3 H 18 P 26 Pi 9
5
20
12F 3 H 18 P 25 P25
3
22
*12F 3 H 18 P 49 P 10
4
20
12F 3 Hi 8 P 49 P 22
25
12F 3 H I8 P 49 P 25
4
21
12F 3 H2 0 P7P 9
5
20
12F 3 H 2 oP 2 6P 6
7
3
15
12F 3 H2oP26P25
10
15
Totals
47
153
Taking up corolla form next, we may deal with the different popu-
lations in the same manner as was done in the case of flower color.
F 3 populations from F 2 hose-in-hose segregants are recorded in table
13. Seven populations were grown, all of which bred true tj> the
hose-in-hose character, although curiously enough two populations.
12F.,H ls P 2r ,P 24 and 12F 3 H 18 P 49 P 12 did not appear to exhibit so ex-
treme character expressions as calycina.
Only one partially hose-in-hose plant was grown in'F 3 . For the
sake of economy of space it is included in table 14, where it is marked
502 University of California Publications in Botany [Vol. 5
with an asterisk. Strangely enough, it was one of the two in the table
which did not throw hose-in-hose flowers. The other normal selections
all threw hose-in-hose flowering plants in the proportion of about 3
normal to 1 hose-in-hose.
In subsequent generations only the three families which were pre-
viously considered under flower color were grown. Normal flower
selections from 12F 3 H 18 P 25 P 11 gave two populations, one of 100 and one
of 97 plants. The plants all bore normal flowers. In 13F 4 H 18 P 25 P 11 P 13
it was noted that some flowers were split, but there was not even a
suggestion of approach to the true hose-in-hose condition. The other
population 13F 4 H 20 P 26 P 5 P 8 was from a hose-in-hose selection in the
TABLE 15
Fs BEHAVIOR OF TALL SEGREGANTS.
Garden numbers
Tall
Short
12F 3 H 18 P 25 P 7
19
6
12F 3 H 18 P 25 P 24
1
24
I2F3H20P7P9
6
19
TABLE 16
F 3 BEHAVIOR OF MEDIUM SEGREGANTS.
Garden numbers
Tall
Short
12F 3 H 18 P 49 P 12
23
I2F3H18P49P22
1
24
corresponding F 3 population. Ninety-four plants were grown to ma-
turity, all of which were strictly hose-in-hose. In subsequent gener-
ations these three populations bred true to type save for the sporadic
appearance of hose-in-hose flowers on plants which otherwise bore
nothing but normal flowers. This, however, is not an unusual phe-
nomenon even in pure line cultures of normal flowering varieties of
Tabacum, and it is extremely doubtful whether the hybrid derivation
ofVhese plants had anything to do with the production of occasional
split flowers.
As respects height of plants the F 3 data are given in tables 15, 16,
and 17,lfc|ich give the behavior of tall, medium, and short F 2 segre-
gants respectively. The behavior here is not very convincing. Prob-
ably the difficulty in judging the character and the influence of
variation in soil condition had something to do with it.
I 022 ] Setchell-Goodspeed-Clausen : Nicotiana Tabacum 503
In the subsequent generations the behavior was, however, more
definite. 13F 4 H 18 P 2;i P 11 P 9 was grown from a tall F 3 plant. No defi-
nite notes were taken as to height, but the population was noted as
varying. In F 5 and subsequent generations the line bred true to tall.
13F 4 H 1S P 25 P 11 P 13 was grown from a short F 3 plant. The ninety-seven
plants were all of low stature and in subsequent generations the line
bred true for low stature. 13F 4 H 20 P 26 P 5 P 8 was grown from a tall
F 3 plant. Ninety-four plants, although variable in height, all be-
longed in the tall class and in subsequent generations the line bred
true for tall stature. Nothing but a careful biometrical study under
TABLE 17
Fs BEHAVIOR OF SHORT SEGREGANTS.
Garden numbers
Tall
Short
I2F3H18P25P11
10
15
I2F3H18P25P19
16
9
12F,Hi 8 P„Ph
25
12F3H18P25P25
5
20
12F3H18P49P9
24
12F3H1SP49PIO
24
12F3H18P49P24
7
18
12F3HI8P49P25
9
16
12F3H20P2GP5
8
16
12F3H20P26P6
5
19
12F 3 H 2 oP26Pll
25
Totals
68
129
well controlled cultural conditions, however, would yield results capa-
ble of strict Mendelian analysis. However, it can be said that none
of the results here recorded preclude the possibility of such an analysis,
although it evidently can not be done in any simple qualitative manner.
As respects leaf width it was found impossible to make even such
a rough classification as was attempted in the case of stature. Here
again nothing short of a strict biometrical analysis would furnish the
basis for a Mendelian formulation.
As has been indicated above, three separate lines of thisjSeries
were carried out to the seventh hybrid generation. Of these^/me was
a recombination of characters from both parents exhibiting the tall
stature and normal flower of virginica with the red flojrer color of
calycina. One exhibited a stature intermediate between that of caly-
cina and virginica in combination with the normal flower shape of
504 ' University of California Publications in Botany [Vol. 5
virginica and the red flower color of calycina. The third had the tall
stature of virginica and red flower color, in association with the hose-
in-hose flower form of calycina. These three lines apparently bred
true for all their characters.
5. DISCUSSION OP RESULTS OF THE CALYCTNA-VIKGINICA SERIES
No extended discussion of results is indicated in connection with
the calycina-virginica series of hybrids because particular attention
was given to so few characters. Just as in the case of angustifolia-
macrophylla, so in this series of hybrids the character differences
proved to depend upon complex genotypic differences. Apparently
the flower color contrast in these two varieties was the same as that in
the angustifolia-macrophylla series, and the same relations with respect
to dominance and segregation were found to hold for it. Without
doubt we are dealing here with the Rr pair of allelomorphs as in the
previous instance. The demonstration of the simple factor relations
in the inheritance of the split hose-in-hose form of flower adds to our
series another pair of allelomorphs which we may call Cc (calycine).
In this case the dominance of normal over split hose-in-hose appears
to be nearly, if not quite, complete. The sporadic appearance of split
hose-in-hose flowers on otherwise normal plants does not even seem to
be clearly associated with the heterozygous genotype, Cc. The data
for height are not of sufficient accuracy or extent to warrant an at-
tempt at Mendelian formulation. It was again found possible very
easily to shuffle and recombine the characters occurring in the parent
varieties and to establish recombination derivatives in pure lines.
V. ALBA-MACROPHYLLA SERIES
1. PARENTS OF THE ALBA-MACROPHYLLA SERIES
Alba, which is one of the parents of the alba-macrophylla series,
is the "White" tobacco, U. C. B. G. 30/06, described by Setchell. It
is one of the taller forms of Tabacum, ranging in height from 165 to
220 c^k Typically alba is unbranched below ; above, it has flowering
branchesVorymbosely arranged in succession from above downward.
The leavesl^-e sessile, more ample, more rugose, and more velvety than
those of macro phylla. They are narrowed suddenly above the ex-
panded, somewhat auricled and partially clasping base. The leaves
1922] Setchell-Goodspeed-Clausen: Nicoiiana Tabacum
505
resemble those of macrophylla in shape but differ from them particu-
larly in the basal portion. The corollas are white with a yellowish
tinge ; but in shape, size, and general proportions they are very similar
to those of macrophylla. Line drawings of typical features of alba
are reproduced in plate 82. The reproductions of photographs of the
leaf of alba and of the F 4 hybrid of the alba-macrophylla series are.
shown in plate 84.
Macrophylla, U. C. B. G. 22/07, has been described above.
In these two varieties there are definite character contrasts in color
of flowers, macrophylla being red and alba white ; and in stature,
macrophylla being low of stature and alba distinctly taller. Other
contrasts also exist, although they are not so definite, in the style of
branching and in the shape and texture of the leaves. Like those
which have been considered above, this is a hybrid series in which
the contrasts between the parent forms are of a distinctly complex
character.
2. OF THE ALBA-MACEOPHYLLA SERIES
The crosses between alba and macropyhlla were made in July, 1909.
The cross was successful in both directions, and seed was secured from
alba*^ x macrophylla^, which was given the number H 23 , and from the
reciprocal which was given the number H 24 .
When mature the F t plants were tall, 100 to 200 cm., averaging 130
to 160 cm. Habit and leaf shape were in general those of alba. The
corolla was deep pink of about the same shade as that of the F 4 of
the angustifolia-macrophylla series. The variation in height in these
populations possibly indicates a lack of constancy in the alba parent
in this respect. In plate 83, figure 2, is shown an F x plant of IOFjH^.
3. F 2 OF THE ALBA-MACEOPHYLLA SEEIES
In 1911 four F 2 populations were grown, viz., 25 plants each of
11F 2 H 23 P 13 , 11F 2 H 23 P 31 , and 11F 2 H 24 P 0 , and 23 plants of 11F 2 H 24 P 34 .
The four populations, although small, proved to be equivalent in every
respect. The type of segregation was very complex. That of differ-
ences in types of leaves, especially, presented such a series of inter-
gradations as to defy any definite classification. Likewise in height,
there was a continuous series of forms from the tallest to the shortest.
A rough classification was, however, made for purposes of reference
into tall, medium, and short. An excellent illustration Of the segre-
gation for this character is shown in plate 85, figure 1, which shows
506 University of California Publications in Botany [Vol. 5
two adjacent plants of 11F 2 H 24 P.; 4 , one tall and of the general habit
of alba, and the other short and of the general habit of macropliylla.
The classification for height is given in table 18. Obviously no satis-
factory Mendelian formulation can be deduced from these data.
As regards flower color, however, the classification is more definite.
Four more or less distinct shades were distinguishable, viz., red, pink,
light pink, and white. The pink and light pink shades merged into
each other, consequently they have not been separately recorded in
table 18. Bearing in mind the previous behavior of red and pink, as
shown in the angustif oKa-macrophylla and calycina-virginica series,
TABLE 18
F 2 SEGREGATION IN THE A LBA-MA CROPH YLLA SERIES.
Stature
Flower Color
Garden numbers
tall
medium
short
red
pink
white
11F 2 H 23 P 13
11
6
8
3
14
8
11F,H 23 P 31
13
6
6
4
12
9
11F 2 H 24 P 6
7
10
8
3
15
7
11F 2 H 24 P 34
6
8
9
6
13
3
Totals
37
39
31
16
54
27
it would appear that we are here dealing with dihybrid populations
in which a pair of allelomorphs for color versus white is concerned in
addition to that pair upon which the contrast of pink versus red was
found to depend. The pair of allelomorphs for the pink versus red
contrast has been represented by R and r, respectively. If we repre-
sent the contrast of color versus white by W and w, respectively, the
two parents in this series would possess the following genotypes :
Alba = RRww
Macropliylla = rrWW
The light pinks of the previous series would then be RRWW, and the
factor R might be regarded as a dominant diluter. According to this
formulation, F 1 of the alba-macrophylla series would be RrWw, pink,
and \~ should segregate in the ratio 3 red : 9 pink : 4 white. The
expectajl result in the classification of ninety-seven plants in whole
numbersVf 18 red : 55 pink : 24 white. Agreement is thus fairly close.
A check on the results above noted for the 1911 sowings of the F 2
population was made by growing in 1916, five additional F„ popula-
1922]
Setchell-Goodspeed-Clausen : Nicotiana Tabacum
507
tions of the same series, viz., 16F 2 H 23 P 5 ; 16F 2 H 23 P 32 ; 16F 2 H 23 P 34 ;
16F,H 24 P 2S ; and 16F 2 H 24 P 33 . The segregation in the resulting popu-
lations is recorded, in table 19.
The method of studying these flowers was the more accurate one
previously described in connection with later generations of the
angustifolia-macrophylla series. In the classification of flowers it was
noted- that reds and whites were sharply distinguishable from pinks.
The pinks were of many different shades ; some very light, others rela-
tively dark, corresponding to the range obtained in the angustifolia-
macropliyUa series. However, in these populations the range of vari-
TABLE 19
F 2 SEGREGATION IN 1916 SOWINGS OF ALBA-MACROPHYLLA SERIES.
Garden numbers
Red
Pink
White
Totals
16F 2 H 23 P 5
11
18
11
40
16F 2 H 23 P 32
12
19
11
42
16F 2 H 23 P 3 4
8
24
9
41
16F 2 H 24 P 28
5
34
11
50
16F 2 H 24 P 33
7
29
14
50
Observed
43
124
56
223
Expected
42
125
56
223
ation of pink appeared to be greater and the intergradations more
gradual than in that series. In the whites there was also evidence of
differentiation into classes depending upon the amount of yellow or
creaminess in the flowers. Some of the whites appeared to belong to
a clear white albino class, but most of them had a distinctly creamy
tinge. The observed segregation in these populations was in almost
exact agreement with the formulation advanced above.
4. F 3 AND SUBSEQUENT GENERATIONS OF THE ALBA-MACROPHYLLA
SERIES
In table 20 we have summarized the behavior of the F 3 populations
as respects color of flowers and height of plant. Of the five red F 2
plants from which F 3 populations were grown, three proved to be
homozygous for red and one proved to be a heterozygote of the^genetic
constitution rrWw. Of this latter selection two sowings wpe made,
one in 1912 and another in 1913. The combined results Jrom these
two sowings, 35 red : 14 white, are in fair agreement with Mendelian
508 University of California Publications in Botany [ VoL - 5
expectation. The other population exhibited an anomalous type of
segregation, and gave 2 red : 23 white. It is unfortunate that this
line was not investigated further, but the results probably are due to
an experimental error.
TABLE 20
F 3 SOWINGS OF THE A LBA-MA CROPH YLLA SERIES.
F2 Phenotypes
Garden
Numbers
Flower Color
Stature
Flower
Color
Stature
Red
pink
white
short
tall (or
medium)
Tall (orM)
I2F3H03P13P3
19
6
25
Short
1 / H 1 H no t 11 r 1
22
22
Red
Sh't(orM).
12FiH9iP<..Pn
AArfA j A J. J 3 J. A\A. 17
25
4
21
Tall
12F3H23P31P22
24
4
20
Tall
1 / H 9 H .)■> \ 11 r.it:
aa^a i)'-i-2o A 61*- 2o
2
23
1
24
Tall
16FiH,iP n P,
A v -' A 1) 4 - 1 i J 1 Id 4 - J
. 16
8
Tall
12FiH-nPnPn
2
14
6
8
10
lYXeclium
^FiHo^PnP,^
0
1 9
7
99
Tall
12F 3 H 23 P 31 P 7
6
14
5
25
Tall
12F 3 H 23 P 31 P 19
10
9
4
23
Pink
Medium
Tall
12F 3 H2 3 P 3 lP20
12F 3 H 24 P C P 5
6
3
12
22
5
, 4
19
25
Short
12F 3 H 24 P 34 Pi 8
5
13
7
24
1 '
Tall
12F 3 H 24 P 3 4P 2 o
20
5
25
Tall
16F 3 H 24 P 3 4P 2 o
13
4
Tall
12F 3 H 23 P 13 P 14
25
25
Tall
12F 3 H 23 P I3 P 15
25
25
Short
12F 3 H 23 P 13 P 24
25
25
White
Tall
12F 3 H 24 P 6 P 2
24
24
Short
12F 3 H 24 P 6 P 3
25
4
21
Tall
12F 3 H 24 P 6 P 4
23
23
Short
12F 3 Ho 4 P 34 P 23
1
23
25
Short
13F 3 H 23 Pi 3 P2 4
10
10
Short
13F 3 H 24 P 34 P 23
10
10
Eight families of F ;i plants were grown from pink F 2 's. Of these
F 2 plants six proved to belong to the RrWw genotype. The totals
from these six populations, viz., 35 red : 74 pink : 34 white, are in fair
agreement with the dihybrid ratio 3 red : 9 pink : 4 white. One of
the other populations gave 3 red : 22 pink. It was probably the result
of sowing seed from an F„ plant of the genetic constitution RrWW
which should give 3 pink : 1 red. The observed segregation ratio is
not good\ but the numbers are small. Two sowings of F-jH^P^Pop
gave totals of 33 pink : 9 white. The F 2 plants in this case must have
been of the genetic constitution RRWw; in which case expectation
would be 3 pink : 1 white. No selection was observed to breed true
1922] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 509
for pink in F 2 . This, however, is not inexplicable, for only one in
nine among the F, pinks should belong to the ERWW genotype.
Sowings were made from seven white F 2 plants. Among 190 plants
so produced there was one pink flowering individual. It surely rep-
resents some kind of experimental error. We may say, therefore, that
for flower color the formulation advanced to account for the F 2 segre-
gation ratio, also accounts for the behavior observed in the various F 3
populations.
"We have reported the data on height in table 20, largely in order
to show that this character, although obviously dependent on factor
differences, is so complex as not to permit of a simple qualitative
treatment. Thirteen F 3 sowings from tall F 2 plants gave ten popu-
lations showing only tall plants. Two of the remaining populations
showed segregation into 31 tall (and medium) : 13 short. One popu-
lation consisted entirely of short plants. The classification of the F,
parent of this plant as "tall" was noted as doubtful at the time, the
note "or medium" being appended. Two- populations were grown
from F 2 plants of medium height. One of these populations was uni-
formly of low stature; the other showed segregation into 19 tall (and
medium) : 4 short. Six populations were grown from F 2 parents,
four of which apparently bred true for low stature, the other two
showed segregation into tall (and medium) or short in the ratio 42 : 8.
It is interesting to note that at the time of classification the parents
of these two later populations were classified as short (or medium),
indicating a doubt as to proper classification. More definite data will
be necessary before a satisfactory formulation of these height differ-
ences can be made, but certain of our results seem to indicate that
there is one allelomorphic pair which has a rather marked effect on
stature, and that there are other subsidiary pairs of factors which
have less marked effects.
Only one line in this alba-macrophylla series was carried out to
subsequent generations to demonstrate the possibility of fixing char-
acter complexes from a hybrid. It was a low stature white flowering
line. In F 4 , 100 plants of 13F 4 H 24 P 34 P 23 P 2 bred true to low stature
and white flower color. The population was uniform, the plants ex-
hibited the general habit of macrophylla rather than that of alba; and
the leaves were the same shape as those of macrophylla, but they were
slightly rugose, although not so much so as those of alba. In F ri , two
populations of 25 plants each were grown, viz., 14F 5 H 24 P J fP 2:! P 2 P 47
and 14F,,H„ 4 P 34 P 23 P 2 P 83 . No differences were detectable between these
two populations, and the characters exhibited were those we have noted
U. OF ILL Li3.
510 University of California Publications in Botany [Vol. 5
for F 4 . In F 6 10 plants each of 15F G H 24 P :!4 P 23 P 2 P 47 P 5 and 15F 6 H 24
P34P 2 3P 2 P 83 Pi2 and in F 7 10 plants each of 16F 7 H 24 P 34 P 23 P 2 P„,P 12 P 8
and 16F 7 H 24 P 34 P 23 P 2 P 47 P 5 P 8 were grown. In both cases the parallel
populations were equivalent and the characters exhibited and described
in F 4 remained constant. Plate 85, figure 2, is a good illustration of
the type of this family as fixed. A photograph of the original F 2
plant, from which the family descended, is reproduced in plate 85,
figure 1. It will be noted that the derivative represents a fixation of
the characters of the original F 2 selection, and that no important seg-
regation occurred in it either in F 3 or in subsequent generations.
5. DISCUSSION OF RESULTS OF THE ALBA-MACROPHYLLA SERIES
Here again, as in the calycina-virginica series, no extended discus-
sion of results is necessary. Obviously the differences separating the
two varieties are of a complex nature genetically as in the two previous
cases. The series demonstrates the existence of another pair of allelo-
morphs for flower color in this group of Tabacum varieties, viz., Ww,
and the part played by it in the production of both red and light pink
flower color has been determined. The height contrast again proves
to be too complex for qualitative Mendelian formulation. As in the
previous cases, the establishment of stable recombination derivatives
proved to be a simple task.
VI. GENERAL CONCLUSIONS
We shall limit the discussion of these results to three main topics
upon which these investigations seem to have thrown some light: (1)
the origin and interrelationships of varieties of Tabacum; (2) the
methodology of Mendelian analysis in Tabacum; and (3) Mendelian
heredity in Tabacum.
1. ORIGIN AND INTERRELATIONSHIPS OF VARIETIES OF TABACUM
As a result of extensive studies of a considerable assemblage of
Tabacum varieties, Comes (1905) came to the conclusion that the
s Tabacum could be subdivided into six fundamental varieties:
a. var. fructicosa Hook.
J), var. la mi folia (W.) Comes,
fc. var. virginica (Agdh.) Comes,
cf^-var. brasiliensis Comes.
e. var. havanensis (Lag.) Comes.
/. van macrophylla Shrank.
1922]
Sctchell-Goodspeed-Clausen : Nicotiana Tabacum
511
Inasmuch as practically every Tabacum variety shows combinations
of characters of two or more of these fundamental varieties, Comes
assumed them to have been derived mostly through hybridization be-
tween the fundamental varieties, and he proceeded from purely morph-
ological studies to classify the different commercial varieties on the
basis of their supposed hybrid derivation. Anastasia (1906), who
has criticized this scheme of Comes very severely, reduced the number
of fundamental varieties to four, striking out fructicosa and lancifolia
from Comes' list, and substituting purpurea for macrophylla. Al-
though disagreeing as to the fundamental varieties, Comes and Ana-
stasia seem to agree in referring existing varieties to derivation, mostly
through hybridization, from a relatively small number of fundamental
varieties.
The Howards (1912) object to the mode of classification of Comes
and Anastasia, and point out as a result of their studies of types of
Indian tobaccos that no attempt at classification based on derivation
can be considered seriously unless supported by actual experimental
studies. In her later paper in particular Miss Howard (1913) shows
that segregation products may be obtained through hybridization
which transcend the limits set by the parents. The Howards propose
a scheme of classification based primarily upon leaf and habit char-
acters, and they adopted this morphological system purely as a pro-
visional means for facilitating identification and reference among the
numerous forms of Indian tobaccos.
Our results agree with those stated by the Howards, and we raise
the same objection to schemes of classification such as Comes and
Anastasia have advocated. Any scheme of classification based on
morphological considerations alone cannot well meet with the approval
of geneticists, for it does not take into account genotypic differences
which exist among forms of similar morphological appearance. Thus
it is possible, as Miss Howard points out, by crossing different mem-
bers of a given group to obtain segregation products which belong in
an entirely different morphological group in the scheme of classifica-
tion. In particular she points out that "petiolate" forms have been
produced as segregation products from two "sessile" parents, yet
"petiolate" and "sessile" have been used as primary indexes for
classification of tobaccos into groups.
The difficulty from the genetic point of view with any classification
of Tabacum varieties is the same as that which is met witll in the
species as a whole and viewing the entire assemblage of its varieties,
classification of varieties of other polymorphic species
512 University of California Publications in Botany [Vol.5
there is evidently in Tabacum, to those who accept current interpre-
tations of heredity, a series of allelomorphic contrasts, the number of
which cannot even be guessed, but which need not perhaps be more nu-
merous or striking than those which have been discovered in Drosophila.
But whereas in Drosophila the factors have been kept in stocks in-
volving for the most part single factor differences from a common wild
type, in Tabacum, and in other cultivated crop plants such as barley,
maize, oats, rice, wheat, etc., these factor differences have been shuffled
about through long periods of cultivation until existing varieties are
no longer related clearly to a common form or to each other. In some
instances in such groups certain factor differences have a more strik-
ing visible effect than in others. In such instances we have an obvious
mode of classification based not upon number of factor differences so
much as upon the striking character differences which arise from
certain factor contrasts. Thus in barley we have the classification of
varieties advocated by Harlan (1918) based upon recognition of a
number of major morphological distinctions, some of which at least
have been clearly analyzed in Mendelian fashion ; and the same prin-
ciple has been recognized in the classification of varieties of maize,
where it has led to the absurdity of erection of a heterozygous form,
podded maize (vide Collins), as one of the primary group distinctions.
In some instances, doubtless, the sorting of factors may give rise to
certain recombinations which are more favorable to life processes than
others, as Muller has pointed out in another connection, and such
genotypes may act as centers around which groups of varieties may
be built up, thus giving rise to more or less obvious grouping of varie-
ties. The attempt to base a system of classification upon reference to
certain fundamental types does not, however, promise much simpli-
fication of the difficulty; moreover, such an attempt rests upon the
rather naive assumption that it is unnecessary to account for the
fundamental types.
From a genetic standpoint, therefore, it would appear that in
attacking the problem of classification and interrelations of varieties
in a polymorphic species the major premise should be a recognition
of the fundamental equivalence of every homozygous genotype. Start-
ing from this premise a system of dichotomy beginning with those
factor contrasts which produce the most striking, visible effects and
proceeding to those of lesser effect might be set in operation. Such a
systentobviously would in certain eases separate some similar varie-
ties intcfcseparate groups, and would lead to recognition of group
differences without obvious morphological distinctions, but the system
1922] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 513
would have a real significance, and the relationships indicated by it
would be fundamental ones. It is, however, necessary to have a much
more extensive knowledge of Mendelian heredity in Tabacum than we
have at present before such a system can be formulated.
2. METHODOLOGY OF MENDELIAN ANALYSIS IN TABACUM
Prom the Mendelian side there are certain obvious facts associated
with Tabacum as a species. In the first place, as we have stated before,
the species is highly polymorphic. A large and striking assemblage
of varieties exists, the most extreme of which hybridize readily and
give fully fertile hybrids and full fertility in their derivatives. A
few teratological forms are known in which fertility is somewhat re-
duced, but the above generalization does not far overstate the facts.
The species is, moreover, so highly polymorphic that with respect to
any given character a representative collection of varieties may be
arranged in a series connecting the most extreme expressions of that
character by imperceptible steps. Thus in flower color we have repre-
sented in the collection of varieties of the University of California
Botanical Garden dark red, red, light pink, pinkish, and white, and
descriptions occur in the literature which indicate the existence of
further shades of red connecting these. Now flower color is a rather
definite character, comparatively speaking, for it appears to be little
affected by ordinary environmental conditions. In many polymorphic
forms, such for example as maize, there are a large number of such
definite characters, and as a consequence studies of inheritance in
these forms have resulted in definite Mendelian analysis of many char-
acter differences. But in Tabacum unfortunately most of the char-
acters involve quantitative elements, and these with few exceptions
depend so largely for their particular expression upon environmental
conditions that it becomes a difficult matter in a segregating population
to distinguish between those differences which are inherent and refer-
able to the genotype and those which have come about through the
action of extrinsic forces. And yet our assemblage of tobacco varie-
ties indicates clearly that there are genotypes which give rise to all
possible expressions in these characters. Here we find the reason for
the present backward state of knowledge of inheritance in Tabacum,
for while there have been numerous investigations which indicate
clearly that the Mendelian mode of transmission may be followed in
all these character differences, yet there are very few investigations
which have resulted in the precise type of factor analysis characteristic
514
University of California Publications in Botany
[Vol. 5
of investigations with other forms, specific mention of which is un-
necessary.
The general features of inheritance in Tabacum varietal crosses
are plain enough. The results of our investigations in this connection
agree throughout with the conclusions which Miss Howard drew from
her studies. "When we are dealing with complex differences, the F 1
is commonly intermediate in character expression between the two
parents. Not only is this true as respects the F 1 plant as a whole but
it is also true for individual characters. The F 2 commonly consists
of a varied assemblage of forms covering the range between the two
parents, or even not uncommonly presenting products not included
in the range between the two parents. So many and of such variety
are the forms obtained that accurate classification is entirely out of
the question. But in F 3 and in subsequent generations segregation,
even for characters commonly regarded as quantitative, sometimes
occurs in distinct discontinuous classes in marked contrast to the inter-
grading series of forms obtained in F 2 . This is shown particularly
well in our analysis of leaf base factors, for in this case we have been
able to adopt a qualitative mode of attack on one of the features which
contributes to leaf shape. If such an analysis proves successful in
one instance, there seems to be little reason why it should not be ex-
tended to others. There is, therefore, additional evidence in this suc-
cessful application of the mode of qualitative analysis to quantitative
characters in support of the oft repeated contentions of East (1913),
Hayes (1912), Hayes, East, and Beinhart (1913), Miss Howard
(1913), and others that fundamentally the same mode of inheritance
holds for quantitative characters in tobacco as for qualitative ones.
The distinction between the two classes of characters is purely an
artificial one erected for the purpose of convenience in formal treat-
ment, and at most depending merely upon an increase in complexity
of the factor relations involved and on the greater fluctuation of the
characters in response to environmental differences.
The question remains to be discussed whether semiquantitative
characters admit of a qualitative mode of analysis, and if so, how?
Miss Howard (1913) as a result of her extensive studies of inheritance
in Indian tobaccos concludes that the easiest way to determine the
principles underlying inheritance in these forms is to establish as
many extracted homozygous intermediate forms as possible. The estab-
lishment of such forms in themselves, however, is only a step in the
Mendelian analysis of the differences. Such forms are, as might have
been expected on theoretical grounds alone, less different from one
1922] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 515
another and from the parents than the original parents are from each
other. Moreover, our experiments show that as a result of simplifi-
cation of the factor differences the derivative strains crossed with each
other or with the parents give F 2 progenies which often exhibit clear-
cut segregation in characters which showed intergrading series in the
original P 2 population. In other populations, however, from crosses
between derivatives, the populations still exhibit perplexing com-
plexities which make classification difficult and uncertain. In such
cases we could again resort to the method of establishing intermediate
derivatives from them; but if the number of factors concerned in a
given character is even moderately large, as is certainly the case with
many of these quantitative characters, the number of genotypically
different derivatives which may be secured becomes so great as to make
the method impracticable.
Our experience indicates that the successful factor analysis of these
quantitative character differences depends not only upon getting what
Castle (1919) has called the residual heredity equivalent throughout
the population, but also in establishing the proper kind of residuum
which will most emphasize the character differences associated with
the pair of factors or pairs of factors under investigation. The prob-
lem may be illustrated crudely by considering the pair of flower color
factors Rr. If the residuum should contain PP, the effect of which
is described below, segregation would give PPRR, PPRr, and PPrr.
In character expressions these three different genotypes would doubt-
less all be of various shades of dark red, difficult or impossible of ac-
curate separation. With such a residuum, therefore, it would be im-
possible to investigate satisfactorily inheritance in the factor pair Rr.
But if we should substitute pp for PP in the residuum, the segregation
products would be ppRR and ppRr, which would be pink, and pprr,
which would be red. Here the segregation would be sharp and dis-
tinct, and there would be practically no difficulty in classification.
How complex such interrelations can be has been shown most clearly
by Bridges (1919) in his account of specific modifiers of eosin in
Drosophila. As Bridges shows it would easily be possible to obtain
populations of Drosophila defying classification, but by keeping the
factors separate and studying their character effects with known
residual genotypes, it has been possible to determine and locate the
factors involved. Doubtless much of the extraordinary success of
Mendelian analysis in Drosophila has been due to the fact thatjractor
differences arose under conditions such that the residual araotype
gave no difficulty ; whereas in crop plants, the geneticist starts with
516
University of California Publications in Botany
[Vol. 5
long established diverse types, evidently related to one another in
fundamentally the same manner as are the various Drosophila mutants,
but more complexly, and from these complex assemblages he must
unravel the tangled skein of heredity.
There are, however, other and perhaps quicker ways of establishing
a uniform and favorable residual heredity than that of securing and
testing homozygous extractives, and these may be employed in certain
special cases. Thus, if it be desired to study the relationship of the
pair of factors Ss for the petioled versus sessile condition, it should
be possible to proceed by crossing back the F x of angustifolia x macro-
phylla, for example, to macrophylla, selecting the petioled forms from
the back cross for again crossing back to macrophylla, and continuing
the process until clear-cut segregation was obtained. Such a mode
of procedure should establish a residual genotype equivalent to that
of macrophylla itself, and should thereby enable the student event-
ually to. study the effect of substituting SS for ss in the macrophylla
genotype. In tobaccos technical details make it particularly easy to
adopt such a procedure, but it is useless to speculate further 'Upon its
results until it shall have been attempted.
3. MENDELIAN HEREDITY IN TABACUM
From the standpoint of factor analysis, we have demonstrated
clearly in the foregoing pages, the existence of a number of distinct
pairs of factors. Two of these affect flower color, one flower form,
and three affect the character of the leaf base. The particular effects
of the opposing members of these pairs of factors and the interrela-
tions which they exhibit so far as these have been investigated have
been set forth in the discussions which follow the description of each
of the three series of hybrids. Although evidently many other factor
differences were concerned in these studies, and remain for further
investigation, the results which we have described make a beginning
toward a more accurate knowledge of Mendelian heredity in Tabacum.
So far as our results furnish any data on the question, the six
pairs of factors isolated exhibit no linkage relations. The data here
are far from complete, but the results are in accordance with theory.
According to "White (1912), there are twenty-four pairs of chromo-
somes in NicoHana. Assuming for the sake of discussion that each
of these pairs of chromosomes bears a set of factors comparable in
mimblis to any other pair, then the chances of finding linkage when
only six pairs of factors are studied is very slight. This large number
I 922 ] Setchell-Goodspced-Clausen: Nicotiana Tabacum 517
of pairs of chromosomes may account for the ease with which recom-
bination pure lines were established. Even with a large number of
factor differences, such as evidently distinguish these Tabacum varie-
ties, the chances are slight with so many pairs of chromosomes that
linkage will enter in as a factor to cause the continued preservation
of a heterozygous condition as a consequence of selection for a certain
set of characters.
It remains to consider those portions of the Nicotiana literature
which deal specifically with the Mendelian inheritance of the charac-
ters which we have investigated, and to harmonize our results with
those which have been reported previously. Unfortunately there have
not been many investigations in Tabacum which have been prosecuted
far enough to arrive at a definite factor analysis of the differences
under consideration. The investigations of Miss Howard (1913),
promise of the continuation of which has not thus far been fulfilled,
in general confirm those which we have presented in this paper. On
the strictly analytic side, however, Miss Howard did not carry her
work very far. This doubtless was due to the difficulty of making a
factor analysis of the characters which she selected for study, viz.,
(1) time of flowering, (2) height of stem, (3) arrangement of the
leaves on the stem, (4) length of the decurrent portion of the lamina,
(5) venation of the leaf, (6) leaf shape, and (7) undulation of the
surface and margin of the leaf. For most of these characters she
demonstrates, by the presentation of numerical data in some cases
as far as F 4 , the probability of the character differences in ques-
tion depending upon multiple factor differences. In the case of height
certain of her cultures strongly suggest the existence of a pair of
allelomorphs, which has a relatively great effect, for in some of her
cultures there are definite discontinuous height differences. For the
inheritance of length of the decurrent portion of the lamina Miss
Howard postulates the existence of at least three or four distinct pairs
of factors. As respects leaf base, she records the synthesis of petiolate
types from sessile parents, observing in two cases a simple 1 :2 :1 segre-
gation into petiolate : intermediate : sessile. As respects corolla color,
she records one F 2 population from pink x very pale pink fading into
white which consisted of 72 pinks of various shades to 45 whites, but
some of the palest pinks were indistinguishable from white. She found
evidence of grouping among the pinks, and postulates the existence
of two factor differences to account for it. The investigations which
we have reported do not throw light upon the factor constitution of
the very pale pink varieties with which Miss Howard worked. Our
518 University of California Publications in Botany [Vol.5
varieties angustifolia and virginica have lively pink flowers. Of the
paler pinks or "pinkish" forms we have a representative in our N.
Tabacum var. Cavala, U. C. B. G. 72/05, which has flowers distinctly
lighter in color than those of angustifolia or virginica. Our petiolate
forms also seem to he of different constitution from those with which
Miss Howard worked, for she presents evidence to show that hers are
combinations of recessive factors and that they breed true whenever
they occur as segregation products, whereas our petiolate forms often
gave plants with sessile leaves as segregation products. We have,
however, secured evidence that some distinctly short petiolate forms
arise from sessile ones, perhaps by modifications of the aurictlata
leaf type in the direction of stripping the auricle and lower portion
of the lamina from such leaves, but our results are not yet definite
enough to permit of rigid formulation. Further investigation of the
relationships of the various petiolate forms is necessary.
As respects flower color Allard (1919) has presented some inter-
esting data which at first sight appear to contradict those which we
have presented. Allard found that carmine x pink gave F t carmine and
F 2 3 carmine : 1 pink. The back crosses gave consistent data. Thus
Fj carmine x carmine parent gave all carmine, and F x carmine x pink
parent gave 1 carmine : 1 pink. In F :! pink segregants bred true for
pink, and carmine either bred true for carmine or gave again 3 carmine
:1 pink. The difficulty here is that our red is not genetically identical
with Allard 's carmine. Our flowers of macrophylla and calycina at
full expansion show a color lying between rose red and pomegranate
purple of the Ridgway color scale. This color, which we have called
red for the sake of brevity, is very close to carmine, but we have an-
other flower color, which we call dark red, represented by N. Tabacum
var. macrophylla purpurea, which is probably identical with the Giant
Red flowering tobacco which Allard used in his experiments.
"We have made some preliminary tests of this dark red, and find
that it behaves differently from red. Crossed with our white it gives
dark red in F 1; instead of pink as was obtained from red x white.
Since our white carries the factor R, which is responsible for the
production of pink flower color, dark red must differ from pink in a
dominant factor. If we call this factor pair Pp, then our various
colors of tobacco would have the following genotypes:
Dark red
Red
Pink
White
WWRRPP
WWrrpp
WWRRpp
wwRRpp
I 922 ] Setchell-Goodspeed-Clausen: Nicotiana Tabacum 519
Obviously this formulation would account for Allard's results with-
out contradicting those which we have presented, but inasmuch as our
experimental evidence is not yet complete we refrain from any further
discussion of the consequences of this scheme save one. Allard presents
certain data for a cross of carmine x white which gave in F 1 light
carmine, and in P 2 3 colored : 1 white, the colored being various shades
of carmine and pink. Allard's discussion of this case is somewhat
mixed, but he evidently erroneously expected a simple monohybrid
segregation of the 1:2:1 kind. That more than one factor is con-
cerned in the cross is clearly shown by the results of crossing some of
the extracted whites with pink varieties. The results of three such
crosses gave :
1. Pink (Maryland Mammoth) x Extracted white 36 carmine : 18 pink
2. Extracted white x Pink (Maryland Mammoth) 20 carmine : 23 pink
3. Pink (Conn. Broadleaf) x Extracted white 12 carmine : 39 pink
Totals 68 carmine : 70 pink
In (1) above we have combined in the carmine class 17 carmine and
19 somewhat lighter than carmine.
If we consider a cross of dark red x white according to the genetic
formulation given above, the F x should be dark red, and F 2 should
consist of 9 dark red : 3 pink : 4 white. Doubtless the pinks and the
dark reds would exhibit various shades, but the three classes should
be distinct. If we combine "carmine" and "lighter than carmine"
to form a carmine class and dark and light pink to form a pink class,
Allard 's P 2 data reduce to the following form :
149 carmine : 64 pink : 65 white.
This ratio compares very favorably with a 9 : 3 : 4 expectation, viz. :
157 dark red : 52 pink : 69 white.
No F 3 results from sowings from colored F 2 plants are given, but the
single F 2 white, which gave when crossed with pink approximately
equal numbers of carmine and pink flowering plants, is accountable
for as of the genotype wwRRPp. Further investigations are in pro-
gress for the purpose of determining precisely the relation of dark
red and pinkish to the red, light pink, and white colors reported upon
in this paper.
There are other references in the literature to Mendelian inherit-
ance in Tabacum, but inasmuch as these do not bear upon the
characters which we have attempted to analyze it does not appear
necessary to discuss them at this point.
520
University of California Publications in Botany [Vol. 5
VII. SUMMARY
Studies of three intervarietal crosses in Tabacum demonstrate that :
1. All the differences between varieties of Tabacum can be analyzed
in a Mendelian fashion, if sufficient refinement in methods be intro-
duced.
2. Stable recombinations of parental characters can readily be
obtained with three or four generations of self-fertilization.
3. Characters outside the range between the parents are sometimes
produced following hybridization, and these may be readily established
in stable lines by self-fertilization.
■4. The petioled leaf base of angustifolia and the sessile leaf base
of macrophylla differ in at least three pairs of factors.
5. A single factor difference exists between normal and split hose-
in-hose flowers.
6. Two pairs of factors account for the relation existing between
red, light pink, and white flower color. A third pair of factors is
necessary to account for dark red.
On the theoretical side it has been pointed out that :
1. Derivation of relationships and erection of systems of classifi-
cation after the manner of Comes and Anastasia cannot be relied upon
unless supported by experimental evidence.
2. An adequate scheme of classification should be based upon iden-
tities and dissimilarities in the genotypes, irrespective of the derivation
of the forms in question.
3. Mendelian analysis in Tabacum requires that special attention
be paid to residual portions of the genotype, so that the factor differ-
ences under consideration act in a stable residuum most favorable for
emphasis of the character differences under investigation.
LITERATURE CITED
Allard, H. A.
1919. Some studies in blossom color inheritance in tobacco, with special
reference to N. sylvestris and N. Tabacum. Am. Nat., vol. 53, pp.
79-84.
Anastasia, G. E.
1906. Le varieta tipiche della Nicotiana Tabacum L. Scafati.
Bridges, C. B.
1919. Specific modifiers of eosin eye color in Drosophila melanogastcr. Jour.
Exp. Zool., vol. 28, pp. 337-384.
1922] Setcliell-Goodspeed-Clausen: Nicotiana Tabacum 521
Castle, W. C.
1919. Piebald rats and the theory of genes. Proc. Nat. Acad. Sci., vol. 4,
pp. 126-130.
Collins, G. N.
1917. Hybrids of Zea ramosa and Zea tunicata. Jour. Agric. Ees., vol. 9,
pp. 383-396.
Comes, O.
1899. Monographie du genre Nicotiana comprenant le elassement botanique
des tabacs industriels. Atti del E. Instituto d 'Incoraggiamento di
Napoli, ser. V, vol. 1.
1905. Dello razze dei tabacchi filogenesi, qualita ed uso. Ibid., vol. 57.
East, E. M.
1913. Inheritance of flower size in crosses between Nicotiana species. Bot.
Gaz., vol. 55, pp. 177-188.
GOODSPEED, T. H.
1912. Quantitative studies of inheritance in Nicotiana hybrids. Univ. Calif.
Publ. Bot., vol. 5, pp. 87-168.
Goodspeed, T. H., and Clausen, R. E.
1917. The nature of the Pj species hybrids between Nicotiana sylvestris and
varieties of JV. Tabacum. Univ. Calif. Publ. Bot., vol. 5, pp. 301-346.
Harlan, H. V.
1918. The identification of varieties of barley. U. S. Dept. of Agric, Bull.
622, pp. 1-32.
Hayes, H. K.
1912. Correlation and inheritance in Nicotiana Tabacum. Conn. Agric. Exp.
Station, Bull. 171, pp. 1-45.
Hates, H. K., East, E. M., and Beinhaet, E. G.
1913. Tobacco breeding in Connecticut. Conn. Agric. Exp. Station, Bull.
176, pp. 1-68.
Hasselbring, H.
1912. Types of Cuban tobacco. Bot. Gaz., vol. 53, pp. 113-126.
Howard, A., and Howard, Gabrielle L. C.
1910. Studies in Indian tobaccos. No. 2, The types of Nicotiana Tabacum L.
Mem. India Dept. Agric. Bot. Series, vol. 3, pp. 59-176.
Howard, Gabrielle L. C.
1913. Studies in Indian tobaccos. No. 3, The inheritance of characters in
Nicotiana Tabacum L. Ibid., vol. 6, pp. 25-114.
MULLEH, H. J.
1918. Genetic variability, twin hybrids, and constant hybrids in a case of
balanced lethal factors. Genetics, vol. 3, pp. 422-499.
RlDGWAY, BOBERT
1912. Color standards and color nomenclature.
Setchell, W. A.
1912. Studies in Nicotiana, I. Univ. Calif. Publ. Bot., vol. 5, pp. 1-86.
White, O. E.
1913. Bearing of teratological development in Nicotiana on theories of
heredity. Am. Nat., vol. 47, pp. 206-229.
1914. The history of Nicotiana, II. An account of the heredity and envi-
ronment of a family of tobacco plants. Brooklyn Bot. Garden
Leaflets, Series 2, No. 12.
EXPLANATION OF PLATES
A special note is due the illustrations in this paper. The line drawings were
made by Miss Anna Hamilton and Miss Helen M. Gilkey. Special attention was
paid to accuracy in proportions and details. No attempt, however, was made
to represent the characteristic Nicotiana pubescence. The photographs require
no special mention save that sometimes the garden number given in the legend
does not correspond with that given on the label in the photograph. The dif-
ference is due to a change in system of numbering used in F 3 and in subsequent
populations. In this paper, in order to avoid confusion, garden numbers from
the beginning have been made to conform to this change. The legends of
all the plates have been made more complete than is usual in order to facilitate
cross-reference and to enable the reader to grasp their essential significance more
readily.
PLATE 55
Fig. 1. Nicotiana Tabacum var. angustifolia, U. C. B. G. 68/07. A typical
plant of angustifolia at the height of its blooming period. The laterals over-
topping the central' axis and the long-petioled stcnophylla form of leaf are
especially to be noted. The drooping of the leaves is very characteristic of this
variety.
Fig. 2. Nicotiana Tabacum var. macrophylla, U. C. B. G. 22/07. A typical
plant of macrophylla at the height of its blooming period. Note especially the
stout laterals overtopping the central axis and the sessilifolia type of leaf.
[522]
1
1
I
i
PLATE 56
Nicotiana Tabacum var. angustifolia, U. C. B. G. 68/07. Line drawings of
typical details of angustifolia. In the upper right-hand coiner the characteristic
straplike sessile leaf or bract of the inflorescence. Upper left, details of bud,
flower, and capsule. Lower right, details of pistil and stamens. Lower left, the
typical long petioled stenophylla leaf of angustifolia. Leaves X % ; flowers and
capsules natural size.
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN J PLATE
PLATE 57
Nicotiana Tabacum var. macrophylla, U. C. B. G. 22/07. Line drawings of
typical details of a plant of macrophylla, showing floral details and the extreme
variations in leaf size and shape on the plant. Leaves X % ; flowers and cap-
sules natural size.
[526]
»
UNIV. CALIF. PUBL. BOT. VOL. 5 [ S ETCH E LL-GOODS PE E D-C LAUSEN ] PLATE 57
PLATE 58
Fig. 1. Nicotiana Tabacum var. angustifolia, U. C. B. G. 68/07. Typical leaves
of angustifolia of the stenophylla type showing the range of variation on a single
plant.
Fig. 2. Nicotiana Tabacum var. macrophylla, U. C. B. G. 22/07. Typical leaves
of macrophylla of the sessilif olia type showing the range of variation on a single
plant.
[528]
PLATE 59
Angustifolia-macropftylla series, F 1 leaves.
Fig. 1. Typical leaf of IOF^jPs,,, an F 1 of the angustifolia-macrophylla
series. Note the short, winged petiole and the clasping auricles.
Fig. 2. Typical leaf of 10F,H 3 P M , a variation from the usual latifolia type
of the F, leaf. Note the shorter petiole, less conspicuously winged condition,
and the almost total lack of auricles.
Fig. 3. Typical leaf of 10F,H 4 P i5 . The petiole is somewhat longer than that
normal for the F,.
Fig. 4. Typical leaf of lOF^P-,,. The petiole here is shorter than that
normal for the F,.
PLATE 60
Portions of inflorescences of N. Tabacum var. macrophylla, N. Tabacum var.
angustifolia and the F, hybrid between them.
Fig. 1. Left, portion of inflorescence of macrophylla, middle, of the F,, and
right, of angustifolia.
Fig. 2. Left, portion of the inflorescence of macrophylla, middle, two of the
F„ and right, of angustifolia.
| 532 |
PLATE 61
August if olia-macrophylla series, Fj plants.
Fig. 1. Photograph of 10F,HjP5 0 , the Fj plant from which the leaf shown
in plate 59, figure 1, was taken.
Fig. 2. Photograph of 10F,H 5 P M , the F t plant from which the leaf shown
in plate 59, figure 4, was taken.
[534]
PLATE 62
Angustifolia-macropliyUa series, line drawings of F t .
Line drawings showing morphological details of the typical Y 1 plant of the
angustifolia-macrophylla series. The garden number of the plant was 10F,H 10 P,.
Leaves X %; flowers and capsules natural size.
[536]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCH E LL-GOODS PE E D-C LAUSE N ] PLATE 62
PLATE 63
Angustifolia-macrophylla series, type 1.
Line drawings of morphological details of F 2 of type 1. The garden number
was IIF.HjPjPj,,. Note particularly the stenophylla type of leaf. Leaves X %;
flowers and capsules natural size.
The F, progeny of this plant consisted of 16 stenophylla of type 1 and 9 lance-
olata of type 14.
[538]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ S ETCH E LL-GOODSPEE D-CLAU SEN ] PLATE 63
PLATE 64
Angustifolia-macrophylla series, type 2.
Line drawings of morphological details of F 2 of type 2. The garden number
was 11F 2 H 2 P ; ,P :;0 . The leaf is of the latifoUa type. Leaves X %; flowers and
capsules natural size.
The F a progeny of this plant consisted of 12 latifoUa, 8 sessilifolia, and 4
auriculata.
[540]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN ] PLATE 64
PLATE 65
Angustifolia-macrophylla series, type 3
Line drawings of morphological details of F 2 of type 3. The garden number
was llF 2 H 2 P 3 Pn. The leaf is of the latifolia type. Leaves X %; flowers and
capsules natural size.
The F 3 progeny of this plant consisted of 4 latifolia and 10 sessilifolia.
[542]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN ] PLATE 65
PLATE 66
Anguntifoliii-nuicrophyUa series, type 4.
Line drawings of the morphological details of type 4. The garden number
was lir 2 H;.PjP 18 . The leaf is an extreme form of the latifolia type. Leaves
X % ; flowers and capsules natural size.
No progeny was grown from this plant.
[544]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN ] PLATE 66
PLATE 67
Angustifolia-maerophylla series, type 5.
Line drawings of morphological details of type 5. The garden number was
11F 2 H J P. 1 ,P 14 . The leaf is of the latifolia type. Leaves X %; flowers and cap-
sules natural size. >
The F 3 progeny of this plant consisted of 24 latifolia and 1 auriculata.
[546]
PLATE 68
Angustif olia-macrophylla series, type 6. I
Line drawings of morphological details of P 2 of type 6. The garden number
was 11F 2 H 4 P 2 P ]8 . The leaf is of the lati folia type. Leaves X %; flowers and
capsules natural size.
The F 3 progeny, of this plant consisted of 5 stenophylla, 17 latifolia, and 4
auriculata plants, but the segregation was not distinct.
[548]
PLATE 69
Angustifolia-macrophyUa series, type 7.
Line drawings of morphological details of F 2 of type 7. The garden number
was 11F ; ,HJ > I1 P 1S . The leaf is of the latifolia type. Leaves X %; flowers and
capsules natural size.
The F„ progeny of this plant was uniformly of the same type as the parent,
and the line bred true in subsequent generations.
[550]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN ] PLATE 69
PLATE 70
Angustifolia-macrophyUa series, type 8.
Line drawings of morphological details of I\ of type 8. The garden number
was llFjELPsP,,!. The leaf approached the auriculata type. Leaves X % ;
flowers and capsules natural size.
The F :! progeny of this plant consisted of 16 sessilifolia and 8 auriculata,
indicating that the plant was an extreme variant of the heterozygous sessilifolia-
auriculata condition.
UNIV. CALIF. PUBL.. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN ] PLATE 70
PLATE 71
Angustifolia-macrophylla series, type 9.
Line drawings of morphological details of F 2 of type 9. The garden number
was 1 1F 2 H 4 P 41 P 8 . The leaf is of the latifoUa type. Leaves X %; flowers and
capsules natural size.
The F 3 progeny of this plant consisted of 18 latifolia and 7 sessilifolia.
[554]
UNIV. CALIF. PUBL, BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN ] PLATE 71
PLATE 72
August if olta-inacropltylla series, type 10.
Line drawings of morphological details of F 2 of type 10. The garden number
was lir 2 H t P 4 ,P n . The leaf was of the auriculata type. Leaves X %; flowers
and capsules natural size.
The F :i progeny of this plant consisted uniformly of auriculata plants.
[556]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCH E LL-GOODSPE E D-CLAU SE N ] PLATE 72
PLATE 73
Angustifolia-macrophylla series, type 11.
Line drawings of morphological details of F 2 of type 11. The garden number
was 11F 2 H 4 P 41 P 9 . The leaf is of the sessilifolia type. Leaves X %; flowers and
capsules natural size.
The F 3 progeny of this plant was uniformly of the same sessilifolia type.
[558]
UNIV. CALIF. PUBL. BOT. VOL, 5 [ SETC H E LL-GOODSPE E D-CLAUSE N ] PLATE 73
PLATE 74
Angustifolia-macrophyUa series, type 12.
Line drawings of morphologicaj details of F 2 of type 12. The garden number
was 11F 2 H 4 P 4 ,P 12 . The leaf is of the loriifolia type. Leaves X % ; flowers and
capsules natural size.
The F a progeny of this plant was uniformly of the same loriifolia type, and
two constant races, one with red and one with light pink flowers, were obtained
from it.
[560]
PLATE 75
Angustifolia-macrophyUa series, type 13.
Line drawings of morphological details of F 2 of type 13. The garden number
was 11F 2 H 2 P 3 P 44 . The leaf is of the lanceolata type. Leaves X %; flowers and
capsules natural size.
The F, progeny of this plant was uniformly of the same lanceolata type.
[562]
/
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-C'-AUSEN J PLATE
PLATE 70
Angustifolia-macrophylla series, type 14.
Line drawings of morphological details of F 2 of type 14. The garden number
was 11F 2 H 2 P 3 P. )S . The leaf was classified as sessilifolia, although strictly it is
intermediate between sessilifolia and lanceolate. Leaves X %; flowers and
capsules natural size.
The F 3 progeny of this plant consisted of 24 plants of the same sessilifolia
type and 1 "filler," which had leaves more like auriculata of type 8.
[564]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN •] PLATE 76
PLATE 77
Angustifolia-tnacrophyUa series, type 15.
Line drawings of morphological details of F 2 of type 15. The garden number
was lir 2 H 2 P 3 P 10 . The leaf is of the scssilifolia type. Leaves X %; flowers and
capsules natural size.
The F 8 progeny of this plant was uniformly of the same leaf type.
[566]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ S ETCH E LL-GOODSPEE D-CLAU SE N ] PLATE 77
PLATE 78
Angustifolia-macrophylla scries, type 16.
Line drawings of morphological details of F 2 of type 16. The garden number
was 11F 2 H 2 P 3 P S0 . The leaf is of the sessilifolia type. Leaves X %; flowers and
capsules natural size.
The F 3 progeny of this plant consisted of 15 sessilifolia and 8 auriculata.
[568]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCH E LL-GOODS PE E D-C LAUSE N 1 PLATE 78
PLATE 79
Nicotiana Tabacum var. calyctna, U. C. B. G. 110/05.
Line drawings of morphological details of leaf and flower of calycina. The
leaf is of the lanceolata type, and the flowers are of the conspicuously teratolog-
ical, split hose-in-hose form. Leaves X %; flowers and capsules natural size.
L570]
UNIV. CALIF. PUBL. BOT. VOL. 5 [ SETCHELL-GOODSPEED-CLAUSEN ] PLATE 79
PLATE 80
Nicotiana Tabacum var. virgmica, U. C. B. G. 78/05.
Line drawings of morphological details of leaf and flower of virginica. Con-
trast the normal flowers and auricled leaves with the corresponding details of
calyeina, shown in plate 79. Leaves X % ; flowers and capsules natural size.
[572]
UNIV. CALIF, PUBL. BOT. VOL. 5 [ S ETCH E LL-GOODSPEE D-CLAU SE N ] PLATE 80
PLATE 81
Calycina-virginica series, an F, plant.
Line drawings of morphological details of an Fj plant of the calycina-virginica
series. Note the normal flowers and the slightly auricled leaves. Leaves X %;
flowers and capsule natural size.
[574]
UNIV. CALIF, PUBL. BOT. VOL. 5 [ S ETCH ELL-GOODSPEE D-CLAU SE N ] PLATE 81
PLATE 82
Nicotiana Tabacum var. alba, U. C. B. G. 30/06.
Line drawings of morphological details of flower and leaf of alba. Note
especially the rugose leaf. Compare this drawing with those of macrophylhi
shown in plates 57 and 58, figure 2. Leaves X % ; flowers and capsule natural
size.
[576]
UNIV. CALIF. PUBL. BOX. VOL. 5 [ S ETCH E LL-GOODSPE ED-C LAU S E N ] PLATE 82
PLATE 83
Tig. 1. Calycina-virginica series, an F, plant. A typical F, plant of the
calycinct-mrginica series. This plant is at the height of its blooming period. The
garden number was 10F,H 18 P M .
Fig. 2. Alba-macrophylla series, an F, plant. Photograph of a typical F,
plant of the alba-macrophylla series. The garden number was 10F,H 2 ,P r>1 . The
plant is at the height of its blooming period.
[o78j
PLATE 84
Alba-macrophylla series, I\ leaves.
Fig. 1. Photograph of typical leaves of alba.
Fig. 2. Photograph of a typical leaf- of lOF^^Pu, F, of the alba-marcopliylla
series.
Fig. 3. Photograph of a typical leaf of lOF^^P^, F t of the alba-macrophylla
series.
Compare these leaves with those of macrophylla, shown in plate 58, figure 2.
The rugoseness of alba has been carried over, to a somewhat reduced extent, into
the F, hybrid.
[580]
PLATE 85
Fig. 1. Alba-macrophyUa series, F 2 plants. Photograph of two adjacent
plants, IIFoELjPjjP^ and 11F;,H 24 P M P =:1 , from the same F 2 population of the alba-
macrophyUa series. An illustration of segregation for height in this population.
Fig. 2. Alba-macrophyUa series, an F t plant. Photograph of a typical F,
plant, 13F 4 H 24 P 34 P 23 P 2 P-„, of a dwarf line of the alba-macroph ylla series. The
line here illustrated was derived from the dwarf F 2 plant shown in figure 1. This
line has bred true for seven generations.
[582]
UNIVERSITY OF CALIFORNIA PUBLICATIONS — (Continued)
VOL 6. 1914-1919.
1. Parasitic Florideae, by William Albert Setchell. Pp. 1-34, plates 1-6.
April, 1914 „ ; .35
2. Phytomorula regularis, a Symmetrical Protophyte Related to 'Coelastrum, by
Charles Atwood Kofoid. Pp. 35-40, plate 7. April, 1914 05
3. Variation in Oenothera ovata, by Katherine Layne Brandegee. Pp. 41-50,
plates 8-9. June, 1914 10
4. Plantae Mexicanae Purpusianae. VL by Townshend Stith Brandegee. Pp.
51-77. July, 1914 .25
5. The Scinaia Assemblage, by William Albert Setchell. Pp. 79-152, plates
10-16. October, 1914 _ 75
6. Notes on Pacific Coast Algae. I, PylaieTla Tostelsiac. n. sp., a New Type in
the Genus Pylaiella, by Carl Skottsberg. Pp. 153-164, Diates 17-19. May,
1915 „ _ .... .15
7. New and Noteworthy Califomian Plants. IL by Harvey Monroe Hall. Pp.
165-176, plate 20. October, 1915 „ _ „ 15
8. Plantae Mexicanae Purpusianae. VII, by Townshend Stith Brandegee. Pp.
177-197. October, 1915 _ 25
9. Floral Relations among the Galapagos Islands, by A. L. Kroeber. Pp,
199^220. March, 1916 20
10. The Comparative Histology of Certain Califorjiian Boletaceae, by Harry S.
Yates. Pp. 221-274, plates 21-25. February, 1916 ." 50
11. A Revision of the Tuberales of California, by Helen Margaret Gilkey. Pp.
275-356, plates 26-30. March, 1916 , 80
12. Species Novae vel Minus Cognitae, by T. S. Brandegee. Pp. 357-361. May,
1916 :. , 05
13. Plantae Mexicanae Purpusianae. VIII, by Townshend Stith Brandegee.
Pp. 263-375. March, 1917 _ 15
14. New Pacific Coast Marine Algae. I, by Nathaniel Lyon Gardner. Pp. 377-
416, plates 31-35. June, 1917 .40
15. An Account of the Mode of Foliar Abscission in Citrus, by Robert W,
Hodgson. Pp. 417-428, 3 text figures. February, 1918 ' 10
16. New Pacific Coast Marine Algae. II, by Nathaniel Lyon Gardner. Pp. 429-
454, plates 36-37. July, 1918 25
17. New Pacific Coast Marine Algae. HI, by Nathaniel Lyon Gardner. Pp.
455-486, plates 38-41. December, 1918 35
18. New Pacific Coast Marine Algae. IV, by Nathaniel Lyon Gardner. Pp.
487-496, plate 42. January, 1919 15
19. Plantae Mexicanae Purpusianae. IX, by Townshend Stith Brandegee. Pp.
497-504. November, 1919 „ 05
Index in preparation.
VoL 7. 1916-.
1. Notes on the Califomian Species of Trillium L. I, A Report of the General
Results of Field and Garden Studies, 1911-1916, by Thomas Harper Good-
speed and Robert Percy Brandt. Pp. 1-24, plates 1-4. October, 1916 .25
2. Notes on the Califomian Species of Trillium L. IL The Nature and Occur-
rence of Undeveloped Flowers, by Thomas Harper Goodspeed and Robert
Percy Brandt. Pp. 25-38, plates 5-6. October, 1916 ... .15
3. Notes on the Califomian Species of Trillium L. Til, Seasonal Changes in
Trillium Species with Special Reference to the Reproductive Tissues, by
Robert Percy Brandt. Pp. 39-68, plates 7-10. December, 1916 „. .30
4. Notes on the Califomian Species of Trillium L. IV, Teratological Varia-
tions of Trillium sessile var. giganteum H. & A., by Thomas Harper Good-
speed. Pp. 69-100, plates 11-17. January, 1917 - ~ .30
UNIVERSITY OF ILLINOIS-URBANA
3 0112 118457982
UNIVERSITY OF CALIFORNIA PUBLICATIONS — (Continued)
5. A Preliminary List of the Uredinales of California, by Walter C. Blasdale.
Pp. 101-157. August, 1919 JO
6, 7, 8. A Rubber Plant Survey of Western North America. I. Chrysothamnus
nauseosus and Its Varieties, by Harvey Monroe Hall. II. ChrysiL a New
Bubber from Chrysothamnus nauseosus, by Harvey Monroe Hall and
Thomas Harper Goodspeod. III. The Occurrence of Rubber in Certain
West American Shrubs, by Harvey Monroe Hall and Thomas Harper
Ooodspeed. Pp. 159-278, plates 18-20, 8 figures in text. November, 1919. 1.26
9. Phycological Contributions. I, by William Albert Setchell and Nathaniel
Lyon Gardner. Pp. 279-324, plates 21-81. April, 1920 50
10. Plantae Mexican ae Purpusianae. X, by Townshend Stith Brandegee. Pp.
325-331. December, 1920 ... _ J.0
VoL 8. 1919-.
1. The Marine Algae of the Pacific Coast of North America. Part L
Myxophyceae, by William Albert Setchell and Nathaniel Lyon Gardner.
Pp. 1-138, plates 1-8. November, 1919 - _ 81.50
2. The Marine Algae of the Pacific Coast of North America. Part II.
CMorophyceae, by William Albert Setchell and Nathaniel Lyon Gardner.
Pp. 139-374, plates 9-33. July, 1920 „ 2.75
VoL 9. A Report upon the Boreal Flora of the Sierra Nevada of California, by Frank
Jason Smiley. Pp. 1-423, plates 1-7. October, 1921 _ 5.00
VoL 10. 1922-.
1. The Genus Fucus on the Pacific Coast of North America, by Nathaniel Lyon
Gardner „ (Jn press)