FORESTRY
SD
383
02
E57
Engelmann
Oaks of t
GTA CUMSPICE
UNIVERSITY OF MICHIGAN
LIBRARY
ԱՍԼԱԱԱԱԱԱԱԱ
1817
ARTES
SCIENTIA
VERITAS
OF THE
ننننييلي
Ettuatoria
TIETOR
MAZ
MTX
HITINI
FORESTRY LIBRARY
IHINTAMANIIIC
Wanaume
A
Post
SD )
3
THE OAKS
02.
57
8
OF THE UNITED STATES,
By DR. GEORGE ENGELMANN.
.
.
From the Transactions of the Academy of Science of St. Louis, Vol. III., No. 3.
Read March 20, 1876.
ki
ST. LOUIS, MO.
,
2
---
THE R. P. STUDLEY CO., PRINTERS, 221 N. MAIN ST.
2/1835
1876.
K
!
Fruker
uda
!
:
نے 7 /
1
THE OAKS OF THE UNITED STATES.
:
!
By Dr. GEORGE ENGELMANN.
4
1
We have quite a large number of oaks in the United States,
which for more than a hundred years have attracted the attention
of botanists, and we thought we knew them pretty well, i.e. we
thought we could distinguish, limit, and group the species. That
may have been so, to a great extent, in the old States ; but when
the Rocky Mountains came to be explored, and the regions west
of them, new forms were discovered, and often on single speci-
mens, and not rarely on imperfect ones, species were founded and
incompletely described, so that now a straight, clear path through
in such intricacies is difficult to find.
X
A striking example of the deceptive polymorphism of these
western oaks is furnished by the common Rocky Mountain scrub-
oak. This interesting species grows on the foot-hills of the east-
ern slope of the mountains of Colorado, sparingly near Denver,
scarcely north of that city, but abundantly southward, about the
Pike's Peak region, and thence extends through New Mexico
eastward into Texas and westward through Utah and Arizona
into Southern California. The centre of distribution perhaps, at
all events the classical locality of this species, are the mountains
above Cañon City in Southern Colorado.
In the valley and on the mountain slopes about this place the oak
thickets abound, 6-8 ft. high, single trees occasionally 4 or 6 inches
thick and rising up to 12 or 15 feet, rarely higher. The leaves
are 3-4 inches long, broadly obovate, deeply lobed, sometimes
pinnatifid, underneath stellate-pubescent; the broad lobes obtuse
1
1
IN
ܕܙ ܙܕܙܙ
':
2
ENGELMANN-OAKS OF THE UNITED STATES.
[373
or retuse, often again 2-3-lobed. They bear middle sized or small
oval acorns in more or less knobby hemispherical cups. Scattered
copses of these broad-leaved oaks, often of a beautiful brownish-
purple in September, accompany us to within a few hundred
yards of the top of the cañon, but here the character of these shrubs
changes : the bushes are lower, the leaves smaller and in outline
narrower, the lobes narrower and mostly undivided, but still ob-
tuse. Now we near the precipice itself; from the ragged, dizzy
edge we here and there get a glimpse of the young Arkansas,
whose clear green waters toss and foam, twelve or fifteen hundred
feet under us, through the inaccessible gorge, rushing towards the
plains. The oak bushes accompany us even here, but now they
are only 4-6 feet high, with leaves 2 inches long, ovate-lanceolate
in outline, no longer lobed, but coarsely dentate, the acute teeth
terminating in a sharp point; the acorns are scarcely different
from those noticed before. A few steps more and we have
reached the brink of the precipice itself: oak bushes here too,
but only 3 or 4 feet high, with small (1 inch long), oval, firm,
almost cartilaginous, semipersistent, spiny-toothed leaves, here
and there with only very few teeth or quite entire; the acorns
proportionately smaller, of the same short oval shape, or often
elongated from an unusually small, scarcely knobby, and some-
times peduncled cup.
We feel satisfied that we might have abundant material to
characterize several distinct species, certainly 4 or 5 well marked
forms, and, indeed, they have been considered such. The first is
Nuttall's Quercus Gambelii (2. stellata, var. Utahensis, D. C.
Prod.); the second is 2. alba, var. Gunnisoni of Torrey; the
third, with acutish lobes or coarse teeth, is Torrey's old 2. un-
dulata of Long's Expedition, the first oak obtained from these
mountains, and described about fifty years ago; the fourth, from
the edge of the precipice itself, is what has often been mistaken
for Torrey's Q. Emoryi, or what has been named 2. pungens,
Liebm., in part; with it occur entire-leaved forms which seem
to unite with this as a fifth form the Q. oblongifolia, of the same
author, and Q. grisea, Liebm. As a large and broad-leaved
southeastern form somewhat allied to 2. Gambelii I consider
2. Drummondii, Liebm. In herbarium specimens they all
appear distinct enough, but, looking around us, the very abun-
374]
3
ENGELMANN-OAKS OF THE UNITED STATES.
dance of material must shake our confidence in our discrimina-
tion: within the compass of a few hundred yards we find not
only the forms above distinguished, but numbers of others which
are neither the one nor the other, but which are intermediate
between them and clearly unite them all as forms of one single
extremely polymorphous species.
If one oak behaves thus, why not others? Thrown into a sea
of doubt, what can guide us to a correct knowledge ?
Though oaks are so common and such well-studied plants, I
venture in the following pages to repeat old observations in order
to combine with them some which I think are new, and which
will help to throw a little more light on the subject.
The TRUNK—its BARK as well as its woon—is what we first
contemplate, and this at once takes us to one of the principal
points I wish to discuss.
That the trunk is that of a large, sometimes one of the largest,
or of a middle-sized tree, or occasionally that of a shrub, even a
very low one, is well known. On the Atlantic slope of the con-
tinent most species of oaks make trees and only a few are known
as shrubs ; I can now recall not more than one species, the live-
oak of the south, which occurs in both forms: usually an im-
mense tree, it occasionally bears a rich harvest of fruit as one of
the smallest bushes. But it is different on the Pacific slope ;
there we find many oaks as trees in the lower countries, and as
shrubs, usually with smaller foliage and smaller fruit, in the moun-
tains. The lesser number of oaks seem to occur solely in one or
in the other of these forms.
Examining the bark, we at once become aware of the fact
that the popular distinction of "White-oaks” and “Black-oaks” is
based on correct observation. The paler, ashy-gray bark of the
former and the darker, often nearly black, color of the latter cor-
responds, as will be shown, with other essential characters, and
well marks the two principal groups of our American Oaks. The
bark of the White-oaks is inclined to be scaly or flaky, that of the
Black-oaks is usually rougher and deeply cracked and furrowed.
The wood of the White-oaks is tougher, heavier, and more com-
pact-the only wood which is fit to be used by the wheelwright
or cooper, and is for their purposes unsurpassed. The wood of
4
ENGELMANN-OAKS OF THE UNITED STATES.
[375
the Black-oaks is brittle and porous, makes poorer firewood, and,
made into barrels, holds only dry substances. Undoubtedly the
microscopical investigation of both classes of oak-wood will sci-
entifically establish and confirm these distinctions.
While many other trees, such as Pines, Walnuts, Hickories,
Gleditschia, etc., grow rapidly in the first decades of their life,
and make narrower and narrower annual rings as they grow old-
er, the oaks either hold their own, the annual rings being as wide
in age as they are in youth, or they grow more rapidly after the
first 50 or 100, or even 150 years of their existence.
The winter-buds, especially the terminal ones, show some cha-
racteristic differences; they are larger or smaller, acute or obtuse,
smoothish or hairy or tomentose; Quercus Garryana can be
readily distinguished from all the allied Californian oaks by its
large, pointed, tomentose winter-buds.
In the LEAVES, so extremely variable in form, certain types are
generally recognized. It is not here the place to expatiate on
these well-known topics; but I may be allowed the observation,
that those oaks, which in the perfect state have deeply-lobed or
pinnatifid leaves, show in young shoots or on adventitious branch-
lets less divided or only dentate, sinuate, or even entire leaves
(e.g. 2. alba, stellata, falcata, coccinea, palustris, etc.), while,
singularly enough, the oaks whose leaves in the adult tree are
entire or nearly so, often have on the young shoots dentate or
lobed leaves. I need for examples only refer to 2. aquatica, 2.
Phellos, and 2. virens; and even 2. nigra belongs here.
The vernation of the oak leaves has sometimes been mentioned
as conduplicate, meaning that the upper sides of both halves of the
nascent leaf are applied together, and this really is the case with
most oaks which I have been able to examine in this early stage.
We find it both in White and Black-oaks-almost always, I be-
lieve, in those with broad and deeply-lobed leaves; I mention
only 2. alba, macrocarpa and Garryana, Q. coccinea and pa-
lustris, and also the forms allied to 2. Prinus, even those with
narrower, dentate leaves. In the more deeply-lobed, broad-leaved
Black-oaks the two halves of the leaf are, besides, plicate parallel
with the principal nerves.
Next to these range the oaks with the young leaves concave
and imbricately covering one another. Such we find in 2. stel-
دورود
1
pere
376]
5
ENGELMANN--OAKS OF THE UNITED STATES.
::
lata of the first, and 2. nigra of the second group, both with
densely tomentose, thick, young leaves. In other oaks, mostly
such as have broader and more or less entire leaves, the young
leaves imbricatively cover one another like those last mentioned,
but are convex on the upper side, with the edges turned down or
back. Such is the case in Q. cinerea, myrtifolia, agrifolia,
aquatica, chrysolepis, and, I believe, also in 2. undulata, and
in 2. Wislizeni; I find the same to be the case in the deeply
lobed 2. falcata.
The narrow-leaved oaks of both sections have revolute young
leaves, the halves being spirally rolled backwards towards the
midrib, so that only the upper side of the leaf is exposed; the
point of the young leaf is somewhat spreading so that the branch-
let has a squarrose appearance, while in those with imbricative
vernation it is compact. I find the revolute leaf in 2. virens,
pumila, Phellos, heterophylla, and imbricaria. In 2. Catesbæi
I observe an indexed vernation, the long bristle-pointed lobes of
the nascent leaf being curved down over the still younger one.
I believe that the characters of vernation will not only help to
distinguish allied species or doubtful varieties, but will also assist
in unravelling the intricate questions of hybridity.
The young leaves of almost every oak are coated with a dense
stellate down, which in some ( Q. alba, rubra, etc.) is early de-
ciduous, or it disappears later, or is entirely persistent. Besides
these stellate one-celled hairs, several species, those with a clam-
my feeling of the young leaf, have another kind of hair, single or
a few stellately connected, consisting of several cells, obtuse or
clavate, sometimes branched, and often colored, apparently glan-
dular. I notice these articulate hairs, among the White-oaks, in
Q. stellata, and less conspicuously in 2. macrocarpa; among
the Black-oaks, in Q. nigra, myrtifolia, cinerea, falcata,
aquatica, and laurifolia ; in 2. chrysolepis the characteristic
golden scales” are no scales, but consist entirely of such articu-
lated yellow hair, and the young 2. Catesbæi has the same rusty
coating
The venation and more or less distinct reticulation of the
leaves also present characters not to be neglected ; by them, e.g.
two easily confounded Californian oaks, 2. agrifolia and Wisli-
zeni can readily be distinguished even in sterile branchlets.
.
66
+
.
6
ENGELMANN-OAKS OF THE UNITED STATES.
[377
1
The persistence of the leaves is a good character in some spe-
cies, while in others it is unreliable; 2. pumila and laurifolia
on the eastern and 2. agrifolia on the western coast sometimes
retain their leaves until the new ones are fully developed, and
other specimens, even in the same neighborhood, lose them be-
fore the buds swell; some have deciduous leaves northward and
partly persistent ones southward. The broad-leaved forms of
2. undulata are decidedly deciduous, while those with small,
coriaceous, spiny-toothed leaves retain them through part of the
winter, or,
towards their southwestern limit, even into summer.
Only such oaks ought to be called evergreen which retain the
greater part of their old leaves at least until the new ones are fully
grown; the leaves of some oaks persist even into the third
year.
The MALE FLOWERS are important for the diagnosis of some
species, and to some extent even for the grouping of them. I
pass by the form and pubescence of the bracts and of the calyx
lobes as well as the pubescence of the anthers (among all our oaks
only observed in 2. stellata and virens); even the sometimes
present cusp or point of the anthers seems to be of lesser value,
because variable in some species. Of greater importance is the
size and the number of the anthers. The smaller and more
numerous (usually from 5 to 8 or even 10, rarely only 4) occur
in the White-oaks, while in the Black-oaks the anthers are
usually larger and fewer, as a rule only 4, in some species as
many as 5 or 6; only in 2. agrifolia, which also shows other
abnormal characters, 6-8 stamens are the rule, and sometimes 10
are found. The pollen-grains of both groups have a diameter of
about 0.03-0.04 mm.
In numerous flowers of a certain tree of Q. nigra I have seen
abortive pistils with prominent filiform styles--singularly enough
always 2, where we might have expected 3. In flowers of 2.
agrifolia the connective of the anthers was seen to elongate, the
cells to dwindle down and finally to disappear.
The FEMALE FLOWERS furnish valuable characters to distin-
guish the principal groups of our oaks. The pistil consists
normally of 3 carpels and 3 stigmas; not rarely 4 occur, and in
some Californian species (Q. agrifolia and Wislizeni) I have
repeatedly seen as many as 5. The stigmas in our species are
dilated, retuse, or emarginate; in the White-oak group they are
378]
7
ENGELMANN-OAKS OF THE UNITED STATES.
sessile, or rarely (and that sometimes in the same species) borne
on short, more or less erect, styles ; in the Black-oaks we always
find them on longer, patulous, or recurved styles.* As the stig-
mas are measurably persistent, we often recognize this difference
even in the mature fruit.
The FRUIT exhibits the most important characters in the period
of its maturation, first noticed by Michaux, and especially in the
position of the abortive ovules, the beautiful discovery of A. De
Candolle. But before I speak of these I must allude to the
position of the fruit on the branch. It is single or clustered
in the axils of the leaves or their scars, sessile, or more or less
peduncled. In the Black-oaks the peduncle is short or missing,
but in the White-oaks it is sometimes several inches in length;
its presence, however, is of very little specific value, as in many
species either sessile or peduncled acorns are found. In some oaks
this feature is connected, with slight differences in the length of
the petioley or the shape of the leaf; the distinction between the
European 2. Robur and 2. pedunculata is based on such dif-
ferences, and we have an analogous difference in our 2. alba,
where, at least here in the Mississippi Valley, the form with
deeply pinnatifid leaves has usually peduncles as long or little
shorter than the acorn, and the other form with more broadly-
lobed leaves has shorter peduncles or sessile fruit; but sometimes
we find sessile and peduncled fruit on the same tree. Some
White-oaks have always sessile or nearly sessile acorns, as 2.
stellata, while 2. bicolor always bears them on long peduncles.
The acorns mature either in one season or in two, and gener-
ally speaking we find the annual maturation among the White-
oaks and the biennial maturation in the Black-oaks, but the ex-
ceptions to this rule prove that this peculiarity is not necessarily
connected with the essential characters of the two groups. We
have one western White-oak, Q. chrysolepis, with biennial fruit,
and three Black-oaks with annual maturation, 2. pumila of the
east, and Q. agrifolia and 2. hypoleuca of the west.
Thę biennial maturation is easily recognized in the oaks with
deciduous leaves; the tree is never without younger or older fruit,
2
* A group of White-oaks with biennial fructification, peculiar to Southern Europe and
Eastern Asia, the best known representatives of which are 2. Cerris, 2. Pseudo-Suber, and
2. occidentalis, differs from all these by their patulous or recurved styles bearing ligulate,
acutish stigmas.
8
ENGELMANN-OAKS OF THE UNITED STATES.
[379
or, from May to September, with both; the older acorns are then
seen on the older, leafless part of the branchlet, and the young,
incipient ones on the younger, leafy part. In oaks with per-
sistent leaves some difficulty may arise from the peculiarity
that the branchlets which had flowered the previous year, and
are now maturing the fruit, often in the second year do not
elongate or make new leaves or new wood-in short, do not per-
form any function but the maturation of the fruit. In this case
the fruit is found near the end of the branchlet, absolutely as if it
were an annual fruit; but the appearance of the leaves as well
as of the epidermis of the branch proves them to be over a year
old, and wherever a new shoot of the present year can be discov-
ered, the difference between this and those of the last year easily
solves any doubts. In 2. chrysolepis this peculiarity is quite
striking ; very rarely (at least in the herbarium specimens exam-
ined by me) the fruit-bearing branchlets elongate and again bear
flowers, which is the rule in our deciduous biennial oaks.
The
cup of the acorn, an involucral organ, is in all our species
covered with imbricated scales, appendicular organs which simu-
late bud-scales, and even occasionally seem to assume a pseudo-
phyllotactic arrangement. In the Black-oaks these scales are
membranaceous and never thickened at base; in the White-oaks,
on the contrary, they sometimes have herbaceous tips and, at
least the outer and lower ones, are always more or less thick-
ened, inflated, or knobby at base ; they are very thick, e.g. in 2.
alba and lobata, and very slightly thickened in Q. stellata and
Garryana ; in 2. macrocarpa they are herbaceously tipped.
The shell of the nut or acorn is thinner in the White-oaks and
thicker in the Black-oaks; a much more important and striking
character is, that in the former its inside is dark, smooth, and even
shining, or rarely pubescent, and in the latter densely silky-tomen-
tose, a difference which, I believe, is constant.
Only one of the 6 ovules of the oak-ovary is developed, while
the 5 others persist as small but distinctly recognizable oval,
dark colored, pendulous bodies, outside of the seed-coat, in the
White-oaks at the base of the perfect seed, in the Black-oaks
just below its tip. Only in one of our species, Q. chrysolepis,
are they intermediate or lateral, in some acorns almost basal, and
in others scattered over the side froin near the base to two-
380]
9
ENGELMANN-OAKS OF THE UNITED STATES.
i
thirds up
DeCandolle has observed the same in the Cork-oak
of Europe and in some Mexican White-oaks. The Black-oaks
with annual fructification have these ovules always suspended
near the tip of the seed, and are in this respect undistinguishable
from the regularly biennial Black-oaks.
It is well known that in the southeastern Live-oak both cotyle-
dons are united into one mass-a singular but isolated fact which
has no systematic significance.
In the foregoing pages I have purposely left aside the very
peculiar Californian Q. densiflora, which is in every respect dif-
erent from the other oaks, and thus far the sole representative of
a peculiar group named by DeCandolle Androgyne. In many
respects it is more a chestnut than an oak, for it has, just like the
chestnuts, the same dense-flowered, erect male spikes, 10 stamens
to each flower, very small anthers on long filiform filaments, with
very small pollen-grains (0.017 mm. in diam., not much more
than half as large as in other oaks), and in the female ftowers
slender, terete, pointed stigmas, grooved above. In place of the
spiny involucre of the chestnut our plant has a spiny cup, and
is thus made an oak and not a chestnut. The maturation is
biennial. The shell of the nut is thicker and harder than in any
other of our oaks, the inside thickly tomentose, and the abortive
ovules are found near the top of the seed. The wood is brittle
and worthless.
It results from these investigations that our oaks, leaving again
aside the one last mentioned, arrange themselves into two great
groups, often alluded to above as the White-oaks and the Black-
oaks.
The White-oaks are characterized by paler, often scaly, bark,
tougher and denser wood, and sessile or subsessile stigmas, and
bear the abortive ovules at the base or rarely on the side of the
perfect seed. Besides this, the leaves and their lobes or teeth are
obtuse, never bristle-pointed, though sometimes spinous-tipped ;
their stamens are more numerous, the scales of the cup more or
less knobby at base, the inner surface of the nut glabrous or
(rarely) pubescent; the fruit generally matures in the first year.
The Black-oaks have dark, furrowed bark, brittle and porous
.
IO
ENGELMANN-OAKS OF THE UNITED STATES.
(381
wood, styles long and spreading or recurved, abortive ovules al-
ways near the tip of the perfect seed. The leaves and their lobes
are bristle-pointed, at least in youth ; lobes and teeth acute; teeth
sometimes spinous. Their stamens are usually less numerous, the
scales of their cup membranaceous, the inner surface of their nut
always tomentose; the fruit generally matures in the sccond year:
We may then arrange our oaks in the following order:
QUERCUS, Lin.
I. Lepidobalanus, Endl. : Amenta mascula pendula; pollinis cellulæ
0.03-0.04 mm. latæ; flores feminei a masculis distantes: stigmata dilatata.
A. LEUCOBALANUS: Ovula abortiva infera vel raro lateralia ; stamina
plerumque 6-8; stigmata sessilia vel subsessilia; nux intus glabra s.
rarissime pubescens.
* Maturatio annua; nux intus glabra; ovula abortiva infera.
j Folia decidua.
2. lyrata, 1 macrocarpa,” alba, lobata, stellata, Garryana, bico-
lor, Michauxiï, 3 Prinus, 4 prinoides, Douglasii, undulata, 5
tt Folia sempervirentia.
2. dumosa, 6 Emoryi,? reticulata, 8 virens. 9
** Maturatio biennis; nux intus pubescens; ovula abortiva infera vel latera.
lia; folia sempervirentia.
Q. chrysolepis. 20
B. MELANOBALANUS: Ovula abortiva supera; stamina plerumque
4-6; styli elongati demum recurvi; nux intus sericeo-tomentosa.
* Maturatio annua; folia persistentia s, subpersistentia.
2. agrifolia, 11 hypoleuca, 12 pumila 13
** Maturatio biennis,
† Folia decidua.
2. palustris, rubra, Sonomensis, coccinea, 14 ilicifolia, Georgia-
na, Catesbæi, falcata, nigra, cinerea,15 aquatica, laurifolia, 16
heterophylla, 17 imbricaria, Phellos.
† † Folia sempervirentia.
Q. Wislizeni, 18 myrtifolia.19
II. Androgyne, A. Dec.: Amenta mascula erecta, basi flores femineos
gerentia; pollinis cellulæ fere 0.017 latæ; stigmata linearia.
2. densiflora.
NOTES.
1. Quercus lyrata, Walt., extends as far north as Taxodium does, to the
banks of the lower Ohio in Illinois.
2. 2. macrocarpa, Michx., is extremely variable in the size of its acorns,
and especially in the depth and the margin of its cup, which sometimes
382]
II
ENGELMANN-OAKS OF THE UNITED STATES.
covers the acorn scareiy one-half, usually three-fourths, and occasionally
entirely; the margin is profusely or sparsely fringed. --Throughout the
north-west, north of the Missouri river, a low scrubby form is found, which
might be designated as var. depressa, as it is undoubtedly the obtusiloba
B. depressa, Nutt. gen. 2, 215, which has smaller leaves and much smaller
acorns than the species, but is clearly a form of macrocarpa.
3. 2. Michauxii, Nutt. gen. 2, 215, excl. syn.—The figure of Michaux,
quoted by Nuttall, refers to 2. bicolor, and none of his figures represent
our plant. Elliott adopts Nuttall's name, but Chapman as well as DeCan-
dolle consider it a form of Prinus. 2. Prinus was described by Linnæus
with foliis obovatis utrinque acuminatis, which sufficiently well agrees
with all the forms of Prinus proper. Our plant is distinguished by having
the leaves obtuse, or mostly cordate, at base; thicker, more leathery, and
tomentose, on the lower side; and the male flowers 10-androus. All the
forms of Prinus proper have a very deciduous pubescence on the lower
side of the leaf, which is acute or acutish at base.
4. 2. Prinus, Lin., would then comprise Michaux's varieties, palustris,
monticola, and acuminata.
5. 2. undulata, Torr., has been treated of in the introduction to this
paper; the different forms, there also enumerated, are — I. Gambelii (2.
Gambeltii, Nutt. and probably 2. Drummondii, Liebm.); B. Gunnisoni
(2. alba, var. Gunnisoni, Torrey); y. Famesii, Torrey's original plant,
figured in Ann Lyc. N.Y. 2, t. 4; the original figure reproduced with slight
alterations in Nuttall's N. Am. Sylv. 1, t. 3; d. Wrightii, often confounded
with 2. Emoryi, and apparently one of the forms comprised by Liebmann
in his 2. pungens. 2. oblongifolia, Torr., and 2. grisea Liebm., seem
to be forms with more or less entire leaves; or the latter may perhaps have
to be referred to the Mexican 2. microphylla.
6. 2. dumosa, Nutt., N. Am. Sylva, 1. p. 7; Torrey, Bot. Mex. Bound.
p. 207. 2. acutidens, Torr. ib. tab. 51, is a larger form of the same. 2.
berberidifolia, Liebm., DeProd. 16, 2, p. 36, seem to belong here either
entirely or at least in part. A shrub of the southern part of California,
often very squarrose, sometimes with slender and erect branches; leaves
oval, obtuse, often cordate or obtuse at base, spinous-dentate or sometimes
entirety, dark green above, hoary tomentose or pubescent below, from 1 to
or sometimes i inch long; fruit sessile; cup strongly tuberculate, black,
between 2 and 6 lines in diameter; acorn large for the size of the plant,
oval, or small and narrow,
7. 2. Emoryi, Torr. Emory Rep. 1848, p. 151, t. 9, 2. hastata, Liebm.
Quite distinct from 2. undulata var. Wrightii, which is often confounded
with it; the peduncled acorn of Torrey's figure Morax belong to that form
of undulata. This pretty Arizonian species was collected by Emory in 1846,
and soon afterwards by Wright, and then not again until Dr. Rothrock,
a year or two ago, brought back fine specimens from Lieut. Whipple's Ex Wheelers
pedition. The leaves are not roundish or oval and pale as in Wrightii,
but lanceolate, cordate at base, and dark green; the acorns in all the
/
I 2
ENGELMANN-OAKS OF THE UNITED STATES.
[383
specimens seen by me are sessile, the bright brown scales of the cup only
slightly thickened at base.
8. 2. reticulata, H. B. K., has been found in Southern Arizona by Dr.
Rothrock, in the expedition just mentioned.
9. 2. virens, Ait. A shrubby form is var. maritima, Chapm, 2. mari-
tima, Willd., from which var. dentata, Chapm., cannot be separated; both
have shorter and often larger acorns on shorter peduncles than the spe-
cies; the former is the larger shrub, rarely as much as 10 feet high, with
usually entire lanceolate leaves; the latter often bears fruit when only 1-1}
feet high; leaves sometimes dentate or sinuate-dentate, 1-2 inches long;
vigorous ground shoots occasionally produce broad oval, entire, or dentate
leaves, 3-4 inches long and 1-2 wide.
10. Q.chrysolepis, Liebm., has so often been spoken of in the foregoing
pages that little need be added. Its fructification was misunderstood until
the abundant material, brought together by Prof. W. H. Brewer for the
California State Survey, permitted me to clear it up. The size of the plant,
of the leaves, and of the fruit, is extremely variable; and even the yellow
pubescence, which has given it its name, is neither persistent. nor is it
present in all cases. Young vigorous shoots or young trees have spiny-
dentate leaves; older trees, especially on fertile branches, usually entire
ones. The acorns are sometimes very large and the shallow cup extremely
thick: this is the form Torrey (Pacif. R.R. Rep. v. 365, tab. 9) has de-
scribed as R. crassipocula ; Dr. Parry sends from San Bernardino still
larger cups, I inches in the outer diameter. Dr. Kellogg's 2. fulrescens,
in Proc. Calif. Ac. I, 67 & 71, seems (from specimens seen in Hb. Brewer)
to refer to the form with middle-sized acorns and cups of the ordinary
shape, without that unusual thickening; his 2. vacciniifolia, ib. I, 96
(106 ed. 2) is a small-leaved mountain form. Of this variety specimens
are found entirely destitute of the yellow, scurfy pubescence even in the
earliest youth. The anthers of this species, usually 10 in number, are
always strongly pointed; the broad stigmas are closely sessile. The late-
ral position of the ovules has been mentioned.
II. 2. agrifolia, Née, the first western oak that became known (1802),
is quoted by the author as inhabiting “Nootka Sound” and California
perhaps by mistake, as now it does not seem to be known much north
of the Bay of San Francisco, and it extends as far south as the southern
boundary of the State, but does not ascend the mountains. It is a fine
large almost evergreen tree, but makes miserable timber and even poor.
firewood. The old leaves partially fall off in winter, so that the heads be-
gin to look less dense towards spring; in some trees the last leaves have
fallen before the young ones are developed, but generally they do not come
off entirely before the young verdure covers the branches. Dr. Bolander
remarks that occasionally odd-looking trees are observed which in spring
retain all their old leaves without bringing forth flowers or young sñoots
a state of things which resembles the condition of 2. chrysolepis, above
alluded to; that species, however, performs the function of maturing its
384]
13
ENGELMANN-OAKS OF THE UNITED STATES.
}
fruit, though it bear no young leaves, while in this case there would be in
spring an almost absolute winter-like stagnation of the vegetation. It has
certainly an annual fructification, but is in every respect, except in the
number of the large stamens (6–8 and often more), a regular Black-oak.
The acorn is always long pointed, whence the name Torrey gave it, 2.
oxyadenia, (Sitgr. Rep. tab. 17), is not inappropriate.
A southern variety of this species is shrubby, with smaller leaves, occa-
sionally pubescent, and with smaller but very abundant fruit. From the
often very simiiar 2. Wislizeni it can, even without fruit, always be distin-
guished by the dull, pale upper surface of the leaves, which is usually con-
vex, and by the absence of reticulation on it.
12. 2. hypoleucu I name an Arizona oak which Torrey, in Mex. Bound.
Rep. p. 207, refers to 2. confertifolia, H. B. K., a species with biennial
fructification and slightly pubescent leaves. Our plant is characterized,
besides its annual acorns, by lanceolate thick leaves with revolute mar-
gins and a white tomentose lower surface. The 5-lobed calyx is scarcely
hairy and bears 4 stamens; no bracts seen even before the flowers open.
13. 2. pumila, Walt. Fl. Carol. p. 234. Michx. Sylv. tab. 17 (where the
fruit is erroneously represented as biennial, otherwise the figure is good).
This interesting shrub. though first described nearly a century ago, has
only, through the efforts of Dr. J. H. Mellichamp, become properly known
in the last few years. Living in the immediate vicinity of its habitat, the
pine barrens of the low country of South Carolina, this acute observer has
aided me in the most liberal manner in studying this as well as other dif-
ficult oaks of that region.
2. pumila is called the Running-oak because by the aid of its wide-
spreading stolons it covers large patches, sometimes acres, with its thick-
It is often, especially where kept down by the frequent fires, only 1-2
feet high, and has been seen loaded with flowers when only of 6 inches;
in other localities it grows 8-10 feet high, with stems i inch in diameter.
The leaves, revolute in vernation, are usually about 2 inches long, lanceo-
late, entire and often undulate, only occasionally dentate-lobed, but in
vigorous shoots sometimes broad ovate and deeply and acutely lobed ;
another form has obovate obtuse leaves. They are slightly pubescent
when young, but soon become quite glabrous, persist through the winter
and occasionally beyond the flowering period. In the male flowers I find
pretty regularly 4 stamens, and in the female 3 long recurved styles. The
globose fruit in its shallow cup is nearly sessile in the axils of the same
year's leaves.-- 2. pumila, Walt., Michx. Sylv., Nutt. gen., Elliott Flor.;
2. Phellos var. pumila, Mich. Querc. & Flor.; 2. cinerea var. pumila,
Chapm., A. DeCand. Prod.
Var. sericea has similar narrow, or larger, ovate-lanceolate leaves, al-
ways silky-white underneath; the larger leaves on fertile branches grow
over 4 inches long by If inches in width, and on sterile shoots even larger.
-2. sericea, Willd., Pursh.; 2. Phellos var. sericea, Ait.
1
ets.
14
ENGELMANN-OAKS OF THE UNITED STATES.
[385
The leaves of the glabrous form resemble those of Phellos and of the
silky variety those of cinerea, and without the fruit they could not well be
distinguished from some forms of them.
14. 2. coccinea, Wang. I have, with some hesitation, followed DeCan-
dolle and Gray in uniting with this species 2. tinctoria, Bart., which
has broader, less lobed and firmer leaves, and a deep yellow colored inner
bark; but I suspect that specific differences may yet be discovered.
15. 2. cinerea, Michx. In specimens from S. Carolina I find, together
with the ordinary stellate pubescence, an abundance of yellow articulated
hair on the young leaves, while in flowering Texan specimens it seems to
be entirely wanting:
16. 2. laurifolia, Michx , appears after all to be distinct from Q. aqua-
tica ; whether entire or lobed, the leaves of the latter have a cuneate out-
line widest in the upper third or at least above the middle; the calyx lobes
are larger and very conspicuous, and the filaments enclosed and only the
anthers exsert. 2. laurifolia has lanceolate oblong leaves, widest about
the middle whether entire or lobed; the calyx lobes are much smaller;
the filamentsd $344.fexsert; this in flowering specimens of both species from
Bluffton, the only ones which I could compare. A specimen from the
gulf coast of Mississippi has oval entire coriaceous leaves 4 inches long
and 15 inches wide, while those of my South Carolina plants are narrower,
and rather approach to Phellos, but never to aquatica. They usually per-
sist until the budding time, but not beyond it; therefore I would not
call them really evergreen.
17. 2. heterophylla, Michx., must, I believe, like the foregoing, be re-
adopted as a distinct species, as it is neither a variety of aquatica or Phel-
los, nor a hybrid of any of these oaks. As I have not yet seen flower or
fruit, my opinion, which stands alone in opposition to the best recent
botanists, must for the present be taken for what it may be worth.
I distinguish Michaux's species by its long and distinctly petioled leaves,
which in vernation are revolute, and are glabrous from their earliest age.
My specimens, natives from New Jersey, cultivated ones from Bartram's
and Marshall's gardens, and from the European gardens at Verrière.
Herrnhausen and Prague, the latter fertile, agree in this respect among
themselves and with Michaux's figure in his Sylva. In all these specimens
the leaves are lanceolate, entire, or sinuate-dentate, 3 or mostly 4-6 inches
long, 1-2 inches wide, on a petiole 3-9 lines long. In the allied species,
Phellos, laurifolia, and aquatica, the petioles are usually inconspicuous
or merely 1-2 lines long; only 2. imbricaria, which is also readily dis-
tinguished by its pubescence, has plainly petioled leaves. I suspect that
some specimens claimed for Phellos are entire leaved forms of the spe-
cies in question. May these suggestions induce the local botanists of the
lower Delaware region, the favorite home of this oak, to work up the
species.
18. 2. Wislizeni, A. DC. With his usual acumen, A. DeCandolle dis-
covered this species in a small fruiting specimen, brought by Dr. Wislize-
386]
15
ENGELMANN-OAKS OF THE UNITED STATES.
nus in 1851 from the American Fork of the Sacramento River, but, through
a mistake of inine, he located it near Chihuahua. Since then nothing fur-
ther, I believe, has been published about this remarkable oak, though an
abundance of material and very full notes have been gathered by different
collectors, principally by Prof. W. H. Brewer and Dr. H. Bolander.
This species is found throughout the western parts of California from
Shasta to San Diego, principally in the region of the foot-hills, but does
not ascend the higher mountains. In some localities it makes a “magnifi-
cent tree” 40 to 60 feet high, with a trunk occasionally 6 feet in diameter,
but branching 5 or 6 feet from the ground, as most of the large Californian
oaks of both groups are wont to do. On the coast ranges from Monte Dia-
blo to San Diego it also occurs as a small shrub with small leaves.
The bark is pale and smoothish in younger, very rough and black in
older trees. The firm, leathery leaves persist 14 or 15 months on the
branches; they vary excessively, often on the same tree, from broad ovate
to narrowly lanceolate; cordate, obtuse, or acute, at base; the margin
entire, or with a few teeth or sharply and closely dentate; shoots or young
trees have usually dentate, old and fertile ones more commonly entire
leaves. In the earliest age the leaves are very slightly concave, and in
vernation imbricate; they bear on both sides articulated hair, but soon
become glabrous; the full grown leaves are mostly dark green and shin-
ing, and delicately reticulate, principally on the upper surface. They are
usually 2-4 inches long and half as wide, or rarely narrower; petioles
5-9 lines long; in var. fruticosa the leaves are only 1-14 inches long,
oval, entire, or often very sharply and deeply lobed-dentate; petioles 1-2
lines long.
The rhachis of the aments is stellate-canescent, or nearly glabrous;
calyx-lobes 5 or 6, large and broad, nearly glabrous or ciliate-bearded;
anthers 3-6, often pointed. Bracts of the sessile (or often peduncled) female
flowers large, orbicular, membranaceous; the long, recurved styles not
rarely 4 or 5 in number. Acorns always elongated, 9-18 lines long, im-
mersed } to ; in the cup, which I find varying from 6-11 lines in depth
and 5-6 lines in width; cup-scales elongated acutish, light brown, and
nearly glabrous.
On one hand this species approaches to 2. agrifolia, and on the other
to 2. Sonomensis.
Dr. Kellogg, in Proc. Cal. Ac. 2, 36 (DC. Prod. 16, 2, 79), scantily de-
scribes an oak under the name of. 2. Morehus, which I have no means of
identifying; possibly it may belong here.
19. 2. myrtifolia, Willd.
Willdenow's description of the foliage,
which cannot possibly refer to any other oak, together with his locality,
makes it certain that in Dr. Mellichamp's very complete specimens we
have his plant before us, and, thanks to him, I can now reëstablish this
little known and often doubted species. It grows on the poorest sand
ridges near Bluffton, together with Pinus australis, very rare there,
but apparently extending along the coast to Florida. It makes an ever-
m.
+------------
16
ENGELMANN-OAKS OF THE UNITED STATES.
[387
green shrub from 10-2, usually 4-5, and up to 8 feet high. Leaves
rounded ovate, cordate, obtuse, or sometimes acute at base, obtuse and in
youth bristle-pointed at tip, revolute on the margin, thick and leathery,
persisting 15-18 months. Leaves vary sometimes to broadly obovate, or
are rarely, in young shoots, sinuate-angled; they are usually 1-15 or even
2 inches long, but in vigorous ground shoots have been found 2 and 3
inches in length by 2 in width. The young leaves are densely covered
with a rusty, clammy scurf of articulated hair, which after a month or so
disappears, leaving a glossy surface. Vernation imbricate; youngest leaves
flat with recurved margins. Aments about if inches long with stellate-
canescent rhachis, 5 oval pubescent calyx lobes, and a few (mostly only
2-3) small cuspidate anthers. Fruit sessile or usually short peduncled,
single or in twos; cup very shallow, about 6 lines wide, with ovate-trian-
gular obtuse scales; giand ovate or subglobose, 5 or 6 lines long, covered
by the cup for for of its length.-- 2. myrtifolia, Willd., Nuttall, Pursh,
Elliott, only the first two of which seem to have seen sterile specimens;
2. Phellos var, arenaria, Chapm. ; 2. aquatica var. myrtifolia, A. DC.
HYBRID OAKS.
The question of hybridity in plants is in every case difficult to
solve where its usual character, the sterility of the hybrid, fails
us, and where we have nothing to rely on but the rarity and indi-
viduality of a form that seems to stand intermediate between two
well established species which occur in its neighborhood, and
which could be considered its parents.
This is just the case in oaks. All the supposed hybrids are
abundantly fertile, and those of their acorns which liave been
tested have well germinated; in fact, as far as I know, no differ-
ence in fertility or germinating power between them and the
acknowledged species has been discovered. The seedlings of
such questionable individuals do not seem to revert to a supposed
parent, a sport of which they might be claimed to be, but propa-
gate the individual peculiarities of the parent; “ come true," as
the nurserymen express it. At the same time, it is a remarkable
fact, that, notwithstanding their fertility, they do not seem to pro-
pagate in their native woods; we may properly ascribe this to a
lesser degree of vitality in the hybrid progeny, which causes them
to be crowded out in the struggle for existence : one of the pro-
visions of nature to keep the species distinct.
White-oaks and Black-oaks are too distinct to hybridize with
one another. Thus far no hybrids have been discovered among
388]
17
ENGELMANN-OAKS OF THE UNITED STATES.
the former, while among the Black-oaks I find six forms, enumer-
ated below, which I consider as real hybrids; of them only a few,
usually only single individuals, have become known; their exist-
ence cannot well, without straining facts, be considered due to
innate variability in a supposed parent. Four of these hybrids
have been found in the Mississippi Valley and two in South Caro-
lina. When more carefully looked for, undoubtedly more will be
discovered. The four western hybrids all claim 2. imbricaria
as one of the parents, while the two southeastern ones seem to
point to l. cinerea; both are species with entire leaves, and the
mixture of such with lobe-leaved forms would of course be more
readily discovered from the intermediate leaf-form of the illegiti-
mate offspring; but it remains for further close examination to
ascertain whether lobe-leaved species do not hybridize among
themselves, or entire leaved-forms also mix together, producing
offspring of less strikingly marked characteristics.
That we have to look for one of the parents of all our hybrids
to only two species, seems to correspond well with other observa-
tions, all pointing to the fact that some species of a genus are
more prone to hybridize than others. This is true of Verbenas,
hybrids of which abound in this neighborhood in numerous forms
as well as in a great many individuals; of most of them V. stricta
appears to be one of the parents, perhaps because one of the most
common species, or from some innate quality which makes it
mix more readily with others; perhaps from a peculiar structure
of the fower which may promote insect agency. Our hybrid
Verbenas differ from the hybrid oaks in bearing scarcely any fer-
tile seeds, while at the same time they are so common that evi-
dently they are readily produced anew.
Our oak-hybrids are the following:
Probable Parents.
Name under which described.
2. coccinea, 2. imbricaria,
2. Leana.
2. rubra,
2. palustris,
Q. nigra,
2. tridentata.
Q. Catesbæi, 2. cinerea,
2. sinuata.
2. falcata,
1. 2. imbricario-coccinea was first described and figured by Nuttall,
about thirty years ago, under the name of 2. Leana, Nutt. Sylv. Contin.
1, tab. 5 bis; DC. l. c. 62. The original type was discovered by Mr. T. G.
66
:
2
18
ENGELMANN-OAKS OF THE UNITED STATES.
[389
Lea, near Cincinnati, and soon afterwards Dr. S. B. Mead found another
tree in Hancock Co., Illinois. My specimen, obtained from the first dis-
coverer, has entire or sinuate or dentate or dentate-lobed leaves, 4-6
inches long and half as wide, and even in September slightly pubescent
below; lobes acute and bristle-pointed or quite obtuse; base attenuated
into a petiole 5-8 lines long; acorns similar to those of coccinea, cup shal-
lower with obtuse scales. The leaves in Nuttall's figure have a cordate
base. Dr. Mead's tree is similar to Lea's; leaves apparently more com-
monly entire or undulate-sinuate, 5-7 inches long and half as wide, obtus-
ish at base with a petiole i inch long; the pubescence has almost disap-
peared on the lower side of the autumnal leaf; acorns globose, covered
*-} by the canescent cup. Mr. E. L. Greene sends another specimen from
Macon Co., Ills.; it is rather more glabrous but otherwise similar, with-
out fruit.—The relationship to imbricaria is unquestionable, and it is quite
probable that among the lobe-leaved Black-oaks we must look to one of
the forms of coccinea as the other parent.
2. 2. imbricario-rubra. I found this hybrid two years ago in St. Clair
Co., Ills., 20 miles from St. Louis, in low, fertile woods where both rubra
and imbricaria form the bulk of the forest Growth of the tree and bark
like rubra ; leaves ample, 4-8 or 9 inches long, 2-6 inches wide, obtuse or
cordate, rarely acute, at base, the smaller more commonly oblong and en-
tire, the larger ones oval or obovate, entire or sinuate, or with a few broad
and shallow obtuse or triangular bristle-pointed lobes; in June still downy
on the lower surface; petioles 4-1 inch long, pubescent; fruit unknown.
3. 2. palustri-imbricaria was observed by me a few years ago, 8 miles
west of St. Louis, in a little dell where imbricaria abounds; palustris,
coccinea, and nigra, together with some White-oaks, were near by; the
tree was only 8 inches in diameter but in full bearing. It had, unfortu-
nately, to give way to a railroad track; but ripe fruit was obtained, which
to Mr. Meehan of Germantown has furnished fine young plants, completely
agreeing in character with the parent.—Leaves, as far as I could see, not
revolute in vernation, pubescent on both sides, but completely denudated
before the end of May. Full grown leaves broad-lanceolate, mostly acute
at base, entire or more frequently with a few (sometimes more) coarse,
triangular-lanceolate, acute, bristle-pointed teeth, glabrous on both sides;
about 4 inches long, if wide, rarely larger; peduncles 3-4 lines long; cup
moderately deep, turbinate at base, 6–7 lines wide, 3-4 high; ovate-obtuse
scales, canescent, with bright brown margins.
4. 2. imbricario-nigra (2. tridentata, Eng. in Hb.), 2. nigra var.
tridentata, DC. 1. c. 64. A single tree, rather small, which was soon after-
wards destroyed, was found by me, in the autumn of 1849, on the hills 6
miles east of St. Louis, in company with both supposed parents and cocci-
nea and rubra, together with some White-oaks. Foliage as well as fruit
are of such decided character that the origin of this hybrid can scarcely be
doubted; the leaves are rather those of imbricaria, with a touch of the pe-
culiar lobation of nigra, and the fruit is more like that of nigra. Leaves
390]
19
ENGELMANN--OAKS OF THE UNITED STATES.
elliptical to obovate, entire or often coarsely 3-dentate at the apex, occa-
sionally with a few teeth on the sides; 4-7 inches long, 2 or 3 wide;
base rounded or acutish; upper surface dark, shining green, lower one
pale, and in September not quite glabrous; petiole 4-10 lines long. Acorns
closely sessile; the hemispherical, turbinate, canescent cup about half-
enclosing the globose nut.
5. 2. cinereo-Catesbæi; 2. sinuata, Walt. Car. 235, DC. 1. c. 74. It is
quite probable that in the tree observed by Dr. Mellichamp, several
years since, near Bluffton, S. C., and not far from Walters' abode, we
meet with Walters' obscure and long ignored species. Mr. Ravenel has
also observed a similar form in South Carolina, and indicated cinerea as
one of the parents. Dr. M.'s tree grows on a sandy ridge with Catesbæi,
falcata, and virens; cinerea not far off, but rare; it is 40 feet high and
well grown, has a “very dark, deeply cracked bark, which is red inside
like Catesbæi.” Leaves 4, rarely 5-6 inches long, about half as wide,
attenuated at base into a partially margined petiole, 3-6 lines long; leaf
itself oblong to obvate, sometimes almost rhombic; sinuate with shallow
obtuse lobes to divaricately dentate-lobed; lobes obtuse, or acute and bris-
tle-pointed, dark green and shining on upper surface, paler but glabrous
and with some axillary down beneath. In early youth both sides, the lower
more than the upper, are covered with the rusty, articulated pubescence of
Catesbæi, and are as it seems imbricative in vernation. Male flowers with
4 large, pointed anthers. Acorns sessile; cup hemispherical, turbinate,
8-10 lines wide, 5 or 6 high; nut oval, 8-9 lines high and 6-8 thick, or
& covered by the cup.-One of the parents is doubtless 2. Catesbæi, as the
other cinerea, falcata, or perhaps aquatica, present themselves; falcata
would produce very different leaves, aquatica grows in a different soil and
would not probably mix with the “barren oak”; so that cinerea with its
entire leaves remains, though rare there, as the most probable other parent.
6. 2. falcato-cinerea is quite a late discovery of the same successful
explorer, who found it in the vicinity of the last mentioned hybrid. It
still more distinctly shows its parentage.-Leaves oblong, usually obtuse
or cordate at base; often entire or with one or a few teeth, or divaricately
trilobed, some of them exactly resembling forms of falcata var. triloba;
leaves 3-5, usually 4 inches long, 13-2 and the lobed ones over 3 inches
wide; petiole 6-9 lines long. The upper surface of the leaves is not reticu-
lated as in most allied oaks, but almost entirely smooth, like 2. cinerea;
pale green; lower side whitish canescent. Young fruit subsessile; ro ma-
ture acorns seen.
2. coccineo-ilicifolia, Gray, Man. ed. 5, p. 454, found by Dr. Robbins
in Massachusetts, is unknown to me.
Several forms of oaks have at one time or another been consid-
ered as hybrids which most probably are varieties or sports of
of one or the other of the well-established species, or, in one in-
stance, seem to claim the rank of species themselves.
1
i
20
ENGELMANN-OAKS OF THE UNITED STATES.
[391
-.-.--.
2. oliveformis, Michx., is, according to A. Gray, a variety of
macrocarpa. After carefully comparing several specimens refer-
red to olivæformis with numerous forms of macrocarpa, I cannot
but fully coincide with this view. Mr. E. Hall of Menard Co.,
Ills., has a found a tree in his neighborhood which has exactly
the leaves of olivæformis, as figured by Michaux, lobed so deeply
that the midrib is nearly bare, with an ovate fruit larger than that
of Michaux (which was most probably incomplete or abortive),
and about half immersed in the deep, not fringed, strongly knob-
bed cup. This specimen has been claimed as a hybrid of macro-
carpa and alba (Amer. Ent. & Bot. 1870, p. 191). Such leaves,
however, are not very rare in macrocarpa, and I have repeatedly
seen in western forms of macrocarpa exactly the same kind of
acorns, with or without a fringe on the edge of the cup.
2. runcinata was the name given to a form I found in the
richest Mississippi-bottom lands opposite St. Louis, together with
rubra, imbricaria, and palustris. From its smaller and nar-
rower, grossly dentate, not lobed leaves, and its smaller fruit, it
seemed distinct enough from rubra, and was possibly a hybrid
of it and some other small-fruited allied oak. But the leaves of
rubra are so variable in size and outline that most probably
DeCandolle (1.c. 60) is right in considering it a variety of rubra.
Q. quinqueloba I named a form of nigra with 5-lobed leaves,
which I found on the hills of St. Louis ; DeCandolle (1. c. 64)
places it correctly with nigra. It is not even a variety, but ra-
ther a juvenile state which had become permanent in that tree;
young trees or shoots of nigra have sinuate-dentate or many-
lobed leaves, but in fertile ones the leaves are almost always
more or less 3-lobed or 3-dentate. I have since seen a tree which
on one fruit-bearing branch had only the leaves of quinqueloba,
while all the other branches had the regular cuneate 3-dentate
nigra leaves.
2. heterophylla, Michx., has by some been considered a hy-
brid of some species with entire, narrow leaves, and a lobed one ;
DeCandolle takes it for a form of aquatica, and Gray partly for
that, partly for a form of Phellos. I have above expressed my
opinion that it is a good species, not to be confounded with the
lobe-leaved forms of either.
DATE DUE
APA 10 1979
APR 22 1981
FEB 1 7 1983
DEC 1? 1989
NOV 2 5 1996