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SCIENCELIBRARY Q ſº * 22 , s/? w * Cbe Ulniversity of Cbicago FOUNDED BY JOHN D. ROCKEFELLER COMPARATIVE ANATOMY OF DUNE PLANTS A DISSERTATION SUBMITTED TO THE FACULTY OF THE OGDEN GRADUATE SCHOOL OF SCIENCE IN CANDIDACY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY (DEPARTMENT OF BOTANY) BY h sº- Q ANNA. M. STARR --~" Reprinted from THE BOTANICAL GAZETTE, Vol. LIV, No. 4, 1912 VOLUME LIV - NUMBER 4 T H E BOTANICAL GAZETTE OCTOBER 1912 COMPARATIVE ANATOMY OF DUNE PLANTS CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 16I A N N A M. S. T A R R (WITH THIRTY-FIVE FIGUREs) The literature of ecological anatomy is extensive when one con- siders that the whole subject of ecology is a late arrival in the field of botany. Comparative anatomy, ecologically viewed, is limited enough to justify a brief review. BONNIER (I) was a pioneer in experimental work, taking parts of plants growing in intermediate situations in the mountains and transplanting one part to the low- lands and another part to alpine conditions. He found that the plants grown in the two habitats differed in appearance, habit, and structure (2). GREVILLIUS (15) in an extensive work on the island Öland compared the vegetation of the alvar, a dry, rocky, treeless plain, with that of the fertile regions. CHRYSLER (7) compared the anatomy of strand plants at Woods Hole with that of the same species growing on the shores of Lake Michigan. CANNON (5) at the Desert Laboratory (Tucson) contributed some experiments on desert plants, keeping some plants under irrigation and letting others of the same species grow without irrigation, his study being a comparison of the conductive tissues. CHERMEZON (6) in a recent contribution to the anatomy of littoral vegetation makes some comparison of it with that of continental plants. All agree that the structure of plants varies with change in conditions. In 1899 CowLEs (8) published the results of his studies of the sand dunes of Lake Michigan, describing the general features of 265 266 BOTANICAL GAZETTE ſocroRER the coast, the ecological factors, and the plant associations. It was his intention to enter into an investigation of the anatomical rela- tions of the plants described, but other work prevented. In the fall of 1908 he suggested that I undertake the study, and it has been under his direction that the work has been carried on. I wish to express my grateful thanks to him and to all the members of the Tepartment who helped me with criticism and advice, and also to those who aided me in photographic work and in collecting material. In 1904 C. L. HoLTZMAN, in an unpublished dissertation, described the leaves of six of the species included in my work, and I have had access to his paper. - The dune plants were collected from the Indiana dunes, chiefly from the vicinity of Miller's, Dune Park, and Furnessville. The mesophytic forms came mainly from the flood plains of the Desplaines River at Riverside; some were collected in other meso- phytic woods in the same general locality, while a few came from the Mississippi flood plain. - The stems and roots were preserved in formalin and 50 per cent alcohol and cut with a hand microtome. The leaves that made the most successful permanent preparations were killed with corrosive sublimate dissolved in 95 per cent alcohol, used hot. These were easily sectioned in paraffin. I found 8 pm the most satisfactory thickness. Free-hand sections were also made. Safranin and anilin blue were used in staining. The names are those given in the seventh edition of GRAY's Manual and differ therefore at times from those used by CowLEs. The drawings were made by the aid of a camera lucida, magnified 470 diameters, and reduced one- half in reproduction. Ecological factors in the dunes LIGHT AND HEAT.—There is direct illumination, increased by reflection from the sand. Because of the scanty vegetation and the great exposure, the temperature of the air is higher in Summer and lower in winter than in more protected localities. Owing to the high conductivity of sand, the same great divergence between extremes is present in the temperature of the soil. WIND.—CowLEs considers this the most potent factor in determining the character of the dune vegetation. The winds 1912] STARR-ANA TOMY OF DUNE PLANTS 267 gather force as they sweep across the lake, and when they reach the shore they gather up sand and carry it along with a force that carves and scars the bark of the trees on the windward side or completely wears it away, as in the case of Cornus stolonifera. Soni. The soil is chiefly quartz sand, the particles being relatively large, so that it is extremely porous, which has a great influence on the water and heat relations. As a rule sandy soils are poor in nutrient food materials, nor do they rapidly develop a rich humus because of the rapid oxidation of the organic matter. e WATER.—The surface layer of soil is very dry, as the capillarity of sand is less than that of other soils, evaporation from a sandy surface is rapid, and precipitated water percolates quickly, the water capacity of sand being slight. On the other hand, a sandy soil yields its water to plants more freely than other soils, and below the superficial layer of dry sand there is always a surprising amount of water. FULLER (13) has found this to be more than double the wilting coefficient of dune soil, BIOTIC FACTORS.–The only biotic factors of marked influence in the dunes are those associated with the plants themselves when they are once established, humus and shade. Humus influences the temperature of the soil and increases the water content, the number of soil organisms, toxicity, and aeration. Shade influences the germination of seeds and increases the accumulation of humus and atmospheric humidity, and so decreases evaporation, FULLER (12) finds that in the cottonwood dunes the evaporation is 21 cc. per day, while on the pine dunes it is II co., in the oak dunes Io co., and in the beech-maple forest 8 cc., a descending scale from the pioneer formation to the climax forest. Description of the plants I. XEROPHYTIC FORMS Herbs - Cakile edentula.-A small, very succulent annual. Leaves smooth and thick; outer walls of epidermis 4 p.; several rows of palisade on each side with a narrow zone of sponge in the center; water-storage tissue about the bundles; stomata on both surfaces; conductive elements not well developed. Stem with epidermal walls thickened all around, the outer Io P. 268 BOTANICAL GAZETTE [October Euphorbia polygonifolia.-A little prostrate succulent annual with abundant latex. Leaves small, thick, inclined to be folded . at right angles on the midrib; walls of epidermis thickened, outer 9–12 Au on the upper surface and 15 A at the edges of the leaf; stomata sunken to the depth of the epidermis; a layer of palisade cells next the upper epidermis and “festoon” palisade about the bundles; a layer of water-storage tissue next the lower epidermis; cells at the bend of the midrib collenchymatous; Small develop- ment of vascular elements. Stem woody for so small a plant, having a compact vascular cylinder; walls of epidermis thick, outer 8 p., cuticle 4.6 p.; cells below thickened; latex tubes con- spicuous. - Corispermum hyssopifolium.—Low, branching, succulent annual. Leaf thick, narrow, linear; two layers of palisade on both sides and water-storage tissue in the center; walls of the epidermis thickened, outer I6 p.; cells with thickened walls about the midrib at the edges of the leaf. Stem with two layers of palisade in the cortex and collenchyma at the surface; walls of epidermis heavy, outer 9.6 p. Root sclerenchymatous except a few outer layers. Artemisia caudata and A. Canadensis.--Stout, bushy biennials or perennials. Leaf divided, divisions thick, smallest almost cylindrical, generally pubescent; double row of palisade on both surfaces, water-storage tissue inside; walls of epidermis thickened, outer wall 6-II pl; stomata sunken one-half the depth of the epidermal cells. Stem with pith rapidly reduced after the first year, small in older, a dense cylinder of wood extending almost to the center; great masses of fibers capping the phloem; outer layers of cortex collenchymatous; considerable cork. Cirsium Pitcheri.—Biennial, tomentose. Leaf very thick, with revolute margins; epidermal cells small, with thickened walls, outer 6.4 pl; chlorophyll confined to 2–4 outer layers of cells; the rest water-storage tissue with cells increasing in size toward the center with large air spaces between. Stem generally hollow, cortex thick, bundles few, with large vessels and masses of heavy fibers; rays wider than the bundles, the cells with thickened walls, outer cells of cortex collenchymatous. I912] STARR-ANA TOMY OF DUNE PLANTS 269 Lathyrus maritimus.--A Smooth trailing perennial herb. Leaf with palisade occupying almost half of the mesophyll, the sponge tissue rather compact; fibers above and below the bundles. Stem sharply angled; phloem capped by a heavy Crescent of Scleren- chyma; a second ring of Sclerenchyma penetrating a distance between the bundles; medullary rays thin; outer wall of epidermis 6.2 p. Root with large vessels; about one-half the pith made up of scattered masses of sclerenchyma. Ammophila arenaria.-A stout perennial grass with firm creep- ing rootstocks that anchor the dunes. Leaf with morphologically upper surface rolled in; the surface a series of ridges and grooves; bundles under the ridges; edges of the leaf and ridges strengthened with hypodermal sclerenchyma, that in the ridges extending into the bundles; upper epidermal cells large and globular, or prolonged into conical hairs; stomata on the upper surface sunken to the depth of the epidermal cells; chlorenchyma reduced to strands each side the bundles; air spaces very small; outer wall of the lower epidermis (the exposed side) 6.4 p thick, the cuticle 3.2 p. Stem with cortical tissue sclerenchymatous; walls of the epidermis slightly thickened all around. - Andropogon scoparius (bunch-grass).-Leaf stiffened with a series of bundles, large ones alternating with three small ones, the space above the small ones filled in with three or four enormous epidermal cells and smaller, hypodermal, colorless cells; epidermal cells occasionally prolonged into sharp hairs, longer than those of Ammophila; the large cells collapse at the bend of the leaf, as it folds with the upper surface in; masses of Sclerenchyma above and below the large bundles and below the middle of the small ones; chlorenchyma above the bundles; outer wall 9.3 pº; cuticle, thick; stomata on lower surface not sunken. Calamovilfa longifolia.-A rigid perennial grass with horizontal rootstocks and pubescent sheaths; another dune former. Leaf with lower surface plane; with ridges and narrow depressions on the upper surface which rolls in as in Ammophila; walls of epidermis thick, cuticle thick; bundles in the ridges with Sclerenchyma above and below, and sometimes about the phloem; hypodermal scleren- chyma next to the lower surface and at the top of the ridges; short, 270 BOTANICAL GAZETTE [OCTOBER pointed hairs on the upper surface; chlorenchyma, a layer of pali- Sade, and a layer of spherical cells about the bundles; walls of parenchyma cells sometimes folded in as in Pinus; stomata sunken as in Ammophila. Stem with bundles more numerous toward the periphery, where the cells of the fundamental tissue become Smaller; epidermal cells very small. Solidago racemosa Gillmani (fig. 1).-A perennial herb, woody at the base. Leaf with outer wall of lower epidermis 8 pm thick, cuticle 2.4 pm; chlorenchyma above and below; water-storage tissue in - the center; chlorenchyma above zºº º M ; l) | yº ſº % e e …) W. ſº º h ſº scarcely palisade-like, but of two Kº Qº º§§ } }% * or more layers of slightly elongated º Ç t 20: ſº & ſ |) ( ſ ( ſ {}}} a) º, N º Q2 D Ç NS: § 2-. tº * } º º §§ } cells forming a compact tissue; º º Ü C ſ [] tº 2.9\%. ń. O º: gº good development of bundles in v º O & w sº 02 ſº the midrib. Stem with small pith; cortex thick, containing groups of fibers and occasionally sclereids, Outer layers collenchymatous; crystals in the cells of the pith. sºs Xs ſº * § 3. te e s SSX =><>~\ Root with ground tissue of scle- renchyma; outer cells of cortex collenchymatous. FIG. I.-Solidago racemosa Gill- mani: Section of leaf. Lithospermum Gmelini.-A per- ennial herb clothed with bristly hairs. Leaf thick, coarse, rough on both surfaces, with appressed hairs, bent upward at the midrib; outer wall of epidermis thick on both surfaces, 9.34; palisade next both epidermal layers made up of a row of long cells, or of two rows of shorter cells; three layers in the center almost colorless; stomata not sunken. Stem with a Small Solid cylinder of wood made up chiefly of fibers, the vessels large; outer layers of cortex slightly collenchymatous; outer wall of epidermis 5A thick. r Arenaria stricta.-A low, tufted herb. Leaf smooth, needle- like; epidermal cells enormous, thickened on all sides especially at the edges of the leaf; outer wall 3. 2–7 p.; cuticle thick; scleren- chyma below the bundles; whole mesophyll composed of compact tissue; no palisade; crystals frequent. •. ** * * @ º tº a º • * * * ſº * •,• ſº sy © * i : * º & * @ 1912) STARR-ANA TOMY OF DUNE PLANTS 271 Opuntia Rafinesqui.-Stem doing the chlorophyll work; outer wall of epidermis 8 º' thick, cuticle 2.4 pº; several hypodermal layers of small heavy-walled cells; the chlorenchyma composed of many layers of cells elongated perpendicularly to the surface; the center of the stem occupied by a loose tissue of large colorless cells, the whole retaining water so effectually that it is difficult to dry it out even with heat and pressure; vascular system poorly developed; walls of the elements thin. Shrubs Prunus pumila.-A low shrub spreading easily in all directions and thus important in helping to make dunes stationary. Leaf thick, 216 pl; outer wall of epidermis 5–6 pm; cuticle very thick, ridged on the lower surface, the ridges so high that they fray out along the edge; cells above and below the midrib papillate and cuticle smooth, 8 pº; heavy masses of collenchyma above the stele of the midrib and several layers below, also in other large veins; great development of conductive elements; palisade double and festoon palisade above the bundles in the veins; lower cells of mesophyll palisade-like; crystals, oil, and other deposits abundant. Stem with vessels large and generally numerous; wood fibers heavy, with small lumen; groups of sclerenchyma in the cortex; cork thick. Salix syrticola.-A shrub with the same habits as Prunus pumila. Leaf with upper surface silky, lower hairy, closely serrate, glandular; stipules large; outer wall of upper epidermis thick; heavy scleren- chyma above and below the stele of the midrib, and collenchyma next the epidermis on both sides; two layers of palisade next the upper epidermis and three more layers elongated vertically. Stem with medullary rays very narrow; vessels not large but numerous; fibers heavy, with small lumen; outer layer of pith sclerenchyma- tous; outer layers of cortex collenchymatous; three rows of mechani- cal fibers in the cortex, the outermost very wide. Hudsonia tomentosa,—A bushy, heathlike shrub. Leaf small, awl-shaped, hairy on both surfaces and especially along the edges; upper epidermis composed of large cells; palisade about one-half the mesophyll of the narrow part of the leaf. Stem hairy, very woody, the vascular cylinder occupying most of the diameter, com- posed of very heavy fibers and few vessels; a few large scleren- 272 BOTANICAL GAZETTE [october chymatous cells form the pith; a few rows of cells, part of them fibrous, form the cortex. Arctostaphylos Uva-ursi.-A woody little plant trailing over the ground. Leaf thick, smooth, evergreen; outer wall of epidermis of both surfaces thick, cutinized; side walls plane, cutin sometimes 16 A thick; upper epidermis sometimes divided periclinally; bundles compactly developed, with fibers above and below; collenchyma next the epidermis; palisade several rows of shorter cells or two rows of longer; all mesophyll cells elongated perpendicularly to the surface; stomata sunken one-half the depth of the epidermal cells. Stem with xylem cylinder very woody; walls of pith and medullary ray cells heavy; cortex and phloem zones very narrow; cork layer not strikingly thick but very dense; 9 years’ growth in a stem 4 mm. in diameter. Juniperus communis (fig. 2).-An erect evergreen shrub. Leaf thick, rigid, con- vex on Qne side, concave on the other which is the morphological upper side and is most protected when the leaves are appressed to the stem; stomata on this side at the base of the epidermal cells, guard cells with thickened walls; outer and side walls of epidermis thick, outer II-13 P. with cuticle 3.2 A, hypodermis heavy; resin duct on convex side. Stem with almost no pith and heavy wood cylinder; 13 years’ stem 4 mm. in diameter; cork thick. Juniperus virginiana.-A shrub or small tree. Leaf awl- shaped; outer wall of epidermis very heavy, 9.6 A, cuticle 4.8 p.; two or three hypodermal layers on the convex side of the leaf heavily thickened; sunken stomata on upper plane surface, the protected side when the leaf is appressed. Stem with solid mass of heavy-walled tracheids and almost no pith; II growth rings in a stem 4.5 mm. in diameter; rows of Sclereids in the cortex; cork thick. FIG. 2.-Juniperus com- munis: section of leaf. 1912] STARR-ANA TOMY OF DUNE PLANTS 273 Hypericum Kalmianum (fig. 3).-A bushy shrub. Leaf revo- lute, thick, leathery; outer wall of epidermis 4.8 pm, cuticle 2.4 pm, lower epidermal cells inclined to be papillate; double palisade; stomata sunken the depth of the epidermis. Stem with vessels large, fibers heavy, lumen small; pith small, cork thick; three growth rings in a stem 3 mm. in diameter. Trees Pinus Banksiana.-Leaf shorter and thicker than in most pines; walls of epidermis heavy; outer 8 pm, cuticle 1.8 pl; hypodermis also heavy; thickness of both increased at the edges of the leaf; outer wall of endodermis thickened and lignified; mesophyll cells with infoldings in the walls; stomata deeply sunken, with an outer and inner vestibule and with walls 3.2 Pſ thick; two resin ducts. Stem with small pith; woody cylinder large, composed of a Solid mass of tra- cheids with very thick walls. Quercus velutina.--Small in comparison with many oaks, and of rather scrubby growth. Leaf thick, having a brilliantly varnished surface; sclerenchyma around the bundles of the midrib; cells above and below collenchymatous; epidermal cells over midrib papillate; outer wall of upper and lower epidermis thickened, cuticle thick; palisade double. Stem with pith star-shaped; vessels large; fibers heavy, with small lumen; medullary rays narrow, pith sclerenchymatous; an irregular band of fibers in the cortex. FIG. 3.—Hypericum Kalmianum: section of leaf. Summary of acerophytic characters The true dune plants have the following characteristics, which, with the exception of the characters of the conductive system, are generally admitted to be xerophytic: HABIT.-Low, tufted, or bushy, with short internodes (Arenaria, Artemisia, Hudsonia, Juniperus communis, J. virginiana); low 274 BOTANICAL GAZETTE [OCTOBER and spreading (Prunus pumila, Salix syrticola); low and trailing (Lathyrus, Arctostaphylos); low, with underground, creeping rootstocks (Ammophila, Calamovilfa). LEAF.—Small and awl-shaped (Arenaria, Hudsonia, Juniperus communis, J. virginiana); longer, sometimes wide but thick (Artemisia, Ammophila, Calamovilfa, Lithospermum, Prunus, Arcto- staphylos, Pinus, Hypericum, Cakile, Quercus, Corispermum); evergreen (Arctostaphylos, Juniperus communis, J. virginiana, Pinus); folded or revolute (Cirsium, Ammophila, Calamovilfa, Lithospermum, Hypericum, Euphorbia polygonifolia); succulent (Cakile, Euphorbia polygonifolia, Corispermum, slight in Artemisia, Cirsium, Solidago); hairy (Artemisia, Cirsium, Lithospermum, Salix syrticola, Hudsonia); equilateral (Cakile, Corispermum, Artemisia, Cirsium, Lithospermum). ANATOMY OF LEAF.—Outer wall of epidermis thick. (Cakile, Euphorbia polygonifolia, Corispermum, Artemisia, Cirsium, Am- mophila, Calamovilfa, Andropogon, Solidago, Lithospermum, Are- naria, Prunus pumila, Salix syrticola, Arctostaphylos, Juniperus communis, J. virginiana, Pinus Banksiana, Hypericum, Quercus velutina, Opuntia); cuticle thick (Ammophila, Calamovilfa, Andro- pogon, Solidago, Arenaria, Prunus pumila, Arctostaphylos, Junip- erus communis, J. virginiana, Pinus Banksiana, Hypericum, Quercus, Opuntia); deep, compact palisade accompanied by few air spaces in sponge (Artemisia, Lathyrus, Lithospermum, Prunus pumila, Salix syrticola, Hudsonia, Arctostaphylos, Hypericum, Quercus velutina, Cakile, Corispermum); stomata sunken (Arte- misia, Ammophila, Calamovilfa, Hypericum, Euphorbia polygoni- folia, Arctostaphylos, Juniperus communis, J. virginiana, Pinus); conductive tissue well developed (Solidago, Prunus, Arctostaphylos); mechanical tissue present as sclerenchyma (Lathyrus, Ammophila, Calamovilfa, Andropogon, Salix syrticola, Arctostaphylos, Quercus), as collenchyma (Solidago, Andropogon, Prunus, Salix syrticola, Arctostaphylos, Quercus, Euphorbia polygonifolia). ANATOMY OF STEM.–Succulent (Opuntia); conductive tissue well developed, with vessels large (Cirsium, Lithospermum, Prunus, Hypericum, Quercus), with vessels numerous (Salix syrticola, Prunus pumila); mechanical tissue present, an abundance of wood I912] STARR-ANA TOMY OF DUNE PLANTS 275 fibers giving general “woodiness” (Euphorbia polygonifolia, Arte- misia, Cirsium, Lithospermum, Prunus, Salix syrticola, Hudsonia, Arctostaphylos, Pinus, Hypericum, Juniperus communis, J. virginiana, Quercus), as Sclerenchyma (Artemisia, Lathyrus, Am- mophila, Solidago, Prunus pumila, Salix syrticola, Hudsonia, Quercus, Juniperus virginiana), as collenchyma (Artemisia, Cirsium, Solidago, Lithospermum, Salix syrticola, Pinus, Corispermum); outer wall of epidermis thick (Cakile, Euphorbia, Lathyrus, Ammo- phila, Lithospermum); cork thick (Artemisia, Prunus, Hypericum, Juniperus communis, J. virginiana). ANATOMY OF ROOT.—Sclerenchymatous generally (Cakile, Cori- spermum, Lathyrus, Solidago); collenchyma in cortex (Solidago); crystals abundant (Solidago, Arenaria, Prunus); resin (Juniperus communis, J. virginiana, Pinus); latex (Euphorbia); perhaps none but the last is related to xerophytic conditions. Slowness of growth is shown by the large number of growth rings in stems of small size (Arctostaphylos, Hypericum, Juniperus. communis, J. virginiana), testifying to adverse conditions. Suc- culency usually excludes some other factors, as hairiness and good development of conductive elements. FITTING (II) has recently shown that desert plants apparently do not need longer roots to reach an abundant water supply, as they have a most effective means of obtaining it from a very Scanty supply in the high osmotic pressure of their cell sap. Dune plants have not been examined in this respect. It may be found that they too have this “adaptation” to xerophytic conditions. II. COMPARISON OF PLANTS GROWING ON THE DUNES WITH THE SAME SPECIES GROWING IN MESOPHYTIC SITUATIONS The purpose of this part of the investigation was to find out by careful measurements just how much variation there is in species found in two widely differing habitats. The measurements of sections were made with a micrometer divided into Ioo spaces. For the measurement of the leaf, sections were made near the middle, cutting straight across the midrib; an average was taken of several measurements of one leaf and then of several leaves. For dº © o * * **, * * * * * * > • * , * a * * tº * e • * * *... • . 276 BOTANICAL GAZETTE [october the study of the conducting and mechanical tissues of the leaf, a section of the midrib was taken at the base of the blade. For the study of the stems, sections 5 mm. in diameter were used; when this was not possible, the two compared were as nearly equal as obtainable. CANNON's method of counting was adopted. A circle 14 cm. in diameter was drawn on paper and octants were marked off. With a camera lucida an image of the section was so thrown on the paper that the arc of the octant coincided as nearly as pos- sible with the periphery of the wood cylinder. The area of the octant was 18. 24 sq. cm. (14*Xo. 7845+8). Since the magnifica- tion used was IOO, the area examined was o. 19 sq. cm. or 19 sq. mm. For the size of the vessels and fibers measurements were always made in the last spring wood, or if that was not fully organized, in the preceding. In the following tables M stands for the mesophytic form and X for the dune form; T for the average thickness of leaf, with minimum and maximum in parenthesis; UE for thickness of the upper epidermis, including cuticle; P for depth of palisade; Sp for depth of sponge; LE for thickness of lower epidermis; OW for outer wall of the epidermis (including cuticle); and Cu for cuticle. The percentages are of the entire thickness of the leaf. In the table of stems N stands for the number of vessels in the octant; D for the average diameter of the larger vessels, with the maximum in parenthesis; W, the thickness of the walls of the vessels; F, the thickness of the walls of the fibers; L, the lumen of the fibers; R, the number of growth rings; G, the thickness of cork; and S, the thickness of the sclerenchyma ring or of the isolated masses of sclerenchyma that often appear in the cortex. As the size of vessels, being tubes, varies as their cross-sections and as the cross- sections vary as the squares of their radii, it is evident that the ves- sels in an octant of a mesophytic form would compare with the vessels in an octant of the corresponding dune form as the products of the number of vessels by the squares of their radii. Where the result is not evident at a glance, the radius was squared and the product found. The measurements are all in microns, though the pº is omitted after the first, as is also the per cent sign. 1912] STARR-ANA TOMY OF DUNE PLANTS 277 Trees ACER SACCHARUM Leaf Stem M X M X T. . . . . 75 g (69-93) Io.3 p. (95-109) N. . . 4I 33 UE. . . Io. 5 = 1.4 per cent 13 = I2 per cent D. . . 36 u (50) 37 u (46) P. . . . . 29.5 = 39 4O = 39 W. ... 3 3.5 Sp. . . . 29. O =39 4O = 39 F. . . . 4. 2 4. 7 LE. . . 6. o = 8 IO = IO L. . . . 6. 2 8.5 OW. . . I 6 3.5 R. . . 3-5 2-4 Cu . . . thin I. 7 C. . . . 8o 72 S. . . . 64 5O X.—Hairs on lower surface; upper epidermal cells smaller in depth, slightly larger in surface extent; outer wall and cuticle thicker; sclerenchyma around the bundles of the midrib heavier; greater development of bundles; cuticle on upper surface more strongly ridged. In both stomata on lower surface only. In all points but the thickness of the walls of the vessels and the fibers, an exception to the majority of cases examined. CELTIS OCCIDENTALIS Leaf Stem M X M X T. . . . . 65 g (87-72) I2O 9 (IO4–144) N. . . 17 I8.5 UE. . . 13 = 20 per cent 24 = 20 per cent D. . . 74 u (IoI) 74 p. (I2O) P. . . . . I4 = 22 43 =36 W. . . 2.4 3.2 Sp. . . . 24 = 37 4O = 33 F. . . . 4.8 6.4 LE. . . I4 = 21 I3 = II L. . . . 4.8 3.2 OW... o. 7 3 R. . . 7 7 Cu . . . very thin o. 7 C. . . . 48 32 S. . . . 64 8o X.—Large glandular cells frequently occupying the place of the epidermis and palisade; collenchyma below and scle- renchyma above the midrib, where neither appears in the mesophytic form; greater development of vascular elements.- Figs. 4 and 5. X-A straggling shrub, probably var. pumila; slightly greater development of vessels with heavier walls; fibers heavier, but fewer of them than in M, replaced by tracheids; cork thinner; more scleren- chyma in the cortex. 278 (OCTOBER BOTANICAL GAZETTE FRAXINUS AMERICANA Leaf M X T. . . . . I42 p. (124-159) P. . . . . 52 =36 68 = 42 Sp. . . . 68 = 48 59 =36 LE. . . II = 8 2I = I.3 OW... I .5 3 Cu . . . o. 7 I. 8 X.—Epidermal cells of greater depth; outer wall and cuticle thicker, ridged in the lower epidermis, most of the cells of the lower epidermis produced into short conical hairs, the rest into long hairs (M. Smooth); all tissue more compact; palisade deeper, tending to develop four rows (M only two); vessels in the mid- rib more numerous but not larger; walls thicker; greater development of fibers about the stele. Both have conspicuous glands on the upper surface, and stomata on lower surface only.—Figs. 6 and 7. gºrº }ſº I62 u (142-187) UE. . . II = 8 per cent I4 = 9 per cent Stem M X N. . . 22.5 I9.5 D. . . 53 p. (87) 51 u (72) W. . . 3.7 3.9 F. . . . 3.2 4.5 L. . . . 7.2 7.3 R. . . 88 I IO C. . . . 53 99 S. ... 3-5 I-2 X.—Differing from the majority in number and size of vessels and more rapid growth; walls of vessels and fibers thicker; sclerenchyma and cork heavier. In both walls of pith-cells thickened with conspicuous canals, and outer Cortex Collenchymatous, features pronounced in TNNPSW - Ç | | || \\ W ! ) \tº \ #. N |º ſ S-W WLY SUV S | | } º º ſ JTºyº }} | || $4%/\ |\ } S.r.º. tº 2 FIGs. 4–7.-Figs. 4 and 5, Celtis occidentalis: sections of leaves; fig. 4, mesophytic form; fig. 5, dune form; figs. 6 and 7, Fraxinus americana: Sections of leaves; fig. 6, mesophytic form; fig. 7, dune form. 1912) STARR-ANA TOMY OF DUNE PLANTS 279 JUGLANS CINEREA Leaf Stem M X M A T. . . . . 92 p (79–112) 148 p. (119-166) N. . . I 8 25 UE. . . I2 = 13 per cent I3 = 9 per cent D. . . 64 p. (85) 55 u (79) P. . . . . 21 = 21 39 = 26 W. . . 7.3 3.8 Sp. . . . 44 = 48 82 = 55 F. . . . 4 3.2 LE. . . I4 = 16 I4 = Io L. . . . 9.5 Q OW. . . thin 3. 7 R. . . I-6 (av. 3) I-3 C. . . . 6o 57 S. . . . 73 77 Y.—More pubescent; upper epidermal Y.—Like the majority in the greater cells smaller in depth, same in surface number of vessels of smaller area (but the extent; first layer of palisade deeper and final product greater), the smaller lumen a second layer developed; vessels in mid- of the fibers, and the heavier scle- rib of the same size but more numerous; renchyma; differing in thinner walls and more Sclerenchyma and collenchyma; cork, and occasionally large number of crystals abundant.—Figs. 8 and 9. rings produced in M - -º-º-º: Priºr tº ſº g g FIGS. 8, 9.-Juglans cinerea: sections of leaves; fig. 8, mesophytic form; fig. 9, dune form. 28o BOTANICAL GAZETTE |october LIRIOD ENDRON Leaf Stem M X M T.. . . .148 u (137-168) 21ou (190-236) N... 79 I31 UE. . . 15 = Io per cent 17 = 8 per cent D. . . 34 u (48) 32 u (41) P. . . . . 37 =25 59 = 28 W... 3.1 3-2 Sp. . . . 8o =54 III = 53 F. . . . 3.8 4.6 LE. . . 16 = 11 22 = II L. . . . Io. 7 8.5 OW... 3.3 5.6 R. . . I-3 2-5 Cu 2 C.. . . 42 5o S X-Cells of upper epidermis smaller in surface and depth, side walls plane (wavy in M); palisade deeper, sometimes of more layers; cells of upper layer each side of midrib larger than others and without chloroplasts, as if a secondary epidermis; vessels more numerous in midrib; greater masses of fibers and more collenchyma. In both, lower epi- dermis heavy-Figs. Io and II. TFT, || || Wº || || flººf ººlºº º § Yº ſº. | | || || ſº º || || º | º *A – C-X-X Twº TD º º, º ſº - º T º ſ º, º Pº TU C º W. Q. ! - - in ºrc -F- º º º * | M. ºn 7->º -º-º-º: ºn tº Yº | -- º - º ºf- fºº º | *}” FC º ſº cº- --" . º alſº hº -- () º - L º it wº º | º 11 FIGs. Io-13–Liriodendron tulipifera: sections of leaves; fig. Io, mesophytic form; fig. 11, dune form; sections of stems; fig. 12, mesophytic form; fig. 13, dune form. Like the majority in all respects. In both, sclerenchyma around the pith and groups of fibers capping the phloem- Figs. 12 and 13. 1912] 28I STARR-ANA TOMY OF DUNE PLANTS OSTRYA VIRGINIANA Leaf Stem M X M 2C T. . . . . 78 p. (66–95) IIo u (91-125) N. . . 24 59 UE. . . Io = II per cent II = Io per cent D. . . 48 p (75) 26 u (37) P. . . . . 3o = 38 43 = 39 W . . . 2.8 2.5 Sp.... 32 45 F. . . . 3.3 3.9 LE. . . 6 II L. . . . 6.7 5.6 OW... I. 3 3.2 R. . . 3 3–6 C.. . . 29 64 X.—Upper epidermis slightly thicker and wall thicker; little variation in the depth of the palisade, but the layer more compact; stomata on lower surface only (in M occasionally on the upper). X.—Rings of sclerenchyma in the cortex wider and outer layers of the pith more sclerenchymatous; in all re- spects, except as to the thickness of the wall of the vessels, agreeing with the majority. POPULUS BALSAMIFERA Leaf Stem M JK M X T. . . . . 257 p. (243-272) 212 p. (195-228) N 33 90 UE. . . 18 = 7 per cent 17 = 8 per cent D. . . 46 p. (62) 36 u (50) P. . . . . 96 = 37 94T-44 W. . . 2.9 2.6 Sp. . . . I29 89 F 4. I 3.8 LE. . . I4 I6 L. 7.2 6.8 OW... . 4.3 - 5 R I–2 2-9 Cu. . . I I. 2 C.. . IOO S. . . . 64 90 The only exception found to the general fact that dune plants have thicker leaves than mesophytic. X.-Upper epidermis and palisade relatively deeper; outer wall and cuticle thicker and ridged; more ves- sels in the midrib, larger; more fibers about the stele. Both have stomata on both surfaces; all side walls of epidermis plane except those of lower surface in M: double palisade. X.—Vessels agreeing with the majority in total area, but walls slightly thinner, walls of fibers also thinner, but lumen smaller, so the amount of wood may be the same; cork only starting to form in M. 282 BOTANICAL GAZETTE [ocTOBER POPULUS DELTOIDES Leaf M - A T.. . . . 193 u (177–227) 254 P. (236-295) UE. . . I3 = 7 per cent 18 = 7 per cent P. . . . . 62 = 32 84 = 33 Sp. . . . IoS = 54 I38 = 55 LE. ... I3 I4 = 5 OW... 2.3 4. Cu. . . o. 8 I. 3 In both lower epidermis thickened as Stem M Y N. . . 46 85 D. . . 49 u (64) 5o u (62) W. . . 2.6 2.7 F. . . . 3.8 3.9 L. . . . 6.8 6 R. ... 2 I-4 C. . . . 82 IO5 S. . . . 94 98 Agreeing with the majority in all well as upper, stomata on both surfaces points; a tendency to angled twigs and and side walls of epidermal cells plane, all star-shaped pith more marked in X. related to the movement of the leaf. X.—Upper epidermal cells smaller in surface; surface slightly hairy; palisade sometimes triple; also palisade cells near lower epidermis, separated from it by a layer of heavily walled cells, like a second- ary epidermis. Other points follow the general rule.—Figs. I4 and 15. FIGS. I.4, 15.-Populus deltoides: sec- of leaves; fig. I4, mesophytic form; he dune form. ===P C.T.E.X. Jºr ‘mirrº ſ ºf IT || || || || || || || || || || || || | | ſ || || || | \!\!\!\!\!\{*{(Lºſ A/-. i. Z 0. | | | º f || || | | W. WYT JNſ ſ j} ſ ſº f\, \! ) iſ 7 || || | 0.3% º | | ſ illº & . :^ 4. ºf # 3. & Sº-º: º 2^.2%. gº º O2 Yºereºseº º f 42 ſ f f ſ * , t § | º t | | | || 5 || || A ſ' U M º ſ ſ ſ ſº f ſ | ſ - | | ſº ſº a \ & Z\hº & W Y º f | º º | \ * Nº || § | NS º I f |Aºf J WW W º - | 1912] STARR-ANA TOMY OF DUNE PLANTS 283 TILIA AMERICANA Leaf Stem M X M Y T. . . . . 9o u (90–Io8) 138 g (135-156) N. . . 59 63 UE. . . I7 = 19 per cent 23 = 17 per cent D. . . .38 u (53) 41 u (41) P. . . . . 26 = 29 45 = 33 W. . . 2.7 2.8 Sp. . . . 36 = 46 52 = 38 F. . . . 2.8 2.4 LE. . . II = I2 17 = I2 L.... 9.6 9. I OW... 3.7 4.4 R. . . 2-5 I-5 Cu. . . I. 5 2 C.. . . 58 5o X.—Cells of upper epidermis smaller in depth, larger in surface, sometimes divided periclinally; side walls on lower surface wavy, upper and both in M In both bands of sclerenchyma in the phloem and collenchyma under the cork, slightly less in X; little variation in walls and lumina of the fibers, but plane; deeper palisade and tendency vessels more numerous and larger in X. toward second layer; midrib as in preced- ing X. In both hairs in the axils of the veins; cuticle ridged.—Figs. I6 and 17. 16 ºrrº J'ſ W ) © ) t O o O § 2—º * © º & J `-CCCCCCCCCDO-2 17 FIGS. 16 and 17.-Tilia americana: sections of leaves; fig. 16, mesophytic form; fig. 17, dune form. 284 BOTANICAL GAZETTE (OCTOBER TJLMUS AMERICANA Leaf Stem M X M X T. . . . . Io2 u (94-Io9) I74 p. (164-186) N. . . 28.5 52 - UE. . . 21 = 21 per cent 38 = 22 per cent D. . . 61 p. (IO4) 61 p. (96) P. . . . . 29 = 29 7O = 4o W... 3.7 3.3 Sp. . . . .38 = 37 51 = 29 F. . . . 5.9 5. 7 LE. . . I3 = I3 I5 = 9 L. . . . 2.9 3. 7 OW... 3.2 5.2 R. . . 5–II 5 Cu. . . thin thin C.. . . 66 66 X.—Cells of upper epidermis greater in depth; side walls plane, cuticle not ridged (in M walls slightly wavy and cuticle slightly ridged on lower surface); palisade deeper sometimes double, mid- rib structure as in other X. In both upper surface rough, hairy (X more so); some epidermal cells enormous.-Figs. 18 and 19. | ( ſº (UUUT § . . º(ſ) || ſ |}}}} O © b Vessels as in majority. X. —Walls of vessels and of fibers very slightly thinner than in M and lumina of fibers larger, yet masses of fibers so much more numerous they form more wood; cork and cortical sclerenchyma the same. FIGS. 18 and 19.-Ulmus americana: sections of leaves; fig. 18, mesophytic form; fig. 19, dune form. 1912] STARR—ANA TOMY OF DUNE PLANTS 285 Shrubs CORNUS STOLONIFERA Leaf Stem M Y M X T. . . . . 129 p. (120–144) I56 u N. . . 63 7o UE. . . I'7 = 13 per cent 15 = Io per cent D. . . 3o u (41) 33 g (45) P. . . . . 34 = 26 48 = 31 W. . . 3.2 34 Sp. . . . 56 =44 72 = 46 F. . . . 4.7 5 LE. . . 22 = 17 2I = 13 L. . . . 6.4 6, 2 OW... I .6 2 R. . . I-3 2–8 Cu. . . thin o. 8 C. . . . None except 112 (in 8-year X.—Hairs more abundant than in M, on upper surface radiating from a center parallel to the surface, tuberculate; on lower surface simple or branched; short hairs also found, formed as slight pro- longations of most of the lower epidermal cells, their cuticle prominently ridged; cells of upper epidermis smaller in all dimensions; side walls plane (wavy in M); deposits in the form of crystals and oil in the cells, and wax on the outer wall; other points as in most xerophytic forms.-Figs. 20 and 21. FIGS. 20, 21.-Cornus stolonifera: Sections of leaves; fig. 20, mesophytic form; fig. 21, dune form. at lenticels stem) : Epidermal cells when present papillate and cuticle heavy; cork not formed be- fore 5 years. In both small groups of Sclerenchyma in cortex. All points as in majority. º º 3% 0 º 00. 960 % % Á #. [] O º 286 BOTANICAL GAZETTE |october HAMAMELIS WIRGINIANA tem (figs, 22 and 23) M X N. . . 94 I57 D. . . 29 u (37) 24 u (27) W. . . 2.3 1.6 F. . . . 5.7 6.4 L. . . . 5.6 4. R. ... 3 5 C.. . . 56 48 S.. . . 64 88 º º º º º A'ſ º -- º º º º & Figs 22–25–Figs. 22 and 23, Hamamelis virginiana: sections of stems; fig. 22, mesophytic form; fig. 23, dune form; figs. 24 and 25-Prunus virginiana: sections of leaves; fig. 24, mesophytic form; fig. 25, dune form. 1912] STARR-ANATOMY OF DUNE PLANTS 287 PRUNUS VIRGINIANA Stem M X M X T. . . . . 119 u (Ioo-123) 198w (187-214) N. . . 76 IoS UE. . . 18 = 15 per cent 16 = 8 per cent D. . . .38 u (55) 35 u (45) P. . . . . 35 = 30 99 = 5o W. ... 3.1- 3.5 Sp. . . . 51 =43 66 =33 F. . . . 4.6 4.6 LE. . . I4 = 12 17 = 9 L. . . . 4.7 4-4 OW... 2.9 6.7 R. . . .3 3-6 Cu. . . 1.1 1.8 C. . . . 42 61 S. . . . 83 51 X-Hairs on lower surface (none in M); cells of upper epidermis larger in surface, of less depth, cuticle more prominently ridged than in M, side walls less wavy; palisade double (some- times so in M, but cells are not so long nor so compact as in X); midrib as in other X (sometimes in M sclerenchyma below the stele is scarcely perceptible); oil drops, especially in epidermis and upper part of palisade; crystals and other deposits about the bundles.-Figs. 24 and 25. FIGs. 26–27.-Prunus virginiana: sec- tions of stems; fig. 26, mesophytic form; fig. 27, dune form. Only exception to the majority rule is the sclerenchyma, which is heavier in some mesophytic forms—Figs. 26 and 27. º º º - E. º º E. - -- º: : - 288 BOTANICAL GAZETTE |october PTELEA TRIFOLIATA Leaf Stem M X M X T . . . . 147 u (131-156) 185 u (177-193) N . . . 51 51 UE. . . 14 = 9 per cent 18 = Io per cent D . . . 53 u (73) 55 u (82) P . . . . 42 = 29 56 =3o W . . . 2.2 3. I Sp . . . 78 =53 95 =51 F 2 2.9 LE. . . 13 = 9 16 =9 L 8.4 7.2 OW . . . .2 4.8 R . . . 2-3 4-7 Cu . . . thin I .3 C . . , 5o 83 X-Hairs abundant on lower surface (none in M); cells of upper epidermis slightly larger in surface; side walls on both surfaces plane and cuticle ridged (in M wavy and only slightly ridged); palisade, sponge, and midrib as in other X. One tree in an especially exposed situation, near the top of a wind sweep leading up from the lake, probably once a mesophytic pocket, had a more pro- nounced structure than the one figured; the leaf averaged 21 ou in thickness, with an outer wall 6.4–8.4, heavily cutinized. Figs. 28–29–Pleled trifoliata: sec- tions of stems; fig. 28, mesophytic form; fig. 29, dune form. Agreeing with the majority, except that collenchyma in outer cortex may be no heavier in X-Figs. 28 and 29. 1912) 289 STARR-ANA TOMY OF DUNE PLANTS SALIX LONGIFOLIA Leaf Stem M X M X T. . . . . 152 p. (136–168) 188 u (162–212) N. . . 77 66.5 UE. .. 8 = 5 per cent I2 = 6 per cent D. . . 36 A (53) 43 * (55.5) Mes. . 133 = 88 165 =88 W. . . 2.4 2.4 LE. . . II = 7 II = 6 F. . . . 2.8 3 OW... I .5 3 L. . . . 5.3 6.7 Cu. . . thin 2 R... 4 2 C.. . . 33 32 S. . . . 33 48 Equilateral; two rows of palisade on each side beneath a hypodermis, differ- entiated as a special storage region; stomata on both surfaces, slightly sunken. X.—Upper palisade cells more elongated; Sclerenchyma and collenchyma more abundant in midrib. Y.—Agreeing with the majority in the greater area of vessels and greater num- ber and size of sclerenchyma masses in the cortex; exceptional in the larger lumen of the fibers and fewer growth rings. Lianas CELASTRUS SCANDENS Leaf Stem M M M X T. . . . . IoI u (92-123) I64 u (138-174) N. . . 36 7 UE. . . I4 = I4 per cent 22 = I4 per cent D. . . 54 u (78) 45.5 H (69) P. . . . . 25 = 25 43 = 26 W . . . 2.8 3.6 Sp. . . . 49 = 48 8I = 49 F. . . . 4.9 4.5 LE. . . I3 = I3 I8 = II L. . . . 8.4 7.5 OW e 4. R. . . I-3 I-3 Cu ! thin I. 7 C.. . . 8o 76 Y.—Coarse, often merely acute; veins prominent on the under side. M.– Smooth and fine, long acuminate; veins not prominent on under side; other variations as usual. Chiefly an exception; M greater in area of vessels, heavier fibers and cork. X follows the majority in having heavier sclerenchyma around the pith, thicker. walls of the vessels, and smaller lumina in the fibers. 290 BOTANICAL GAZETTE [OCTOBER PSEDERA QUINQUEFOLIA Leaf Stem * M Y M X T..... IIe u (99-130) 183 p. (164–195) N. . . 36 40.5 UE. . . I4 = 13 per cent 21 = II per cent D. . . 78 p. (I2O) 61 p. (90) P. . . . . 24 = 22 . 56 = 31 W . . . 2.8 3.4 Sp. . . . 59 = 53 90 = 49 F. . . . 4.6 5.9 LE. . . I3 = I2 I6 = 9 L. . . . 7.2 4.7 OW... I. 5 3 R. . . I I - 2 Cu. . . o. 7 I. 5 C. . . . I96 I88 S. . . . II 2 62 In both side walls of epidermal cells Exceptional in the smaller area of plane except in lower surface of M, cross-sections of vessels in X, less scle- cuticle ridged, hairs on the lower surface. renchyma and cork; the cork is loose X.-Epidermal cells larger in surface, and shreds off, so more may have been smaller in depth; other points as usual lost in X than in M, the other points except there is not greater development agree with the majority. of conductive tissues.—Figs. 3o and 31. FIGS. 30, 31.-Psedera quinquefolia: Sections of leaves; fig. 30, mesophytic form; fig. 31, dune form. 1912] STARR-ANATOMY OF DUNE PLANTS 29I RHUS TOXICODENDRON Leaf Stem M X M X T. . . . . 79 p. (73-II6) I4o u (123-198) N. . . 35.5 18.5 UE. . . 9 = II per cent I2 = 9 per cent D. . . 85 H (99) 69 p. (88) P. . . . . 25 = 33 45 = 32 W. . . 2 2.4 Sp. . . . 37 = 46 7o = 56 F. 2.4 2.8 LE. . . 8 = Io I2 = 9 L. 9.6 7.2 OW... I. 9 2.7 R. . . 2 3 Cu. . . thin I. 4 C. . . . I83 I45 X.—Epidermal cells smaller in depth; Exceptional but in the mass of wood occasional indications of a double pali- formed. sade; other points as usual.-Figs. 32 and 33. - FIGS. 32–33.-Rhus toxicodendron: Sections of leaves; fig. 32, mesophytic form; fig. 33, dune form. 292 BOTANICAL GAZETTE ſocTOBER SMILAX HISPIDA Leaf Stem (Quadrant used instead of octant) M X M X T. . . . . Ioff u (96-129) I68 u (157-204) N. . . 6 bundles; each 6 UE. . . II = II per cent 22 = 13 per cent with 2 large 2 Mes. . 82 = 77 I24 = 74 vessels and 18 13 LE. . . I3 = I2 22 = 13 smaller OW... I 5 - 3. 7 D. . . of large ves- Cu. . . thin I sels IoS IoW t W... 4 4. F. . . . 3.2 3.6 L. . . . 5.9 4.3 OW... I 8 22 X.—Epidermal cells deeper and larger in surface extent; outer wall and cuticle heavier; cuticle more strongly ridged; side walls less wavy; more conductive and mechanical tissues, but walls thinner. The mesophyll shows the usual monocot variation, no differentiation into palisade and Sponge. X.—Two vessels larger, but not so many small ones; cortex more collen- chymatous; pith cells with thicker walls, pith packed with starch grains and Crystals. VITIS VULPINA Leaf Stem M M M Y T. . . . . IoS u (Ioo-II8) I53 u (127-164) N. . . 9 IO UE. . . I4 = 13 per cent I3 = 9 per cent D. . . IoS M (142) Io2 p. (127) P. . . . . 28 45 = 29 W. . . 4 4.5 S. . . . . 5o 8I = 53 F. . . . 5.2 4.8 LE. . . I3 I4 = 9-H L. . . . 7.2 7. I OW g I. 8 R. . . 2-3 2–3 Cu ! thin C. . . . 236 3O7 X.—Upper epidermal cells smaller in X.—Slightly more area in cross- depth, larger in surface; hairs on veins on both surfaces (only on upper in M); other points as usual. In both walls plane and cuticle somewhat ridged. sections of vessels; cork thicker; less sclerenchyma. - 1912] STARR-ANATOMY OF DUNE PLANTS 293 Herbs ASCLEPIAS SYRIACA Leaf Stem M X M X T. . . . . 225 g (230–296) 272 u (237-304) N. . . . . . . 25 I8 UE. . . 25 = Io per cent 25 = 9 per cent D. . . . . . . 46 u (66) 64 u (87) P. . . . . 54 = 21 77 = 28 W . . . . . . . 3.5 4.6 Sp. . . . I58 = 62 I5I = 56 F. . . . . . . 2.9 3.5 LE. . . 18 = 7 I9 = 7 L. . . . . . . I7 I5 OW... 2.4 2.4 OW. . . . . . 4. 6.4 Wood cyl 185 61 I In both side walls of upper epidermal cells plane, of lower wavy; cuticle ridged on lower surface. X.-Hairs on both surfaces (only on lower in M); upper epidermal cells smaller in depth, larger in surface; palisades often deep in pro- portion to sponge; where not, a secondary palisade partly organized; conductive and supporting tissues as usual; latex and other secretions more abundant.— Figs. 34 and 35. X.—Area of cross-sections of vessels smaller, larger cylinder of wood formed; walls of vessels and of fibers heavier, lumen of fibers smaller, so more wood; outer wall of epidermis and hypodermal collenchyma heavier. SMILACINA STELLATA Leaf Stem M M M JC T. . . . . I74 u (155-199) 202 u (182-242) Bundles in field. . I2 I 2 UE. . . 28 = 16 per cent 3o = I5 per cent N in bundle. . . . . I5 I3 M. . . . II9 = 68 I44 = 7I D. . . . . . . . . . . . . . 27 p. 32 A. LE. . . 27 = 16 29 = I4 W. . . . . . . . . . . . . . 4. 3 4.5 OW. . . 2.6 2.9 OW. . . . . . . . . . . . 7.2 6.4 Cu. . . o. 7 o. 7 X.—Epidermal cells smaller in depth, larger in surface; hairs more abundant, more crystals deposited; other variations as usual; in both no differentiation in the mesophyll, the general monocot situation; side walls of epidermal cells plane. X.—Area of cross-sections of vessels greater; walls of vessels heavier, but outer wall thinner. 294 . BOTANICAL GAZETTE - {October FIGS. 34, 35-Asclepias Syriaca: sections of leaves; fig. 34, mesophytic form; fig. 35, dune form. 1912] STARR-ANATOMY OF DUNE PLANTS 295 Swamp forms Sometimes a moving dune passes over a swamp association, and the members by increased length of stem keep pace with it for a time; a few of these have been examined and compared with forms growing in their natural habitat. PLATANUS OCCIDENTALIS Leaf Stem S Y º T. . . . . 152 w (136-162) 199 u (162-205) N. . . . 66 69 UE. . . 23 = 15 per cent 25 = I2 per cent D . 35 u (50) 46 p. (63) P. . . . . 52 =34 63 = 32 - W 3.2 3.2 Sp. . . . 62 =41 92 = 46 F. . . . . 5 3.2 LE. . . I6 = Io I9 = Io L. . . . . 6.4 7 OW... 4 2.8 R. . . . 3 2 C . 68 6.9 S. . . . . Ioo II6 Collen 56 Io9 The dune form has thicker leaves than the swamp form, but the palisade and outer wall of the epidermis are excep- tional. The dune form shows an increase in number and size of the vessels, but there is no increase in woody tissue furnished by the fibers. There seems to be no diminution in growth as indicated by the growth rings, but mechanical tissue outside the stele and the cork have in- creased. ALNUS INCANA Stem S X N. . . . . . . . . . . . . . . . . . . . . 68 6I Swamp form, vessels larger than the D. . . . . . . . . . . . . . . . . . . . . 29 34 others but fewer in number. Dune W. . . . . . . . . . . . . . . . . . . . . 2.5 2.6 form, larger area of vessels. Thickness F. . . . . . . . . . . . . . . . . . . . . 3.5 3.4 of walls about the same. L. . . . . . . . . . . . . . . . . . . . . . 7 8.8 CEPHALANTHUS OCCIDENTALIS S Leaf T... 175 u (143–168) 163 u (147-189) A second layer of palisade is partly UE 16 = 9 per cent 17 = Io per cent organized in the swamp form and com- P... 54 =3|I 48 = 29 pletely in the dune form. The first Sp.. 91 =52 84 = 52 palisade is relatively shorter in the dune LE. I.4 = 8 I4 = 9 form, but the second is so much more OW 3 3.7 compact than in the swamp form that it Cu. I.6 2 must more than make up the amount of tissue. In both forms stomata are found on the lower surface only and the side walls of the epidermal cells are waxy. 296 BOTANICAL GAZETTE ſocroBER SALIX GLAUCOPHYLLA Leaf Stem M M S X T. . . . . 185 u (180–208) 231 u (219–240) N. . . . 57 64 UE. . . 20 = Io per cent I9 = 9 per cent D. . . . 45 47 P. . . . . 92 = 50 I2O = 52 W. . . . 2.3 2.4 Sp. . . . 57 =31 69 =30 F. . . . . 3. I 4.8 LE . . . I6 = 8 I9 = 9 L. . . . . 5 3.2 OW... 4.3 4.8 R. . . . 2-4 4. Cu. I.6 I. 6 Cork... 56 8o Collen 4–6 layers 7 layers Little variation, but the palisade is In the dune form more vessels and slightly deeper in the dune form; the larger; the fibers heavier and the lumina vessels of the midrib are larger though smaller, giving more wood; growth rings about as numerous, their walls are heavier about the same; more cork, collenchyma, as is also the outer epidermal wall, and and sclerenchyma. there is more collenchyma. CORNU'S STOLONIFERA A plant growing on the edge of a river was partly submerged by a dune. The stem was examined to find the difference between the submerged and the aerial parts. Submerged Aerial Cortex and phloem. . . . . . . . . . . . . . 4OO At 380 p. Wood cylinder. . . . . . . . . . . . . . . . . . 836 95o Pith. . . . . . . . . . . . . . . . . . . . . . . . . . . I976 1482 32 I.2 281.2 The upper exposed part is not as large as the submerged part, but the wood cylinder is larger. Submerged Aerial N. . . . . . . . . . . . . . . . . . . . . . 62 44 D. . . . . . . . . . . . . . . . . . . . . . 23 38 W. . . . . . . . . . . . . . . . . . . . . . 2. 3 3.2 F. . . . . . . . . . . . . . . . . . . . . . 5. I 5.6 L. . . . . . . . . . . . . . . . . . . . . . IO. 4 5.6 In a given area in the cylinder there are fewer vessels, larger in diameter but less in area, which must be more than compensated for by the size of the whole cylinder. The walls of the vessels and fibers are heavier and the lumina of the fibers smaller, giving more wood. SALIX LONGIFoETA Situation the same, but the parts examined were not parts of the same stem, but were of the same size. Submerged Aerial N. . . . . . . . . . . . . . . . . . . . . . 42 SI D. . . . . . . . . . . . . . . . . . . . . . 4I 43 W. . . . . . . . . . . . . . . . . . . . . . 3. 2 2 - 4 F. . . . . . . . . . . . . . . . . . . . . . 3 3.2 L. . . . . . . . . . . . . . . . . . . . . . 7.7 6.8 In aerial stem more and larger vessels, walls slightly thicker, lumina of fibers smaller, giving more wood. The swamp forms on the whole show the same variations as the mesophytic forms. 1912] STARR-ANATOMY OF DUNE PLANTS 297 Table (I) on p. 298 gives a comparison of mesophytic and dune forms of the same species with respect to eleven characters of the leaf. A summary of leaf characters is as follows: Hairs more abundant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I2 X (3 same) Surface of upper epidermal cells greater. . . . . . . . . . . . . . 9 X- 5 M (2 same) Depth of upper epidermal cells greater. . . . . . . . . . . . . . . 5 X-12 M (4 same) Side walls of upper epidermal cells wavy. . . . . . . . . . . . . . 6 X—II M Side walls of lower epidermal cells wavy . . . . . . . . . . . . . . 8 X—I6 M Outer wall of epidermis heavier. . . . . . . . . . . . . . . . . . . . . . I8 X (2 Same) Cuticle ridged. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Io X— 6 M Palisade more completely organized. . . . . . . . . . . . . . . . . . 17 X (I Same) Better development of conductive elements. . . . . . . . . . . I5 X- 2 M (I same) Heavier Sclerenchyma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I4 X— I M (I same) Heavier collenchyma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 X -* ------ ** Ar / All leaves, with the exception of those of Populus balsamifera, (were thicker in the dune form than in the mesophytic. The poplar was growing alone at the side of a road, so the exposure was greater than in the woods where most of the mesophytic specimens were collected. The bud scales also were thicker, and in most cases the outer wall, or the cork if it had developed, was thicker. The greater extent of surface in the upper epidermal cells in the majority of the dune forms is striking. GREVILLIUS speaks of epidermal cells in the alvar plants being Smaller than in the normal, but he may have used the lower surface only, as he mentions the subject in connection with stomata, and that may differ from the upper surface. Cuticular transpiration is reported as taking place from the side walls of the epidermal cells more abundantly than from the lumen of the cell. If this is true, then increase in the surface extent of the cell would decrease cuticular transpiration. The apparent thickness of the epidermis of dune forms is due to the heavy wall and cuticle and not to the depth of the cells. Waviness of the side walls seems to be related to shade, as it occurs more frequently in mesophytic leaves, and in mesophytic leaves on the under side. ! Ridging of the cuticle accompanies great thickness. Deep, Ömpact palisade, well developed conductive elements, heavy Sclerenchyma, and the presence of hairs are characters noted §. : a & A TABLE I LEAF CHARACTERS OF MESOPHYTIC AND DUNE FORMS COMPARED 5 § -3 § 33 § ..Sº 3 | # : 5 gå | ##|...}| s #| # * | #| || 3 |#| | | | |#|5|##|##|##| || 4 || 3 || || || 4 ||a Q # © º tº 3; 3: 5.5 | # $2 # © ‘ā ă : = | #