Part 19

Leaves 2½°—3° long, about 1½′ wide, gradually narrowed upward from the comparatively thin lustrous red base to above the middle, flat except toward the apex, smooth, light yellow-green, with a long rigid sharp light red tip, and thick entire red-brown margins finally separating into short thin brittle threads. Flowers from July to September in erect stalked tomentose panicles; perianth 1′—1¾′ long, the broad oval or oblong-obovate thin segments pubescent on the outer surface toward the base and furnished at the apex with conspicuous clusters of white tomentum; stamens about two thirds as long as the ovary, with filaments pilose at the base, and only slightly enlarged at the apex. Fruit ripening in October and November, obscurely angled, 3½′—4′ long, about 1¼′ thick, often narrowed above the middle, with a stout thick point, and thin succulent flesh; seeds ¼′ wide, about ⅛′ thick, with a thin conspicuous marginal rim.

A tree, in Arizona rarely 18°—20° high, with a trunk often crooked or slightly inclining and simple or furnished with 2 or 3 short erect branches, covered below with dark brown scaly bark, roughened for many years by persistent scars of fallen leaves, and clothed above by the pendant dead leaves of many seasons.

Distribution. Dry slopes of the mountain ranges of Arizona near the Mexican boundary usually at altitudes between 5000° and 6000°, and southward into Sonora.

6. Yucca Faxoniana Sarg. Spanish Dagger.

Leaves 2½°—4° long, 2½′—3′ wide, abruptly contracted above the conspicuously thickened lustrous base, widest above the middle, flat on the upper surface, thickened and rounded on the lower surface toward the base, rigid, smooth and clear dark green, with a short stout dark tip, and brown entire margins breaking into numerous stout gray or brown fibres short and spreading near the apex of the leaf, longer, more remote, and forming a thick cobweb-like mass at their base. Flowers appearing in April on thin drooping pedicels, in dense many-flowered glabrous panicles 3°—4° long, with elongated pendulous branches; perianth 2½′ long, the segments thin, concave, widest above the middle, narrowed at the ends, united at base into a short tube, those of the outer rank being about half as wide as those of the inner rank and two thirds as long; stamens much shorter than the ovary, with slender filaments pilose above the middle and abruptly dilated at apex; ovary conspicuously ridged, light yellow marked with large pale raised lenticels, and gradually narrowed into an elongated slender style. Fruit ripening in early summer, slightly or not at all angled, abruptly contracted at apex into a long or short hooked beak, 3′—4′ long, 1′—1½′ thick, light orange-colored and lustrous when first ripe, becoming nearly black, with thick succulent bitter-sweet flesh; seeds ¼′ long, about ⅛′ thick, with a narrow nearly obsolete margin to the rim.

A tree, often 40° high, with a trunk sometimes 2° in diameter above the broad abruptly enlarged base, unbranched or divided into several short branches, and covered above by a thick thatch of the pendant dead leaves of many seasons; frequently smaller and until ten or twelve years old clothed from the ground with erect living leaves. Bark near the base of old trees dark reddish brown, ⅓′—½′ thick, broken on the surface into small thin loose scales.

Distribution. Common on the high desert plateau of southwestern Texas.

7. Yucca brevifolia Engelm. Joshua Tree.

_Yucca arborescens_ Trel.

Leaves 5′—8′ or on young plants rarely 10′—12′ long, ¼′—½′ wide, rigid, crowded in dense clusters, lanceolate, gradually tapering from the bright red-brown lustrous base, bluish green and glaucous, smooth or slightly roughened, concave above the middle, with a sharp dark brown tip, and thin yellow margins armed with sharp minute teeth; persistent for many years. Flowers appearing from March until the beginning of May, the creamy white closely imbricated bracts of the nearly sessile pubescent panicle forming before its appearance a conspicuous cone-like bud 8′ or 10′ long; perianth globose to oblong, 1′—2′ long, greenish white, waxy, dull or lustrous, its segments slightly united at the base, keeled on the back, thin below the middle, gradually thickened upward into the concave incurved rounded tip, those of the outer rank rather broader, thicker, and more prominently keeled than those of the inner rank, glabrous or pubescent; stamens about half as long as the ovary, with filaments villose-papillate from the base; ovary conic, 3-lobed above the middle, bright green, with narrow slightly developed septal nectar-glands, and a sessile nearly equally 6-lobed stigma. Fruit ripening in May or June, spreading or more or less pendant at maturity, oblong-ovoid, acute, slightly 3-angled, 2′—4′ long, 1½′—2′ thick, light red or yellow-brown, the outer coat becoming dry and spongy at maturity; seeds nearly ½′ long, rather less than 1/16′ thick, with a broad well-developed margin to the rim, and a large conspicuous hilum.

A tree, 30°—40° high, with a trunk 2°—3° in diameter, rising abruptly from a broad thick basal disk, thick tough roots descending deeply into the soil, and stout branches spreading into a broad, often symmetrical head formed by the continued forking of the branches at the base of the terminal flower-clusters; the stem until 8°—10° high simple and clothed to the ground with leaves erect until after the appearance of the first flowers, then spreading at right angles and finally becoming reflexed. Bark 1′—1½′ thick, deeply divided into oblong plates frequently 2° long. Wood light, soft, spongy, difficult to work, light brown or nearly white; sometimes cut into thin layers and used as wrapping material or manufactured into boxes and other small articles. The seeds are gathered and eaten by Indians.

Distribution. Southwestern Utah to the western and northern rim of the Mohave Desert in California; most abundant and of its largest size on the foothills on the desert slope of the Tehachapi Mountains, California.

8. Yucca gloriosa L. Spanish Dagger.

Leaves 2°—2½° long, gradually narrowed above the broad base and then gradually broadened to above the middle, thin, flat or slightly concave toward the apex, frequently longitudinally folded, dull often glaucous green, roughened on the under surface especially above the middle, with a stout dark red tip, and pale margins serrulate toward the base of the leaf, with minute early deciduous teeth, or occasionally separating into thin fibres. Flowers in October, in pubescent or glabrate panicles, 2°—4° long, on stout stalks sometimes 3°—4° in length, their large creamy white bracts forming before the panicle emerges a conspicuous egg-shaped bud 4′—6′ long; perianth when fully expanded 3½′—4′ across, its segments thin, ovate, acute, or lance-ovate, often tinged with green or purple, slightly united at the base, pubescent at apex; stamens about as long as the ovary, with hispid or slightly papillose filaments and deeply emarginate anthers; ovary slightly lobed, 6-sided, light green, gradually narrowed into the elongated spreading stigmatic lobes. Fruit very rarely produced, prominently 6-ridged, pendulous, 3′ long, 1′ in diameter, cuspidate, raised on a short stout stipe, with a thin leathery almost black outer coat; seeds ¼′ wide and about 1/36′ thick, with a smooth coat and a narrow marginal rim.

A tree, with a trunk occasionally 6°—8° high and 4′—6′ in diameter, simple or rarely furnished with a few short branches and usually clothed to the base with pendant dead leaves; in cultivation often becoming much larger, with a stout trunk covered with smooth light gray bark, and erect or in one form (var. _recurvifolia_ Engelm.) pendulous leaves.

Distribution. Sand dunes and the borders of beaches of the seacoast from North Carolina to northern Florida.

Often cultivated with many forms in the gardens and pleasure-grounds of all temperate countries.

9. Yucca elata Engelm. Spanish Dagger.

1. _Yucca radiosa_ Trel.

Leaves 20′—30′ long, ¼′—½′ wide, rigid, gradually narrowed from the thin base, tapering toward the apex, or sometimes somewhat broadest at the middle, thin, flat on the upper surface, slightly thickened and rounded on the lower surface toward the base, smooth, pale yellow-green, with a slender stiff red-brown tip, and thickened entire pale margins soon splitting into long slender filaments. Flowers in May and June on slender spreading more or less recurved pedicels, in glabrous much-branched panicles 4°—6° long, raised on stout naked stem 3°—7° in length; perianth ovoid and acute in the bud, when fully expanded 3½′—4′ across, its segments united at the base into a short slender distinct tube, ovate or slightly obovate, those of the outer rank usually acute, not more than half as broad as those of the inner rank; stamens as long or a little longer than the ovary, with slender nearly terete filaments; ovary sessile, almost terete, pale green, abruptly contracted into the stout elongated style. Fruit an erect oblong capsule rounded and obtuse at the ends, tipped by a short stout mucro, conspicuously 3-ribbed, with rounded ridges on the back of the carpels, 1½′—2′ long, 1′—1½′ wide, with a thin firm light brown ligneous outer coat closely adherent to the lustrous light yellow inner coat, in ripening splitting from the top to the bottom between the carpels, and through their backs at the apex; seeds ⅓′ wide and about 1/32′ thick, with a smooth coat and a thin brittle wide margin to the rim.

A tree, with a rough much-branched underground stem penetrating deep into the soil and a trunk often 15°—20° high and 7′—8′ in diameter, covered above with a thick thatch of the pendant dead leaves of many years, simple, or branched at the top with a few short stout branches densely covered with leaves at first erect, then spreading nearly at right angles, and finally pendulous. Bark dark brown, irregularly fissured, broken into thin plates, about ¼′ thick. Wood light, soft, spongy, pale brown or yellow.

Distribution. High desert plateaus from southwestern Texas to southern Arizona; southward into northern Mexico; most abundant and of its largest size on the eastern slope of the continental divide in southern New Mexico and along the northern rim of the Tucson Desert in Arizona.

Division II. Dicotyledons.

Stems formed of bark, wood, or pith, and increasing by the addition of an annual layer of wood inside the bark. Parts of the flower mostly in 4’s and 5’s; embryo with a pair of opposite cotyledons. Leaves netted-veined.

_Subdivision 1._ Apetalæ. Flowers without a corolla and sometimes without a calyx (with a corolla in _Olacaceæ_).

Section 1. Flowers in unisexual aments (_female flowers of Juglans and Quercus solitary or in spikes_); ovary inferior (_superior in Leitneriaceæ_) when calyx is present.

V. SALICACEÆ.

Trees or shrubs, with watery juice, alternate simple stalked deciduous leaves with stipules, soft light usually pale wood, astringent bark, scaly buds, and often stoloniferous roots. Flowers appearing in early spring usually before the leaves, solitary in the axils of the scales of unisexual aments from buds in the axils of leaves of the previous year, the male and female on different plants; perianth 0; stamens 1, 2 or many, their anthers introrse, 2-celled, the cells opening longitudinally; styles usually short or none; stigmas 2—4, often 2-lobed. Fruit a 1-celled 2—4-valved capsule, with 2—4 placentas bearing below their middle numerous ascending anatropous seeds without albumen and surrounded by tufts of long white silky hairs attached to the short stalks of the seeds and deciduous with them; embryo straight, filling the cavity of the seed; cotyledons flattened, much longer than the short radicle turned toward the minute hilum.

The two genera of this family are widely scattered but most abundant in the northern hemisphere, with many species, and are often conspicuous features of vegetation.

CONSPECTUS OF THE GENERA.

Scales of the aments laciniate; flowers surrounded by a cup-shaped often oblique disk; stamens numerous; buds with numerous scales. 1. Populus. Scales of the aments entire; disk a minute gland-like body; stamens 1, 2 or many; buds with a single scale. 2. Salix.

1. POPULUS L. Poplar.

Large fast-growing trees, with pale furrowed bark, terete or angled branchlets, resinous winter-buds covered by several thin scales, those of the first pair small and opposite, the others imbricated, increasing in size from below upward, accrescent and marking the base of the branchlet with persistent ring-like scars, and thick roots. Leaves involute in the bud, usually ovate or ovate-lanceolate, entire, dentate with usually glandular teeth, or lobed, penniveined, turning yellow in the autumn; petioles long, often laterally compressed, sometimes furnished at the apex on the upper side with 2 nectariferous glands, leaving in falling oblong often obcordate, elliptic, arcuate, or shield-shaped leaf-scars displaying the ends of 3 nearly equidistant fibro-vascular bundles; stipules caducous, those of the first leaves resembling the bud-scales, smaller higher on the branch, and linear-lanceolate and scarious on the last leaves. Flowers in pendulous stalked aments, the pistillate lengthening and rarely becoming erect before maturity; scales obovate, gradually narrowed into slender stipes, dilated and lobed, palmately cleft or fimbriate at apex, membranaceous, glabrous or villose, more crowded on the staminate than on the pistillate ament, usually caducous; disk of the flower broadly cup-shaped, often oblique, entire, dentate or irregularly lobed, fleshy or membranaceous, stipitate, usually persistent under the fruit; stamens 4—12 or 12—60 or more, inserted on the disk, their filaments free, short, light yellow; anthers ovoid or oblong, purple or red; ovary sessile in the bottom of the disk, oblong-conical subglobose or ovoid-oblong, cylindric or slightly lobed, with 2 or 3 or rarely 4 placentas; styles usually short; stigmas as many as the placentas, divided into filiform lobes or broad, dilated, 2-parted or lobed. Fruit ripening before the full growth of the leaves, greenish, reddish brown, or buff color, oblong-conic, subglobose or ovoid-oblong, separating at maturity into 2—4 recurved valves. Seeds broadly obovoid or ovoid, rounded or acute at the apex, light chestnut-brown; cotyledons elliptic.

Populus in the extreme north often forms great forests, and is common on the alluvial bottom-lands of streams and on high mountain slopes, ranging from the Arctic Circle to northern Mexico and Lower California and from the Atlantic to the Pacific in the New World, and to northern Africa, the southern slopes of the Himalayas, central China, and Japan in the Old World. Of the thirty-four species now generally recognized fifteen are found in North America. The wood of many of the American species is employed in large quantities for paper-making, and several species furnish wood used in construction and in the manufacture of small articles of wooden ware. The bark contains tannic acid and is used in tanning leather and occasionally as a tonic, and the fragrant balsam contained in the buds of some species is occasionally used in medicine. The rapidity of their growth, their hardiness and the ease with which they can be propagated by cuttings, make many of the species useful as ornamental trees or in wind-breaks, although planted trees often suffer severely from the attacks of insects boring into the trunks and branches. Of the exotic species, the Abele, or White Poplar, _Populus alba_ L., of Europe and western Asia, and its fastigiate form, and the so-called Lombardy Poplar, a tree of pyramidal habit and a form of the European and Asiatic _Populus nigra_ L., and one of its hybrids, have been largely planted in the United States.

_Populus_, of obscure derivation, is the classical name of the Poplar.

CONSPECTUS OF THE NORTH AMERICAN SPECIES.

Stigmas 2, 2-lobed, their lobes filiform; leaf stalks elongated, laterally compressed; buds slightly resinous. Leaves finely serrate; winter-buds glabrous. 1. P. tremuloides (A, B, F, G). Leaves coarsely serrate; winter-buds tomentose or pubescent. 2. P. grandidentata. Stigmas 2—4, 2-lobed and dilated, their lobes variously divided; buds resinous. Leaf-stalks round. Leaves tomentose below early in the season, broadly ovate, acute or rounded at apex. 3. P. heterophylla (A, C). Leaves glabrous or pilose below. Leaves dark green above, pale, rarely pilose below. Ovary and capsule glabrous. 4. P. tacamahacca (A, B, F). Ovary and capsule tomentose or pubescent. 5. P. trichocarpa (B, F). Leaves light green on both surfaces, glabrous. Leaves lanceolate to ovate-lanceolate. 6. P. angustifolia (F). Leaves rhombic-lanceolate to ovate. 7. P. acuminata (F). Leaf-stalks laterally compressed. Leaves without glands at apex of the petiole, coarsely serrate, thick. Pedicels shorter than the fruit. Disk cup-shaped. Branchlets stout; capsule ⅓′—½′ long. 8. P. Fremontii (G, H). Branchlets slender; capsule not more than ¼′ long. 9. P. arizonica (F, H). Disk minute. Branchlets glabrous; leaves broad-ovate to deltoid, long-pointed and acuminate at apex. 10. P. texana (C). Branchlets pubescent; leaves broad-ovate, abruptly short-pointed or acute at apex. 11. P. McDougallii (G, H). Pedicels 2 or 3 times longer than the fruit; leaves broadly deltoid, abruptly short-pointed. 12. P. Wislizenii (E, F). Leaves furnished with glands at apex of the petiole. Branchlets stout; leaves thick. Winter-buds puberulous; leaves coarsely serrate; branchlets light yellow. 13. P. Sargentii (F). Winter-buds glabrous; leaves less coarsely serrate; branchlets gray or reddish brown. 14. P. balsamifera (A, C). Branchlets slender; leaves thin, ovate, cuneate or rounded at base, finely serrate. 15. P. Palmeri (E).

1. Populus tremuloides Michx. Aspen. Quaking Asp.

Leaves ovate to broad-ovate or rarely reniform (var. _reniformis_ Tidestrom) abruptly short-pointed or acuminate at apex rounded or rarely cuneate at the wide base, closely crenately serrate with glandular teeth, thin, green and lustrous above, dull green or rarely pale below, up to 4½′ long and broad with a prominent midrib, slender primary veins and conspicuous reticulate veinlets; petioles slender, compressed laterally, 1½′—3′ long. Flowers: aments 1½′—2½′ long, the pistillate becoming 4′ in length at maturity; scales deeply divided into 3—5 linear acute lobes fringed with long soft gray hairs; disk oblique, the staminate entire, the pistillate slightly crenate; stamens 6—12; ovary conic, with a short thick style and erect stigmas thickened and club-shaped below and divided into linear diverging lobes. Fruit maturing in May and June, oblong-conic, light green, thin-walled, nearly ¼′ long; seeds obovoid, light brown, about 1/32′ in length.

A tree, 20°—40° high, with a trunk 18′—20′ in diameter, slender remote and often contorted branches somewhat pendulous toward the ends, forming a narrow symmetrical round-topped head, and slender branchlets covered with scattered oblong orange-colored lenticels, bright red-brown and very lustrous during their first season, gradually turning light gray tinged with red, ultimately dark gray, and much roughened for two or three years by the elevated leaf-scars. Winter-buds slightly resinous, conic, acute, often incurved, about ¼′ long, narrower than the more obtuse flower-buds, with 6 or 7 lustrous glabrous red-brown scales scarious on the margins. Bark thin, pale yellow-brown or orange-green, often roughened by horizontal bands of circular wart-like excrescences, frequently marked below the branches by large rows of lunate dark scars. Wood light brown, with nearly white sapwood of 25—30 layers of annual growth.

Distribution. Southern Labrador to the southern shores of Hudson’s Bay and northwesterly to the mouth of the Mackenzie River, through the northern states to the mountains of Pennsylvania, northern Ohio, Indiana and Illinois, eastern and central Iowa and northeastern Missouri; common and generally distributed usually on moist sandy soil and gravelly hillsides; most valuable in the power of its seeds to germinate quickly in soil made infertile by fire and of its seedlings to grow rapidly in exposed situations; westward passing into the var. _aurea_ Daniels, with thicker rhombic to semiorbicular or broad-ovate generally smaller leaves, usually pale on the lower surface, rounded or acute and minutely short-pointed at apex, rounded or cuneate at base, often entire with slightly thickened margins, or occasionally coarsely crenately serrate, with inconspicuous reticulate veinlets, turning bright golden yellow in the autumn before falling.

A tree occasionally 100° high with a trunk up to 3° in diameter, with pale often white bark, becoming near the base of old stems 2′ thick, nearly black, and deeply divided into broad flat ridges broken on the surface into small appressed plate-like scales.

Distribution. Valley of the Yukon River to Saskatchewan, and southward through the mountain ranges of the Rocky Mountain region to southern New Mexico, the San Francisco Mountains of Arizona, and westward to the valley of the Skeena River, British Columbia, western Washington and Oregon, the western slopes of the Sierra Nevada and the high mountains of southern California, and eastward to North and South Dakota and western Nebraska; on the mountains of Chihuahua, and on the Sierra de Laguna, Lower California.

Populus tremuloides var. vancouveriana Sarg.

_Populus vancouveriana Trel._