SALICACES. SILVA OF NORTH AMERICA. 171 
POPULUS ANGUSTIFOLIA. 
Narrow Leaved Cottonwood. 
LEAvEs lanceolate or ovate-lanceolate, green on both surfaces. 
Populus angustifolia, James, Long’s Exped. i. 497 Populus salicifolia, Rafinesque, Alsograph. Am. 43 
(1823). — Torrey, Ann. Lyc. N. Y. ii. 249; Frémont’s (1838). 
Rep. 97 ; Sitgreaves’ Rep. 172 ; Ives’ Rep. 27. —Nuttall, Populus Canadensis, y angustifolia, Wesmael, De Can- 
Sylva, i. 52, t. 16. — Watson, Am. Jour. Sci. ser. 3, xv. dolle Prodr. xvi. pt. ii. 329 (1868) ; Mém. Soc. Sci. Hai- 
135. — Sargent, Forest Trees N. Am. 10th Census U. 8S. naut, sér. 3, ili. 243 (Monogr. Pop.). 
ix. 174. — Coulter, Man. Rocky Mt. Bot. 339.— Dippel, Populus balsamifera, var. angustifolia, Watson, King’s 
Handb. Laubholzk. ii. 202, £. 97.— Koehne, Deutsche Rep. v. 327 (1871) ; Pl. Wheeler, 17. — Porter, Hayden’s 
Dendr. 83. — Rydberg, Bull. Torrey Bot. Club, xx. 50, Rep. 1871, 494. — Porter & Coulter, Fl. Colorado ; Hay- 
t. 140. den’s Surv. Misc. Pub. No. 4, 129. 
A tree, fifty or sixty feet in height, with a trunk rarely more than eighteen inches in diameter, and 
slender erect branches which form a narrow and usually pyramidal head. The bark of the trunk is 
from three quarters of an inch to an inch in thickness, light yellow-green, divided near the base of old 
trees by shallow fissures into broad flat ridges, and smooth and much thinner on the upper part of the 
trunk, on young stems, and on the branches. The branchlets are slender and marked with pale lenticels, 
glabrous or rarely puberulous and light yellow-green when they first appear, rather bright or, on 
vigorous young shoots, often dark orange-color during their first winter, and pale yellow in their second, 
becoming ashy gray in their third or fourth year. The buds are saturated with fragrant balsamic 
exudations, and are ovate, long-pointed, and covered by about five thin concave scales, chestnut-brown 
on the outer surface and.yellow-green on the inner ; the terminal bud is terete, from one fourth to one 
half of an inch long, and nearly twice as large as the axillary buds, which are often much flattened 
posteriorly by pressure against the stem. The leaves are lanceolate, ovate-lanceolate, or rarely obovate, 
narrowed to the tapering acute or rounded apex, gradually narrowed and wedge-shaped or rounded at 
the base, and finely or, on vigorous shoots, more coarsely serrate with incurved teeth furnished at first 
with small dark glands which often disappear before the end of the season; when they unfold they are 
slightly puberulous on the lower surface, and at maturity are thin and firm, glabrous or rarely puberu- 
lous below, bright yellow-green on the upper surface and rather paler on the lower, from two to three 
inches long and from half an inch to an inch wide or, on vigorous shoots, occasionally six or seven 
inches long and an inch and a half wide, with stout yellow midribs and numerous slender oblique pri- 
mary veins arcuate and often united near the slightly thickened revolute margins, and obscure reticulate 
veinlets; they are borne on slender petioles somewhat flattened on the upper side toward the slightly 
enlarged base, and turn dull yellow in the autumn before falling, when they leave small nearly oval or 
obcordate scars. The stipules of the first leaves resemble the bud-scales in size and shape ; higher 
on the branch they gradually decrease in size, and on the last leaves are ovate or lnear-lanceolate, 
white and scarious, and from half an inch to nearly an inch in length, and usually fall before the 
leaf has grown to its full size. The aments are densely flowered, glabrous, short-stalked, pendulous, 
and from one and a half to two and a half inches long, and appear before the leaves ; their scales are 
glabrous, thin and scarious, light brown, broadly obovate, and deeply and irregularly cut into numerous 
dark red-brown filiform lobes. The stamens, which vary from twelve to twenty in number and consist 
of short filaments and large light red anthers, are inserted in a deep cup-shaped short-stalked slightly 
oblique disk with thickened reflexed margins. The ovary is ovate, more or less two-lobed, crowned 
