SALICACEZ. SILVA OF NORTH AMERICA. 175 
POPULUS TRICHOCARPA. 
Black Cottonwood. Balsam Cottonwood. 
LEAvsS usually broadly ovate, acuminate, rounded or cordate at the broad base, 
dark green on the upper surface, pale, ferrugineous or silvery on the lower. Ovaries 
tomentose. 
Populus trichocarpa, Hooker, Icon. ix. t. 878 (1852).— Populus angustifolia, Newberry, Pacific R. R. Rep. vi. 
Walpers, Ann. v. 767.— Wesmael, De Candolle Prodr. pt. iii. 89 (not James) (1857). — Cooper, Pacific R. R. 
Xvi. pt. ii. 330; Mém. Soc. Sci. Hainaut, sér. 3, iii. 249 Rep. xii. pt. ii. 29, 68.— Torrey, Bot. Wilkes Explor. 
(Monogr. Pop.).— Watson, King’s Rep. v. 328; Am. Exped. 468. 
Jour. Sci. ser. 3, xv. 136. — Torrey, Bot. Wilkes Explor. Populus balsamifera, Lyall, Jour. Linn. Soc. vii. 134 (not 
Exped. 469. — Brewer & Watson, Bot. Cal. ii. 91. — Sar- Linneus) (1864).— Hall, Bot. Gazette, ii. 93. 
gent, Horest Trees N. Am. 10th Census U. S. ix. 174.— Populus balsamifera, var. (?) Californica, Watson, Am. 
Dippel, Handb. Laubholzk. ii. 210, £. 104. — Koehne, Jour. Sci. ser. 3, xv. 135 (1878). 
Deutsche Dendr. 85. — Coville, Contrib. U. S. Nat. Populus trichocarpa, var. cupulata, Watson, Am. Jour. 
Herb. iv. 200 (Bot. Death Valley Exped.). — Greene, Sci. ser. 3, xv. 136 (1878). — Brewer & Watson, Bot. 
Man. Bot. Bay Region, 300. Cal. ii. 91. 
Populus balsamifera, y, Hooker, Fl. Bor.-Am. ii. 154 (1839). 
A tree, often nearly two hundred feet in height, with a trunk seven or eight feet in diameter, stout 
upright branches, and a broad open head ; or toward the eastern and southern limits of its range much 
smaller. The bark of the trunk is from one and a half to two and a half inches in thickness, ashy gray, 
and deeply divided into broad rounded ridges broken on the surface into thick closely appressed scales. 
The branchlets are stout, terete or slightly angled while young, and marked with numerous orange- 
colored lenticels, and when they first appear are coated with deciduous rufous or pale pubescence ; they 
are light or dark orange-color and lustrous during their first year, and then gradually grow dark gray 
and become much roughened by the greatly enlarged and thickened elevated lunate leaf-scars. The 
winter-buds are resinous and fragrant, ovate, long-pointed, frequently curved above the middle, and 
often flattened by pressure against the stem; they are about three quarters of an inch long and a 
quarter of an inch broad, and are covered by six or seven light orange-brown scales thin and scarious 
on the margins and slightly puberulous on the outer surface, especially at the base of the bud. The 
leaves are broadly ovate or occasionally oblong-rhombic, gradually narrowed and usually short-pointed 
or rarely acute at the apex, broad, rounded, or slightly cordate, or occasionally gradually narrowed and 
wedge-shaped at the base, and finely crenately serrate with minute incurved gland-tipped teeth ; when 
they unfold they are coated with rufous or pale pubescence which is thicker above than below, and at 
maturity are thick and firm in texture, dark rich green and lustrous on the upper surface, pale and rusty 
or silvery white and conspicuously reticulate-venulose on the lower surface, glabrous, with the exception 
of the upper side of the stout ribs and veins, which is usually covered with a fine short pubescence that 
occasionally extends also over the whole upper surface of the leaf, from three to four inches long and 
from an inch and a half to three inches broad; they are borne on slender terete puberulous petioles 
from one to two inches in length, and turn yellow or brown late in the autumn before falling. The 
stipules of the first leaves resemble the inner bud-scales in size and shape, but higher on the branch 
they gradually become smaller, and those of the last leaves are linear-lanceolate, white and scarious, and 
about half an inch long. The flower aments, which appear in February at the south and in early 
spring at the north, are pedunculate and pendulous; the staminate are densely flowered, from an inch 
