BETULACE, 
SILVA OF NORTH AMERICA. 79 
ALNUS ACUMINATA. 
Alder. 
Leaves oblong-lanceolate, acute, pale and sometimes puberulous on the lower 
surface. 
Alnus acuminata, Humboldt, Bonpland & Kunth, Nov. 
Gen. et Spec. ii. 20 (1817). — Kunth, Syn. Pl. Aquin. 
i. 863. — Spach, Ann. Sci. Nat. sér. 2, xv. 204 (Revisio 
Alnus acuminata, a genuina, Regel, Nouv. Mém. Soe. 
Nat. Mosc. xiii. 147 (Monographia Betulacearum) (1860) ; 
Bull. Soc. Nat. Mosc. xxxviii. pt. ii. 424 (Gattungen 
Betula und Alnus) ; De Candolle Prodr. xvi. pt. ii. 184. 
Alnus serrulata, y oblongifolia, Regel, De Candolle 
Prodr. xvi. pt. ii. 188 (1868). 
Alnus rhombifolia, Parry, Bull. Cal. Acad. ii. 351 (in 
part) (not Nuttall) (1887). 
? Alnus Jorullensis, var. acuminata, Otto Kuntze, Rev. 
Gen. Pl. ii. 638 (1891). 
Betulacearum). 
Alnus oblongifolia, Torrey, Bot. Mex. Bound. Surv. 204 
(1859). — Watson, Pl. Wheeler, 17.— Rothrock, Wheeler’s 
Rep. vi. 239. — Brewer & Watson, Bot. Cal. ii. 80 (in 
part). — Rusby, Bull. Torrey Bot. Club, ix. 79. — Sar- 
gent, Forest Trees N. Am. 10th Census U. S. ix. 163 (in 
part). — Mayr, Wald. Nordam. 286. 
In the United States a tree, rarely more than twenty or thirty feet in height, with a trunk sometimes 
eight or ten inches in diameter, and long slender spreading branches which form an open round-topped 
head. The bark of the trunk is thin, smooth, and light brown tinged with red. The branchlets are 
slender, slightly puberulous while young, and during their first winter light orange-red and lustrous, and 
marked with small conspicuous pale lenticels; in their second year they are dark red-brown or gray 
tinged with red, and much roughened by the elevated leaf-scars. The buds are acute, bright red, 
lustrous, glabrous, and half an inch in length. The leaves are oblong-lanceolate and acute or rarely 
obovate and rounded at the apex, gradually narrowed and wedge-shaped at the base, sharply and usually 
doubly serrate with small spreading glandular teeth, more or less thickly covered, especially early in the 
season, with minute black glands, dark yellow-green and glabrous, or very slightly puberulous on the 
upper surface, and on the lower surface pale and glabrous, or puberulous, especially along the slender 
yellow midribs and veins, and furnished with small tufts of rusty hairs in the axils of the primary veins ; 
they are from two to three inches long and about an inch and a half wide, and, borne on slender yellow 
pubescent grooved petioles three quarters of an inch long, fall im the late autumn or early winter. 
The stipules are ovate-lanceolate, brown and scarious, and about a quarter of an inch in length. The 
aments of staminate flowers are produced in short stout-stemmed racemes, and during the winter are light 
yellow, from one half to three quarters of an inch in length and about a sixteenth of an inch thick ; they 
are fully grown when the flowers open at the end of February or early in March before the appearance 
of the leaves, and are then from two to two and a half inches long, with ovate pointed dark orange- 
brown scales. The flowers contain usually three, but occasionally two stamens with anthers which are 
pale red when they first appear, but soon turn light yellow. The pistillate aments, which are naked 
during the winter, are from an eighth to nearly a quarter of an inch long when the bright red stigmas 
protrude from between the light brown ovate rounded scales. The strobiles vary from half an inch to 
nearly an inch in length, with thin scales slightly thickened and nearly truncate at the apex. The nut 
is broadly ovate, with a narrow membranaceous border. 
Within the territory of the United States, where it was found in 1851 by Charles Wright,’ the 
botanist of the Mexican Boundary Survey, on the banks of the Mimbres River, Alnus acuminata 
inhabits only the canons of the mountains of southern New Mexico and Arizona, growing, at elevations 
1 See i. 94. 
