BETULACEX. 
SILVA OF NORTH AMERICA. 73 
ALNUS OREGONA. 
Alder. 
LEAVES ovate or elliptical, rusty-pubescent on the lower surface. 
Alnus Oregona, Nuttall, Sylva, i. 28, t. 9 (1842). — New- 
berry, Pacific R. R. Rep. vi. pt. iti. 25, 89. — Cooper, 
Pacific R. R. Rep. xii. pt. ii. 28, 68. 
Alnus rubra, Bongard, Mém. Phys. Math. et Nat. pt. ii. 
Acad. Sci. St. Pétersbourg, ii. 162 (Vég. Sitcha) (not 
Betula-Alnus rubra, Marshall) (1833). — Hooker, Fi. 
Bor.-Am. ii. 158.— Spach, Ann. Sci. Nat. sér. 2, xv. 
205 (Revisio Betulacearum).— Endlicher, Gen. Suppl. 
iv. pt. ii. 21. — Lyall, Jour. Linn. Soc. vii. 134. — Regel, 
Bull. Soc. Nat. Mosc. xxxviii. pt. ii. 429 (Gattungen 
Betula und Alnus); De Candolle Prodr? xvi. pt. ii. 
186. — Torrey, Bot. Wilkes Explor. Exped. 467. — 
Brewer & Watson, Bot. Cal. ii. 80. — Sargent, Forest 
Trees N. Am. 10th Census U. S. ix. 163. — Parry, Bull. 
Cal. Acad. ii. 351. — Mayr, Wald. Nordam. 285, t. 5. — 
Dippel, Handb. Laubholzk. ii. 157, £. 77. — Koehne, 
Deutsche Dendr. 114.— Herder, Act. Hort. Petrop. xii. 
73 (Pl. Radd.). — Greene, Man. Bot. Bay Region, 
298. 
Alnus incana, 7 rubra, Regel, Nouv. Mém. Soc. Nat. Mosc. 
xii. 157, t. 17, £. 3, 4 (Monographia Betulacearum) 
(1860). 
Usually forty or fifty feet high, with a tall straight trunk varying from six inches to two feet in 
diameter, and a narrow pyramidal head of slender somewhat pendulous branches, Alnus rubra, which 
is one of the largest trees of the genus, often attains the height of eighty feet and forms a trunk three 
and a half feet through. The bark of the trunk is rarely more than a quarter of an inch thick, and is 
close, smooth in general appearance but roughened with minute wart-like excrescences, and pale gray 
or nearly white, the thin outer layer in separating displaying the bright inner bark. The branchlets 
are slender and marked with minute scattered pale lenticels, and at first are light green and coated 
with hoary tomentum which does not entirely disappear, especially from their extremities, until the 
second season ; during their first winter they are bright red and lustrous, and then gradually grow 
lighter and ultimately ashy gray. The winter-buds are about one third of an inch long, dark red and 
covered with pale scurfy pubescence. The leaves are ovate or elliptical, acute at the apex, abruptly or 
gradually narrowed and wedge-shaped or rounded at the base, and crenately lobed, the lobes being 
dentate with minute gland-tipped teeth and slightly revolute on the margins; when they unfold they 
are coated with pale tomentum, and at maturity are dark green and glabrous, or pilose with scattered 
white hairs on the upper surface and clothed on the lower with short rusty pubescence, from three to 
five inches long and from an inch and three quarters to three inches broad, or sometimes on vigorous 
branches eight or ten inches in length, with broad midribs and primary veins green and impressed on 
the upper side and orange-colored on the lower, the veins running obliquely to the points of the lobes 
and connected by conspicuous cross slightly reticulate veinlets ; they are borne on orange-colored nearly 
terete slightly grooved petioles from one half to three quarters of an inch in length and fall gradually 
very late in the autumn, or at the south during the winter. The stipules are ovate, acute, pale green 
flushed with red, coated with pale tomentum, and from an eighth to a quarter of an inch long. The 
aments of staminate flowers, which are produced in dark red-stemmed racemes from two to three inches 
in length, first appear at midsummer and are raised on short stout peduncles; during the winter they 
are about an inch and a quarter long and an eighth of an inch thick, and are covered with dark 
red-brown lustrous closely appressed scales, and when they are fully grown and the flowers open in 
very early spring before the unfolding of the leaves, they are from four to six inches in length and a 
quarter of an inch in thickness, with ovate acute orange-colored glabrous scales. The calyx is yellow 
and four-lobed, with ovate rounded lobes rather shorter than the four stamens, which have included 
filaments and yellow anthers. The pistillate aments are produced in short racemes, and are usually 
