BETULACE&. SILVA OF NORTH AMERICA. 69 
BETULA OCCIDENTALIS. 
Black Birch. 
STROBILES oblong, long-stalked, erect or hanging. Leaves broadly ovate, wedge- 
shaped or rounded at the base. 
Betula occidentalis, Hooker, Fl. Bor.-Am. ii. 155 (1839).— t. 35; Pl. Wheeler, 17. — Rothrock, Wheeler's Rep. vi. 
Spach, Ann. Sci. Nat. sér. 2, xv. 197 (Revisio Betulacea- 239.— Brewer & Watson, Bot. Cal. ii. 79. — Sargent, 
rum). — Nuttall, Sylva, i. 22, t. 7. —Endlicher, Gen. Forest Trees N. Am. 10th Census U. S. ix. 160. — Dippel, 
Suppl. iv. pt. ii. 20. — Torrey, Frémont’s Rep. 97; Bot. Handb. Laubholzk. ii. 176. — Koehne, Deutsche Dendr. 
Wilkes Explor. Exped. 466. — Dietrich, Syn. v. 304.— 110. 
Newberry, Pacific R. R. Rep. vi. pt. iii. 89. Cooper, Am. Betula alba, subsp. 5. occidentalis, a typica, Regel, Bull. 
Nat. iii. 408. — Regel, Nouv. Mém. Soc. Nat. Mose. xiii. Soc. Nat. Mose. xxxviii. pt. ii. 400, t. 7, f. 1-5 (Gattun- 
131, t. 15, £. 35 (Monographia Betulacearum). — Porter, gen Betula und Alnus) (1865) ; De Candolle Prodr. xvi. 
Hayden’s Rep. 1871, 493. — Watson, King’s Rep. v. 323, pt. ii. 165. 
A tree, occasionally from thirty to forty feet in height, with a trunk from twelve to eighteen inches 
in diameter, and slender spreading graceful pendulous branches which form an open feathery head ; or 
more commonly with many thin spreading stems springing up from the ground in open clusters fifteen 
or twenty feet high or often much lower, and frequently crowded into nearly impenetrable thickets. 
The bark of the trunk is about a quarter of an inch thick, dark bronze-color, very lustrous, and marked 
with pale brown longitudinal lenticels, which on old trunks are often from six to eight inches long 
and a quarter of an inch wide. The branchlets are slender at first, light green and much roughened 
with large lustrous resinous glands which do not disappear until their second season ; they soon turn 
a dark orange-color, and during their first winter are rather bright red-brown, becoming in the 
following summer dark reddish brown or bronze-color and very lustrous, and are marked with con- 
spicuous pale lenticels which gradually lengthen as the branches increase in size. The buds are ovate or 
slightly obovate, acute, about a quarter of an inch long, and covered with resin ; they are bright green 
and lustrous at midsummer, when they are fully grown, and during the winter are light chestnut-brown. 
The leaves are broadly ovate, acute at the apex, sharply and often doubly serrate with spreading or 
incurved stout glandular mucronate teeth, and sometimes slightly laciniately lobed except at the 
rounded abruptly wedge-shaped truncate or subcordate and often somewhat unequal base; when they 
unfold they are pale green, pilose on the lower surface with a few long pale hairs, and covered with 
conspicuous resinous glands, and at maturity they are thin and firm in texture, above dark dull green 
and sometimes marked until late in the summer with the remnants of the glands, below pale yellow- 
green, rather lustrous, and covered with minute glandular dots, from one to two inches long and from 
three quarters of an inch to an inch wide, with slender pale midribs and remote primary veins coated 
with minute dark glands, and rather conspicuous reticulate veinlets; they are borne on stout puberu- 
lous light yellow and glandular dotted petioles flattened on the upper side, often flushed with red, 
and from one third to nearly one half of an inch long, and turn a dull yellow in the autumn before 
falling. The stipules are broadly ovate, acute or rounded at the apex, slightly ciliate on the margins, 
and bright green at first but soon becoming pale and scarious. During the winter the clustered 
staminate aments are from one half to three quarters of an inch long and about a sixteenth of an 
inch thick, with ovate acute light chestnut-brown lustrous scales pale and slightly ciliate on the margins, 
and when they are fully grown and the flowers open in spring they are from two to two and a half 
inches long and about an eighth of an inch thick, with apiculate scales dark red-brown above the 
