﻿Trees of New York State 169 



BETULACEAE 



Betula alba, var. papyrifera (Marsh.) Spach. [Betiila papyrifera Marsh.]* 



Paper Birch, Canoe Birch, White Birch 



Habit — A tree at maturity usually 50-75 feet in height with a trunk diame- 

 ter of 1-2 feet, under optimum conditions sometimes 120 feet tall. Crown 

 in young trees extending nearly to the ground, narrowly pyramidal, con- 

 sisting of short, slender, spreading branches. In mature or crowded trees, 

 the bole is clean below and supports a rather narrow, round-topped, open 

 head with pendulous branches. 



Leaves — Alternate, ovate, acuminate at the apex, rounded or cuneate at the 

 base, coarsely doubly serrate, 2-3 inches long, l%-2 inches wide, at ma- 

 turity thick and firm in texture, dull dark green and usually eglandula? 

 above, pale yellowish green, glabrous or somewhat hairy and marked with 

 minute black glands beneath, borne on stout, yellow, black-glandular 

 petioles. Stipules fugacious. 



Flowers — Appearing in April and May with the leaves, monoecious, borne in 

 aments. Stamuiate aments preformed the preceding season, usually in 

 group of 2-3, subterminal, cylindrical, at anthesis brownish yellow, 3io-4 

 inches long. Pistillate aments appearing as the buds unfold, terminal and 

 solitary on short, 2-leaved lateral branches, pale green, linear-cylindrical, 

 pedunculate, 1-1^ inches long. Flowers borne in clusters of 3. The 

 staminate flowers consist of 4 yellow half-anthers raised on short bifur- 

 cated filaments and accompanied by a calyx of 1 sepal, the cluster of 3 

 covered distally by a peltate, broadly obovate bract and 2 bracteoles. Pis- 

 tillate flowers consisting of a small, green, ovoid ovary crowned by 2 

 spreading, filiform, bright red styles, the clusters of 3 subtended by an 

 oblong, obtuse bract and 2 bracteoles. 



Fruit — A pedunculate, drooping, pale brown, cylindrical, obtuse, woody stro- 

 bile, about 1^2 inches long and % of an inch thick, consisting of puberu- 

 lous or glabrous, imbricated, 3-lobed bracts subtending winged nutlets, 

 both deciduous in the autumn from the slender rachis. Nutlets com- 

 pressed, elliptical to oval, chestnut-browna, about 1/16 of an inch long, 

 with marginal wings broader than the nut. 



Winter characters — Twigs rather stout, lenticellate, smooth, dull reddish 

 brown, at length orange-brown and lustrous, finally white from the exfoli- 

 ation of the outer bark. Buds ovate, acute, smooth, divergent, chestnut- 

 brown, covered by 3-5 scales downy at the margins. Staminate strobiles 

 in groups of 2-3, subterminal, cylindrical, %-l^ inches long. Bark on 

 the trunk and older branches chalky to creamy-white, peeling off in thin 

 papery layers, marked by elongated, horizontal lenticels. Mature bark at 

 the base of mature trunks bro^vnish black, sharply and irregularly fur- 

 rowed. 



Habitat — Thrives on moist sites about lakes, streams, swamps, wooded moun- 

 tain slopes and hillsides, usually intermingled with other hardwoods, more 

 rarely with conifers. 



Range — A transcontinental species ranging from Newfoundland to Alaska, 

 south through New England to central Pennsylvania, Michigan, "Wiscon- 

 sin, Colorado and Washington. Zones C, D, and E. 



Uses — ^Wood light, strong, hard, close-grained, light reddish brown with 

 thick, nearly white sapwood. Largely used in the manufacture of spools, 

 Ukewise woodenware, shoe-lasts, wood-pulp and fuel. The papery bark is 

 made into canoes and souvenirs. The tree is grown ornamentally in the 

 northern states, replacing in many places the European White Birch 

 destroyed by the Bronze Birch Borer. 



*A variety of paper birch, Betula alba, var. cordifoUa (Regel) Fernald, is found 

 at Uigber elevations on cool mountain slopes in tbe Adirondacks and Catskills. 



