BETULACE^E. (BIRCH FAMILY.) 411 



leaves often spicy-aromatic. Foliage mostly thin and light. Buds sessile, scaly 

 Sterile catkins long and drooping, terminal and lateral, formed in summer, re- 

 maining naked through the succeeding winter, and expanding their golden 

 flowers in early spring, preceding the leaves : fertile catkins oblong or cylindri- 

 cal, lateral, protected by scales through the winter, and developed with the 

 leaves. (The ancient Latin name.) 



* Trees , with the bark of the trunk white externally, separable in thin sheets .* petioles 



slender : fertile catkins cylindrical, peduncled, spreading or drooping. 



1. B. alba, var. populifolia, Spach. (AMERICAN WHITE BIRCH.) 

 Leaves triangular (deltoid), very taper-pointed, truncate or nearly so at the broad 

 base, smooth and shining both sides (glandular-dotted when young). (B. populi- 

 folia, Ait.) Common on poor soils, Penn. to Maine, near the coast. A small 

 and slender, very graceful tree, with chalky-white bark, much less separable 

 into sheets than the next species ; the very long-pointed leaves on- petioles of 

 fully half their length, tremulous as those of an Aspen. (Eu.) 



2. B. papyracea, Ait. (PAPER BIRCH. CANOE BIRCH.) Leaves 

 ovate, taper-pointed, heart-shaped or abrupt (or rarely wedge-shaped) at the base, 

 smooth above, dull underneath ; lateral lobes of the fruit-bearing bracts short and 

 rounded. Woods, New England to Wisconsin, almost entirely northward, and 

 extending far north. A large tree, with fine-grained wood, and very tough 

 durable bark splitting into paper-like layers. Leaves dark-green above, pale, 

 glandular-dotted, and a little hairy on the veins underneath, sharply and une- 

 qually doubly serrate, 3-4 times the length of the petiole. There is a dwarf 

 mountain variety. 



* * Trees, with reddish-brown or yellowish bark : petioles short : fertile catkins ovoid- 



oblong, scarcely peduncled. 



3. B. nigra, L. (RIVER or RED BIRCH.) Leaves rhombic-ovate, acutish 

 at both ends, whitish and (until old) downy underneath ; fertile catkins oblong, 

 somewhat peduncled, woolly ; the bracts with oblong-linear nearly equal lobes. 

 (B. rubra, Michx. f.) Low river-banks, Massachusetts to Virginia and south- 

 ward. A rather large tree, with reddish-brown bark and compact light-colored 

 wood : leaves somewhat Alder-like, glandular-dotted, sharply doubly serrate. 



4. B. excelsa, Ait. (YELLOW BIRCH.) Leaves ovate or elliptical, point- 

 ed, narrowed (but mostly heart-shaped) at the base, smoothish, unequally serrate 

 with coarse and very sharp teeth ; fruiting catkins ovoid-oblong, slightly hairy ; lobes 

 of the scales nearly equal, acute, slightly diverging. Moist woods, New England 

 to Lake Superior, and northward. Tree 40 - 60 high, with yellowish silvery 

 bark, thin leaves : twigs less aromatic than in the next ; the wood less valuable. 



5. B. lenta, L. (CHERRY BIRCH. SWEET or BLACK BIRCH.) Leaves 

 heart-ovate, pointed, sharply and finely doubly serrate, hairy on the veins beneath ; 

 fruiting catkins elliptical, thick, somewhat hairy ; lobes of the veiny scales nearly 

 equal, obtuse, diverging. Moist rich woods, New England to Ohio and north- 

 ward, and southward in the mountains. A rather large tree, with dark chest- 

 nut-brown bark, reddish bronze-colored on the spray, much like that of the 

 Garden Cherry, which the leaves also somewhat resemble ; the twigs and foliage 

 spicy-aromatic : timber rose-colored, fine-grained, valuable for cabinet-work. 



