56 KEY AND FLORA 
1. C. caroliniana Walt. Hornseam. A small tree with smooth 
and close gray bark; twigs slender. Leaves ovate-oblong, acute or 
taper-pointed, sharply and doubly serrate, the straight veins termi- 
nating in the larger serrations; downy when young and soon be- 
coming smooth. Staminate catkins 1-1} in. long. Pistillate catkins 
long-peduncled, 8-12-flowered ; bractlets becoming nearly 1 in. long, 
cut-toothed, the middle tooth much longer than the others. In rich, 
moist woods. Often known as “blue beech” and “ ironwood.” * 
IV. BETULA L. 
Trees with slender, aromatic twigs, and thin, usually straight- 
veined leaves. Staminate catkins drooping, flowers usually 3 
in the axil of each bract; stamens 4, short; anthers 1-celled. 
Pistillate catkins erect, flowers 2 or 3 in the axil of each bract; 
ovary sessile, 2-celled; styles 2; bracts 3-lobed ; perianth none. 
Nut broadly winged.* 
1. B. lenta L. CuErry Biren. Leaves ovate or oblong-ovate, 
acute, heart-shaped, finely and doubly serrate, silky when young; 
petioles about } in. long. Staminate catkins clustered, 3-4 in. long. 
Pistillate catkins sessile, about 1 in. long; cylindrical bracts spread- 
ing, acute, smooth. River banks, especially N. A large tree, with 
aromatic twigs. The oil contained in the bark and twigs is distilled 
and used as a substitute for wintergreen.* 
2. B. lutea Michx.f. YELLow Brrou. A large forest tree, some- 
times 60-90 ft. high, with yellowish or silver-gray bark, which peels 
off in extremely thin layers. Leaves ovate or nearly so, usually taper- 
pointed, rounded or sometimes almost heart-shaped at the base, 
sharply and finely serrate, somewhat downy on the veins beneath, 
3-5 in. long. Staminate catkins 3-3} in. long; pistillate catkins 
about 2 in. long. Rich woods N., also southward in the mountains. 
3. B. nigra L. River Bircu, Rep Bircu. A medium-sized tree 
with reddish-brown bark. Leaves rhombic-ovate, acute at the apex, 
acute or obtuse at the base, sharply and doubly serrate, white-downy 
below, becoming smoother with age, petioles short. Staminate catkins 
2-8 in. long. Pistillate catkins 1-1} in. long, peduncles short, bracts 
nearly equally 3-cleft, woolly. River banks, especially S. and W.* 
4. B. populifolia Marsh. Gray Biron. A tall shrub or slender, 
straggling tree, 15-30 ft. high, seldom growing erect, often several 
trunks springing from the ground almost in contact and slanting 
away from each other. Leaves triangular, with a long taper point 
and truncate base, unevenly twice serrate, with rather long, slender 
petioles, which allow the leaves to quiver like those of the aspen. 
