334 BETULACEAE (BIRCH FAMILY) 



of the branches of the preceding year ; the fertile single, terminating short leafy 

 shoots of the season. (The classical name.) 



1. 0. virginiana (Mill.) K. Koch. (AMERICAN HOP H., LEVERWOOD.) 

 Leaves oblong-ovate, taper-pointed, very sharply double-serrate, downy beneath, 

 with 11-15 principal veins ; buds acute ; involucral sacs bristly-hairy at the 

 base. (0. virginica Willd.) Rich woods, N. S. to Man., Minn., Neb., and 

 southw. 



3. CARPINUS [Tourn.] L. HORNBEAM. IRONWOOD 



Sterile flowers similar to those of Ostrya. Fertile flowers several, spiked in 

 a sort of loose terminal catkin, with small deciduous bracts, each subtending a 

 pair of flowers ; the single involucre-like bract open, enlarged in fruit and foli- 

 aceous, merely subtending the small ovate several-nerved nut. Trees or tall 

 shrubs, with close gray bark, in this and in the slender buds and straight-veined 

 leaves resembling the Beech ; leaf-buds and inflorescence as in Ostrya. (The 

 early Latin name.) 



\. C. caroliniana Walt. (AMERICAN H. ; BLUE or WATER BEECH.) Leaves 

 ovate-oblong, pointed, sharply double-serrate, soon nearly smooth ; bractlets 

 3-lobed, halberd-shaped, sparingly cut-toothed on one side, acute. Along 

 streams, N. S. to w. Ont. , and southw. 



4. BETULA [Tourn.] L. BIRCH 



Sterile flowers 3 (the bractlets 2) to each shield-shaped scale or bract of the cat- 

 kins, consisting each of a calyx of one scale bearing 4 short filaments with 1 -celled 

 anthers (or strictly of two 2-parted filaments, each division bearing an anther- 

 cell). Fertile flowers 2 or 3 to each 3-lobed bract, without bractlets or calyx, 

 each a naked ovary, becoming a winged and scale-like nutlet (or small samara) 

 crowned with the two spreading stigmas. Outer bark often separable in sheets, 

 that of the branchlets dotted. Buds sessile, scaly. Sterile catkins terminal and 

 lateral, sessile, formed in summer, remaining naked through winter, and expand- 

 ing in early spring, with or preceding the leaves ; fertile catkins ovoid to cylin- 

 drical, usually terminating very short 2-leaved early lateral branches of the season. 

 (The ancient Latin name. ) 



* Trees or shrubs ; the leaves with the 8 or more pairs of nerves impressed 

 above; fruiting catkins thick (1 cm. or more), short-cylindric to ovoid, their 

 scales rather persistent ; wing of fruit not broader than the seed-bearing body. 



- Bark and twigs sweet-aromatic ; leaves membranaceous, ovate to oblong-ovate, 

 with rounded or cordate bases, regularly serrate, green both sides / fertile 

 catkins sessile, erect. 



1. B. 16nta L. (CHERRY, SWEET, or BLACK B.) Bark of trunk dark brown, 

 close, in age becoming ashy-brown and furrowed, very sweet-aromatic ; leaves 

 ovate or ovate-oblong from a more or less heart-shaped base, acuminate, sharply 

 and finely double-serrate, when mature bright green above and glabrous except 

 on the veins beneath ; fruiting catkins short-cylindric (1.5-2.5 cm. long) ; the 

 scales firm and smooth, with short and divergent lobes. Rich woods, Nfd. to 

 Ont. , s. to Del. , Ind. and centr. la. ; also along the mts. to Fla. and Tenn. 



2. B. lutea Michx. f. (YELLOW or GRAY B.) Bark of trunk yellowish- or 

 silvery-gray, detaching in very thin filmy layers, less aromatic ; leaves slightly or 

 not at all heart-shaped and often narrowed toward the base, duller green above 

 and usually more downy on the veins beneath ; fruiting catkins narrow-ovoid 

 to subglobose, the more foliaceous scales mostly longer, pubescent and with nar- 

 rower barely spreading ciliate lobes. Rich moist woods, Nfd. to Man., s. to Del., 

 111., and Minn. ; also along the mts. to Tenn. and N. C. Trees. with character- 

 istics somewhat intermediate between this and B. lenta have been called B. 

 alleghaniensis Britton. 



t- - Bark not aromatic; leaves firm, rhombic-ovate, cuneate to subtruncate at 

 base, irregularly dentate-serrate, whitish beneath ; fertile catkins pedunded, 

 soft-downy. 



