CUPULIFER.E. ^OAK FAMILY.) 471 



1. BE TULA, Tourn. Birch. 



Sterile flowers 3, and bractlets 2, to each shield-shaped scale or bract of the 

 catkius, consistiDg each of a calyx of one scale bearing 4 short filaments with 

 I-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 oi 

 calyx, each of a naked ovary, becoming a broadly winged and scale-like nutlet 

 (or small samara) crowned with the two spreading stigmas. — Outer bark 

 usually separable in sheets, that of the branchlets dotted. Twigs and leaves 

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

 Sterile catkins long and drooping, terminal and lateral, sessile, formed in sum- 

 mer, remaining naked through tlie succeeding winter, and expanding their 

 golden flowers in early spring, with or preceding the leaves ; fertile catkins 

 oblong or cylindrical, peduncled, usually terminating very short 2-leaved early 

 lateral branches of the season. (The ancient Latin name, of Celtic origin.) 



* Trees, icith brown or yeUow-gray hark, sweet-aromatic as well as the twigs, 



viembranaceous and straight-veined Hornbeam-like leaves heart-shaped or 

 rounded at base, on short petioles, and sessile very thick fruiting catkins ; 

 their scales about equally 3-cleft, rather persistent ; wing of fruit not broader 

 than the seed-bearing body. 



1. B. lenta, L. (Cherry B. Sweet or Black Birch.) Bar^ of trunk 

 dark brown, close (outer layers scarcely laminate), very sweet-aromatic; leaves 

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

 and finely douldy serrate all round, when mature shining or bright green above 

 and glabrous except on the veins beneath ; frtdting catkins oblong -cylindrical 

 (1-1^' long), the scales with short and divergent lobes. — Rich Avoodlands, 

 Newf. to N. Del., ?»ud south in the mountains, west to Minn., and S. Ind. 

 Tree 50-7.5° high, with reddish bronze-colored spray; wood rose-colored, fine- 

 grained, valuable for cabinet-Avork. 



2. B. lutea, Michx. f. (Yellow or Gray Birch.) Bark of trunk yel- 

 lowish- or silvery-gray, detaching in very thin filmy /a yers, Avithin and the twigs 

 much less aromatic ; leaves (3 - 5' long) slightly or not at all heart-shaped and 

 often narrowish toward the base, duller-green above and usually more downy 

 on the veins beneath ; fruiting catkins oblong-ovoid (T or less in length, 6-9" 

 thick), the thinner scales (5-6" long) twice as large as in n. 1, and with nar- 

 rower barely spreading lobes. — Rich moist woodlands, Canada and N. Eng. to 

 Del., west to Minn. ; also along high peaks to Tenn. and N. C. Often 60-90^ 

 high at the north ; wood wliiter and less valuable. 



* * Trees, with chalky-white bark separable in thin sheets, ovate or trianqular 



leaves of firmer texture, on long slender petioles ; fruiting catkins cylindrical, 

 usually hanging on rather slender peduncles ; their scales glabrous, ivith 

 short diverging lobes, freely deciduous ; wing of the fruit much broader than 

 its body. 



3. B. populif61ia, Ait. (American White Birch. Gray Birch.) 



Trunk usually ascending (1 5 - 30° high) ; leaves triangular (deltoid), very taper- 

 pointed (usually aljruptly), truncate or nearly so at the broad base, smooth and 

 shining both sides, except the resinous glands when young. (B. alba, var. 



