BETULACE^. (bIKCH FAMILY.) 4»9 



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

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

 (!'- U' long), the scales with short and divergent lobes. (B. carpinifolia, Ehrh., 

 Michx. ) — Moist woods, &c. : common northward from New England to Illinois, 

 and along the Alleghany region southward. — Rather large tree, reddish-bronze- 

 colored on the spray, much as in the Garden Cherry : timber rose-colored, fine- 

 grained, valuable for cabinet-work. 



2. B. Itltea, Michx. f. (Yellow or Gray Bikcii.) Barh of trunk yel- 

 lowish- or silvery-gray, detaching in very thin filmy layers, within and the twigs 

 much less aromatic ; leaves slightly or not at all heart-shaped and often nar- 

 rowish towards the base, duller-green above and usually more downy on the 

 veins beneath; fruiting catkins oblong-ovoid (V or less in length, 6"-9" thick), 

 the thinner scales (5" -6'' long) twice as large as in No. 1, and with narrower 

 barely spreading lobes. (B. exce'lsa, Amer. authors, but not oi Ait., Regel, &c. 

 The latter unaccountably fiiils to distinguish the present from the preceding 

 species.) — Moist woods, New England to L. Superior and northward. — Wood 

 whiter and less valuable : tree not higher than No. 1. Leaves 3' - 5' long. 



* » Trees, with chalky-white bark of the trunk separable in thin sheets, ovate or tri- 



angular leaves of firmer texture, on long and slender petioles : fruiting catkins 

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

 with short diverging lobes, separating freely from the axis : wing of the fiuit 

 much broader than its body. 



3. B. &lba, var. populif61ia, Spach. (Amebican White Bibch.) 

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

 base, smooth and shining both sides, except the resinous glands when young. (B. 

 populifolia, Ait.) — Common on poor soils, Penn. to Maine, near the coast. — 

 A small and slender graceful tree (15°-25° high), with bark much less separa- 

 ble into sheets than the next ; the mostly very long-pointed leaves on petioles 

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



4. B. papyrioea, Ait. (Paper or Canoe Birch.) JOeaves ovate, taper- 

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

 above, dull underneath. — Woods, New England to Penn. and Wisconsin, almost 

 entirely northward, and extending far northwest. — A large tree, with fine- 

 grained wood, and very tough durable bark splitting freely into paper-like 

 layers. Leaves dark-green above, pale, glandular-dotted, and a little hairy on 

 the veins underneath, sharply and unequally doubly serrate, 3-4 times the 

 length of the petiole. — Var. minor, Tuckerman, in the alpine region of White 

 Mountains, is a dwarf form, approaching the var. occidentalis of N. W. Amer. 

 and B. Davurica. In this country no transitions are seen between our White 

 and the Paper Birch. (The original B. excclsa. Ait., and of Regel, seems likely 

 to belong here, or to have been mixed up with the next. ) 



* # * Tree, with greenish-brown bark, somewhat laminate, and reddish twigs, ovate 



leaves whitish beneath, and soft-downy pedancled fruiting catkins. 



5. B. nigra, L. (River or Red Birch.) Leaves rhombic-ovate, acut- 

 ish at both ends, irregularly doubly serrate, whitish and (until old) downy un- 

 derneath ; petioles and peduncle of nearly the same length (3" -7") and with 



