BETULACK.T':. (niUOn FAAIILY.) 4')9 



and finely doubly serrate all round, wlicn mature shinini;- or hri^lit green above 

 and glabrous except on the veins beneath ; fiuitimj calkins oli/oiif/ci/liiidiicul 

 (I'- l\' long), the scales with short and divergent lobes. (IJ. carpinifolia, Ehr/i., 

 Htlichx.) — Moist woods, &e. : common northward from New England to Illinois, 

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

 eolored on the spray, nuich as in the Garden (Mierry : timber rose-colored, fine- 

 grained, valuable for cabinet-work. 



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

 hvcisli- or silvery-graij, ddiiclung in very thin Jilniy hii/cis, within and the twigs 

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

 rowish towards the base, duller-green al)ove and usually more downy on the 

 veins beneath; fruiting catkins oblong-ocoid (I' or less in length, G"-9" thick), 

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

 b'lreli/ spreading lobes. (B. cxcelsa, Amer. authors, but not of Ait., Kegel, &c. 

 The latter unaccountal)ly fails to distinguish the present froni 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 ckalkif-ichite bark of the Iriinlc separable in thin sheets, ovate or tri- 



angular leaves of ^firmer texture, on long and ."slender petioles : fruiting catLins 

 cylindrical, usually hanging on rather slender peduncles ; their sc(des glabrous, 

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

 much broader than its body. 



3. B. alba, var. populifdlia, Spach. (American White Birch.) 

 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, Pcun. 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. papyr^cea, Ait. (Paper or Canoe Birch.) Daves ovate, taper- 

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

 above, dull underneath. — Woods, New England to Pcnn. 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 undern?ath, 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, ajipronebing the var. occidentalis of N. W. Amer, 

 and B. Da\uriea. In- this country no transitions are seen between our White 

 and the Paper Birch. (The original B. cxcelsa, Ait., and of Kegel, seems likely 

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



* * * Tree, with greenish-brown bark, somewhnt livninnti-, and reddish twiqs, ovate 



li'ures u-hiti.-ih bent-alh, and sofi-downy pediin<-l<d fruiting catkins. 



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

 ifih at both ends, irregularly doiildy serrate, whitish and (until old) downy un- 

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



