BETUr.A 



BETULA 



159 



silvery gray or light orange, on old trunks reddish 

 brown ; young bark aromatic, but somewhat bitter : 

 branchlets usually pilose : Ivs. ovate or oblong-ovate, 

 usually rounded at the base, acuminate, sharply and 



231. Cone of Betula lu 



Natural size. 



doubly serrate, usually hairy along the veins beneath : 

 cones like the last, but thicker, and bracts larger, pu- 

 bescent outside. From Newfoundland south to N. Caro- 

 lina and Tenn., west to Minn. S.S. 9:449. Em. 2:15.- 

 One o£ the most valuable forest trees in the northern 

 states, much resembling the former in habit. Var. per- 

 siciidlia, Dipp., has larger and longer Ivs., often ovate- 

 lanceolate. 



rr. Shape of li'S. ovate, broad and usnallij tnineate. 

 sow, iimrs cordate at the base: reins not im- 

 jir<'^sr<l above: long-petioled. 



.S. Ermani, Cham. Tree, 60 ft. : trunk white; branches 

 orange-colored ; branchlets usitally glandular and pu- 

 bescent when young : Ivs. broadly triangular-ovate, 

 acuminate, irregularly coarsely serrate, 2-4 in. long, 

 hairy when unfolding, with 7-10 pairs of veins : cones 

 oblong ; bracts pubescent, with liuear-oldong lobes, 

 middle one somewhat longer. N. E. Asia, Japan.— 

 Handsome round-headed tree, with slender br.anches. 



6. costata, Trautv. Tree, 50 ft. : bark yellowish brown : 

 branches not or slightly glandular : Ivs. ovate, rarely 

 oblocg-ovate, irregularly doubly serrate, with 9-12 pairs 

 of veins, long acuminate, 2-33^ in. long, glabrous : 

 ?ones elliptic ; bracts glabrous, with short, rhombic or 

 obovate lateral lobes. Japan. Manchuria. 



crc. Shape of Jvs. rhombic-ovate , cuneate at the base: 

 veins stightty impressed above: petioles rather 

 short : cones erect, peduncled, cylindrical. 



7. nigra, Linn. (B. rubra, Michx.). Red or River 

 BiKCH. Tree, 50-90 ft.: bark reddi.sh brown, or silvery 

 gray on younger branches, separating into numerous 

 thin, papery flakes ; branchlets pubescent : Ivs. rhom- 

 bic-ovate, acute, doubly serrate, pubescent when young, 

 at length only on the veins beneath, pale or glaucescent 

 beneath, 2-3K in. long : cones 1-1 3li in. long, cylindri- 

 cal, ripening in May or June ; bracts pubescent, with 

 erect, linear-oblong, nearly equal lobes. Froin Mass. 

 south to Fla. and west to Kans. and Minn. S.S. 9: 452. 

 — A moisture-loving, graceful tree, with slender, very 

 numerous branches, and remarkable for its torn and 

 lagged bark. 



AA. I'eins of Ivs. 7 or less, not impressed pairs. 

 B. Wings usually broader than the nut, 



c. Trunk with white bark. Trees; rarely shrubs. 



S. papyrifera, Marsh. (JS.prtpj/cdceo, Ait.). Paper or 

 Canoe Bikch. Fig. 2J2. Tree, 60-80, exceptionally 

 120, ft.: branchlets glandular, hairy when young : Ivs. 

 ovale, narrowed to- cordate at the base, acuminate, 

 coarsely and usually doubly serrate, pubescent on the 

 veins beneath or nearly glabrous, iyi-4%'m. long: 

 cones peduncled, 1-2 in. long ; bracts with short and 

 broad divergent lateral lobes. N. states from the Atlan- 

 tic to Pacific coast. S.S. 9:451. Em. 238. G.F.8:223. 

 — Ornamental tree, with very white trunk and a loose, 

 graceful head when older. Var. cordifolia, Kegel. {B. 

 pyri folia anil p la typhy Ha, Hort.}. Lvs. broadly ovate, 

 usually cordate, large. Var. minor, Tuckerm. Low, 

 busliy tree with smaller lvs. an<l frs. Mts. of N. Eng 

 and X. York. 



9. populifolia, Ait. IB. alba, va,T. populifolia, Spach.). 

 White Birch. Snuill tree, exceptionally 40 ft., -with 

 smooth white bark ; branchlets with numerous resinous 

 glands : lvs. slender, petioled, triangular or deltoid, 

 long acuminate, coarsely doubly serrate, glutinous when 

 young, glabrous at length and shining : cones slender, 

 yt;ilk<Ml. cylindrical, about 1 in. long ; bracts pubescent, 

 tin- lateral lobes divergent, about as long as the middle 

 'III! . From N. Brunswick to Delaware, west to Ontario. 

 S.S.;h4."i0. Em. 1:242. — A small, graceful, but short- 

 livid tree, yet thriving in dry and poor soil. Var. 

 laciniata, Hort. Lvs. incised-laciniate. Var. p^ndula. 

 Hurt. Branches distinctly pendulous. Var. purpxirea, 

 Hort. Lvs. purple when young, gr^en at length. B. 

 populifolia xpapyrifera is shown in G.F. 8: 356. 



10. 41ba, Linn. European White Birch. Fig. 233. 

 Tree, sometimes 80 ft., with white bark : lvs. slender- 

 petioled, ovate or rhombic-ovate, acute or acuminate, 

 doubly serrate : cones erect or pendulous, cylindrical: 

 bracts with horizontally spreading lateral lobes about as 

 long as the middle one. From Eu. to Jap. — This very 

 variable species may be divided into 2 subspecies: 



(1) p6ndula, Roth (B. verrucdsa. Ehrh.). Branches 

 more pendulous, glabrous, usually glandular : lvs. 

 rhombic-ovate, glutinous when young : cones all pen- 

 dulous. The following varieties belong here : Var. 



232. Staminate catkin (natural size) and flowers (enlarged) 

 of Betula papyrifera. 



atropurpurea. Hort. Lvs. dark puiple. Var. Dalec&r- 

 lica, Linn. (i?./(/ri»i()/«, Hort.). Fig. 234. Lvs. more 

 or less deeply lohed with incised-serrate lobes. Var. 

 fastigiita, Hort. (if straisrht, upright, columnar 

 growth. Var. Japbnica, iliq. [B.dlba, vai, Taiischi, 



