BETULA 



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 



BETULA 



159 



331. Cone of Betula lutea. 

 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. 235.— 

 One of 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. 



€0. Shape of Ivs. orate, broad and usually truncate, 

 sometimes cordate at the base: veins not im- 

 pressed above: long-petioled. 



5. Armani, Cham. Tree. 60 ft. : trunk white; branches 

 orange-colored ; branchlets usually 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 linear-oblong lobes, 

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

 Handsome round-headed tree, with slender branches. 



6. oosta,ta, Trautv. Tree, 50 ft.: bark yellowish brown : 

 branches not or slightly glandular : Ivs. ovate, rarely 

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

 of veins, long acuminate, 2-3X ii- louR. glabrous : 

 cones elliptic ; bracts glabrous, with short, rhombic or 

 obovate lateral lobes. Japan. Manchuria. 



CCC. Shape of h'S. rhombic-ovate, ciineate at the base; 

 veins slightly impressed above: petioles rather 

 short: cones erect, pednncled, cylindrieal. 



7. nigra, Linn. {B. rubra, Michs.). Red or River 

 Birch. Tree, 50-90 ft. : bark reddish 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, 2-3J^ in. long : cones 1-1% in. long, cylindri- 

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

 erect, linear-oblong, nearly equal lobes. From 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 

 ragged bark. 



AA. Feins of Ivs. 7 or less, not impressed pairs. 



B. Wings usually broader than the nut. 

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



8. papyrifera, Marsh. (-B.papj/j'dcca, Ait.). Paper or 

 Canoe Bibch. Fig. 232. Tree, 60-80, exceptionally 

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

 ovate, narrowed to cordate at the base, acuminate, 

 coarsely and usually doubly serrate, pubescent on the 

 veins beneath or nearly glabrous, l%-i% in. 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.P. 8:223. 

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

 graceful head when older. Var. cordifdlia, Begel. {B. 

 pyrifdlia and platyph^lla,'Rort.}. Lvs. broadly ovate, 

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

 bushy tree with smaller lvs. and frs. Mts. of N. Eng. 

 and N. York. 



9. populifdlia. Ait. (B. alba, var. populifblia, Spach.). 

 White Birch. Small 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, 

 stalked, cylindrical, about 1 in. long ; bracts pubescent, 

 the lateral lobes divergent, about as long as the middle 

 one. From N. Brunswick to Delaware, west to Ontario. 

 S.S. 9:450. Em. 1:242. -A small, graceful, but short- 

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

 lacini^ta, Hort. Lvs. incised-laciuiate. Var. p^ndula, 

 Hort. Branches distinctly pendulous. Var. purpilTea, 

 Hort. Lvs. purple when young, green at length. B. 

 populifolia xpapyi-ifera 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) pfindula. Roth (B. vernccbsa, 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. 



atropurpiurea. Hort. Lvs. dark purple. Var. Dalecir- 

 lica,, hmn. {B.lacinidta, Hort.). Fig. 234. Lvs. more 

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

 {astigiata, Hort. Of straight, upright, columnar 

 growth. Var. Japbnica, Miq. (B. dlba, var. Taiischi, 



