BETULA 



BET U LA 



159 



silvery gray or light orange, on old trunks reddish 

 brown : young bark aromatic, but somewhat bitter : 

 branch let's usually pilose : Ivs. ovate or oblong-ovate, 

 usually rounded at the base, acuminate, sharply and 



231. 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- 

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

 lanceolate. 



cc. Shape of Ivs. ovate, broad and usually truncate, 

 sometimes cordate at the base: veins not im- 

 pressed above: long -pet loled. 



5. Armani, Cham. Tree. 60ft.: 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. E. Asia, Japan. 

 Handsome round-headed tree, with slender branches. 



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

 branches not or slightly glandular : Ivs. ovate, rarely 

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

 of veins, long acuminate, 2-3j^ in. long, glabrous : 

 cones elliptic ; bracts glabrous, with short, rhombic or 

 obovate lateral lobes. Japan. Manchuria. 



ccc. Shape of Ivs. rhombic -ovate, cuneate at the base; 

 veins slightly impressed above: petioles rather 

 short : cones erect, peduncled, cylindrical. 



1. nigra, Linn. (B. riibra, Michx.). 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, 2-3 K 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 

 fagged bark. 



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



B. Wings usually broader than the nut. 

 c. Trunk with white bark. Trees ; rarely shrub*. 



8. papyrifera, Marsh. (B. papyracea, Ait.). PAPER or 

 CANOE BIRCH. Fig. 232. Tree, 00-80, 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%-4% 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.F.8:223. 

 Ornamental tree, with very white trunk and a loose, 

 graceful head when older. Var. cordifolia, Regel. (B. 

 pyrifblia &n(l platyphylla,H.ort.). Lvs. broadly ovate, 

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

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

 and N. York. 



9. populifdlia, Ait. (B. dlba, v&r.populi folia, Spach.). 

 WHITE BIRCH. Small tree, exceptionally 40 ft., with 

 smooth white bark ; branchlets with numerous resinous 

 glands : Ivs. 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. 

 laciniata, Hort. Lvs. incised-laciniate. Var. pendula, 

 Hort. Branches distinctly pendulous. Var. purpurea^ 

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

 populifoliaxpapyrifera is shown in G.F. 8: 356. 



10. dlba, Linn. EUROPEAN WHITE BIRCH. Fig. 233. 

 Tree, sometimes 80 ft., with white bark : Ivs. 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) pSndula, Roth (B. verrucdsa, Ehrh.). Branches 

 more pendulous, glabrous, usually glandular : Ivs. 

 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 purple. Var. Dalecar- 

 lica, Linn. (B.laclniata, Hort.). Fig. 234. Lvs. more 

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

 fastigiata, Hort. Of straight, upright, columnar 

 growth. Var. Japdnica, Miq." (B. dlba, var. Tauschi, 



