Obdbb 120.— BBTUIiAOBiE. 649 



diameter of 2 to 3f. The trunk 13 invested with a dark brown or reddish bark, 

 which becomes rough in old trees, and is remarkable for its agreeably aromatic 

 fragrance and flavor. Leaves 3 — 4' long, about J as wide. Sterile aments 2 — 3' 

 long, fertile much shorter and thicker. In spring the cambium affords the boys a 

 delicious morsel Wood reddish, strong, compact. Apr., May. 



3 B. nigra Ait. Red Birch. Ims. rhomMc-ovate, acute at each end, doubly ser- 

 rate, or obscurely 9 to 13-loied, glaucous beneath ; fertile ament sessile, erect, ovoid, 

 scales villous, the segments linear, equal. — A tree 30 to 50f high, growing on 

 banks of streams and in river swamps, Mass., 111. and Fla. (!) Trunk covered 

 with a reddish or chocolate-colored bark which at length becomes very loose and 

 torn, hanging iu shreds, and finally rough like that of the black cherry. Branches 

 arched and slender ; branchlets almost filiform, often clothing the trunk to the 

 base. Lvs. dark green above, about 3' by 2' often smaller, petioles 6 to 8" long, 

 pubescent. May. (B. rubra Mx.) 



4 B. populifolia Ait. Poplar-leaved Biboh. "White Birch. (Fig. 106.) Lvs. 

 deltoid, long-acwminate, unequally serrate or obscurely many-lobed, very smooth, on 

 smooth petioles ; fertile aments pedunculate ; scales with roundish, lateral lobes. 

 — Like the next, distinguished for the white cuticle with which the trunk is in- 

 vested. It is common in the rocky and mountainous woods of N. Eng., where it 

 seldom exceeds 30 to iOf in height. The branches are covered with a reddish- 

 brown bark, very slender, and throw out in May, long, pendulous aments. 



5 B. papyraoea Ait. Paper Birch. Canoe Birch. Lvs. ovate, acuminate, 

 doubly serrate, the veins hairy beneath; futile aments nodding, pedunculate; 

 lateral lobes of the calyx short, roundish. — This birch is abundant in the hillside 

 woods of N. Eng. to Wis. and Can. It sometimes attains tho height of 60 — '7 Of, 

 but is generally smaller. Trunk 1 — 2f diam., covered with .a tough cuticle con- 

 sisting of numerous laminae, the outer of which is snow white. Of this the In- 

 dians construct their light canoes. Branches dark brown. Leaves 2 — 3' long, J 

 as wide. Sterile aments 1 — 2' long. The wood is of a fine, compact texture, 

 easily wrought. May, Jn. 



IS. mIn'OR. Lvs. smaller, ovate, glabrous, acute, some of thein roundish-obtuse. 

 —White Mts. Shrubs 6— 9f high. 



6 B. pilmila L. DwAHF Birch. Shrub erect, its ascending branches glandular- 

 punctate, glabrous; lvs. obovate, entire at base, obtusely serrate, glabrous; fertile 

 ament cylindrical, about as long as the leaves ; scales half Z-cleft, lobes ovato- 

 oblong, middle one rather longest ; rmt orbicular, conspicuously margi'^d. — A 

 beautiful shrub inhabiting tho mountainous districts of N. and N. W. States, N. 

 to Hudson's Bay. Height 2 to 6C Lvs. about 9'' by 6 or 7", very regularly 

 toothed. Aments of both kinds 1 to 9" (B. glandulosa Mx.) 



7. B nana L. Tiny Birch. Shrub, low, trailing, smooth ; lvs. orbicular, crenatc, 

 reticulated beneath ; scales of the ? ament deeply ^-parted ; seeds orbiculai-, nearly 

 wingless. — This miniature tree is found on the summits of Mt. Clinton, Mt. Frank- 

 lin, &c., of the White Mts. It is scarcely more than a foot in height, often but a 

 few inches, the branches few and straggling, the lvs. \ to f diam., smooth both 

 sides pale and distinctly reticulate beneath, and on petioles 1 to 2" long. (B. Littel- 

 iana Tuekerman.) 



3. AL'NUS, Tourn. Alder. (The ancient Latin name from Celtic 

 al, near, Ian, the river bant.) J Aments cylindric, drooping, tlie 

 bracts witb 5 bractioles beneath. ; calyx 4-parted ; stamens 4, anthers 

 2-celled. ? Aments ovoid, bracts cuneate, truncate, fleshy, 2-flowered ; 

 calyx of 4 scales adnate below to the bracts, all persistent and woody 

 in fruit ; fruit compressed, wingless or wiiiged. Shrubs arising from 

 large and strong roots. Buds pedunculate. Lvs. plicate in vernation, 

 S Aments panicled. (Fig. 111.) 



§ Emit ivingless, Nos. 1, 2. §§ Ti-uit iroadly winged. (Alxastee, Spach.) No. 3. 



1 A. incana Willd. Speckled Alder. Black Alder. Los. submembranous, 

 oblong, acutisb, obtuse at base or cordate, margin Bomewhat lobed, sharply ser- 

 rate, glawous-pubescent beneath; veins hirsute, their axils naked; stip. oblong- 



