BETULACE^. 



325 



cone. Seeds without albumen. — Trees or shrubs, with alter- 

 nate simple leaves and deciduous stipules. 



1. BETULA. Tourn.— Birch. 

 (Said to be derived from Betu, the Celtic name for the birch.) 



Sterile Fl. Ament imbricate, cylindric ; scales ternate, the 

 middle one bearing the stamens. Fertile Fl. Ament ovoid- 

 oblong ; scales trifid, 3-flowered. Nuts compressed, winged on 

 each side. 



1. B. populifolia Ait.: leaves deltoid, long-acuminate, unequally serrate, 

 very smooth ; petioles smooth ; fertile aments cylindric, pendulous ; scales 

 with roundish lateral lobes. 



Rocky woods. Can. Mass. N. Y. W. to Ark. May.— A tree from 20—30 

 feet high, with white bark, not easily separable into layers. Leaves tapering 

 to a long point. Aments pedunculate. While Birch. 



2. B.exceha Ait,: \ea.\es ovate, acute, serrate, smooth on both sides; 

 petioles pubescent, shorter than the peduncles ; fertile aments ovate, erect ; 

 scales with rounded lateral lobes. B. luieo. Mich.f. 



Low grounds. N. Eng. and N. Y. May, June. — A tree from 40 — 60 feet 

 high, with a yellowish bark which is slightly fragrant. Fertile aments about an 

 inch long. Used for fuel and for cabinet work. The bark is valuable for tan- 

 ning. Yellow Birch. 



3. B. nigra Linn. : leaves rhombic-ovate, doubly serrate, acute, pubes- 

 cent beneath, entire at base ; fertile aments ovate ; scales villous, with the 

 segments linear and equal. B. mhra Mich. f. 



Banks of streams. N. Y. to Car. April, May.— A tree 40—60 feet high, with 

 a smooth bark. Leaves on short petioles. Fertile aments three-fourths of an 

 inch long. The wood is of little consequence. Red Birch. 



4. B. papyracea Ait. : leaves ovate, acuminate, doubly serrate, hairy on 

 the veins beneath ; petioles smooth ; fertile aments pedunculate, nodding ; 

 scales with short and rounded lateral lobes. B. papyrifera Mich. 



Can. N. Eng. N. Y. N. to Hudson's Bay. May, June.— A tree 40—70 

 feet high ; the bark white externally, easily separable into thin layers which 

 have a reddish color. Fertile aments about an inch long. The bark is used by 

 the hidians for constructing their canoes ; and the wood is sometimes employed 

 for cabinet work. Canoe Birch. 



5. B. knta Linn. : leaves cordate-ovate, sharply serrate, acuminate ; 

 nerves beneath and petioles hairy ; fertile aments elliptic-ovoid, erect ; scales 

 roughish-pubescent ; lobes nearly equal, obtuse, with elevated veins. B. 

 carpinifolia Mich. 



Woods. Can. to Geor. April, May. — A tree 30 — 60 feet high, with nume- 

 rous slender branches which are spotted with white. Leaves cordate and some- 

 what unequal at base, long-acuminate. The wood has a close grain and is 

 susceptible of a fine polish. The bark and young twigs are fragrant and aro- 

 matic. Sweet Birch. Cherry Birch. 



6. B. jnimila Linn. : young branches pubescent or smoothish ; leaves 

 roundish-obovate, serrate, smooth, subsessile; petioles densely pubescent 

 beneath; fertile aments oblong. B . glandidosa Mich. 



