MONOECIA, POLYANDRIA., 175 

flowered. Calix consisting of scales. Co- 
‘rollanone. Stamina 10 to 12. Fem. Ca- 
lix scales 2-flowered. Corolla none. Seed 
4, alated.— Nutt. 
a” 
1. B. leaves deltoid, long, acuminated, unequally populifolia. 
serrated, very glabrous; lateral scale lobes of 
the strobiles subrotund; petioles smooth.— 
Willd. 
B. acuminata, Ehrh. 
B. lenta, Du Roi. harbk. and Wangh. Amer. 
fcon. Mich. Arbr. forest. 2. p. 139. t. 2. 
White Birch. Old-field Birch. 
A middling sized tree. In woods on the Chester-road. h- 
June. 
2. B. leaves ovate, acuminate, doubly serrated ; papyritera. 
veins hirsute beneath ; petiole smooth ; feminine 
aments pedunculated, nutant ; lateral scale lobes 
short, suborbiculate.— Willd. and Pursh. 
B. papyracea, Willd. and Pursh. 
Icon. Mich. f. Arbr. forest. 2. p. 133. t. 1. 
Paper Birch. Canoe Birch. 
. A large tree. On the banks of the Schuylkill near the falls; 
on Timber-creek, and elsewhere in Jersey. h. May. 
5. B. leaves cordate-ovate, narrowly serrated, lenta. 
acuminate ; nerves and petioles hairy beneath ; 
scales of the strobiles smooth: lobes obtuse, 
equal, with raised veins.—/Villd. and Pursh. 
- B. carpinifolia, Ehrh. 
B. nigra, Du Roi. harbk. and Wangh. Amer. 
Icon. Mich. Arbr. 2. p. 145. t. 4. 
Mountain Mahogany. Black Birch. Cherry Birch. 
Sweet Birch. 
A large and elegant tree. Its branches have a fine sweet 


