Trees of the Nouthkrn I United ^States 113 



especially on the banks and flood plains of creeks and rivers. 

 Quebec to Man., south to Fla., Kan., and N. Mex. 



5. Populus nigra L. Black Poplar. A large tree with 

 terete twigs. Mature leaves firm. ])roadly deltoid, abruptly 

 acuminate at the apex, broadly cuneate or obtuse at the base, 

 crenate, 2-4 in. long. Naturalized from Europe. N. Y. and 

 southward along the Delaware R. 



(j. Populus itdlica Moench. Lombardy Poplar. A 

 spire-like tree of rapid growth. C»ommonly planted for orna- 

 ment. 



7. Populus grandidentata Mx. Largetooth Aspen. A 

 tree with smooth, greenish-gray bark. Leaves tomentose when 

 young, glabrous when mature, short-acuminate, obtuse or 

 truncate at the base, "l-i in. long. Wood soft and white ; used 

 for paper pulp. In rich moist soil. N. S. to Ont. and Minn., 

 south to N. J. and Ohio, and in the Alleghanies to Tenn. 



8. Populus tremuloides Mx. American Aspen. A 

 slender tree with light green, smooth bark. Leaves usually 

 short-acuminate at the apex, iifiely crenulate, truncate, rounded 

 or subcordate at the base, 1-3 in. broad. Petioles very slender, 

 causing the leaves to quiver and rustle in the slightest breeze. 

 Wood white and soft ; used for making coarse paper. In 

 moist or dry soil. Newf. to Alaska, south to N. J., Ohiio, Ky., 

 and Neb. ; in the Rocky Mts. to Mexico and to Lower Cal. 



(in. Salix (Tourn.) L. Will.nv. 



Shru.bs or trees with alternate simple serrate i)innately 

 veined leaves and axillary huds with a single outer scale. 



Diecious ; flowers in aments ; fruit a capsule, the seeds 

 with long cottony hairs ; leaves sometimes with glands on 

 the petiole or at the base of tlie blade and with gland-tipped 

 teeth. Twigs self-pruned l\v means of basal brittle zones. 

 The charcoal from the larger si)ecics used for making gun- 

 powder. 



1. Twigs decidedly pendulous or "weeping", green or yel- 

 lowish-green ; leaves linear-lanceolate, acuminate, ser- 

 rulate, smooth, rather pale beneath, petioles glandular 

 above; capsule glabrous, pedicel very short, stigma 

 sessile, S, bahylonica. 



