44 



SALICACEAE (WILLOW FAMILY) 



ers arise from a cup-shaped disk. The stamens are 8-30 or 

 more. 



P. tremuloides, Trembling Aspen. A tree 6-20 m. high, with 

 smooth greenish-white baric. Leaves roundish-heart-shaped, with a 

 short sharp point and stnall somewhat regular teeth. Petioles long 

 and slender and laterally flattened. Scales cut into 3-4 deep linear 

 divisions, fringed with long hairs. Bud scales glabrous, or merely 

 ciliate. Common in thickets and clearings. 



P. grandidentata, Large-toothed Aspen. Tree often 20 m. high 

 with smoothish gray bark. Leaves roundish-ovate, with large and ir- 



a-c, Populvs delloides, Cottonwood; a, winter bud; 6, fruit; c, leaf, d-g, P. 

 balsamifera. Balsam poplar; d, winter bud; e, staminate flower; /, pistillate 

 flower; g, leaf. 



regular sinuate teeth, densely covered when young with white silky 

 ■wool, smooth on both sides when mature. Petioles laterally flattened. 

 Scales cut into 5-^ unequal small divisions, slightly fringed. Bud- 

 scales toraentose. 

 P. balsamifera, Balsam Poplar. Tree 6-30 m. high, the buds large 



