TREES AND SHRUBS 45 



SALICACEAE. Willow Family 



Trees and shrubs with simple, alternate, deciduous leaves; 

 flowers dioecious, in catkins; bracts of the ament scale-like; perianth 

 none; stamens 1 to several, ovary 1-celled; stigmas 2; fruit a small 

 capsule; seeds very numerous, small comose. 



Bracts incised; disk cup-shaped; stamens nu- 

 merous; stigmas much expanded; winter 

 buds with several scales. 1. Populus. 



Bracts entire; disk represented by one or two 

 small glands; stamens few, generally less 

 than 5; stigmas much expanded; winter 

 buds with a single scale. 2. Salix. 



I. POPULUS L. Cottonwood, Aspen 



Trees with rough, light-colored bark and scaly, resinous buds; 

 leaves usually long petioled, ours somewhat coriaceous, with promi- 

 nent veins; flowers in pendulous aments, appearing before the leaves; 

 seeds with a conspicuous white coma (the "cotton"). 



P«tloles flattened laterally; leaves broad, del- 

 told to rotund. 



Leaves broadly ovate to rotund, abruptly 

 short acuminate, 1 to 2 inches long and 

 broad, paler beneath; trees of the high 

 mountains. 



Leaves broadly deltoid, acuminate, 2 to 3 

 inches long and 2% to 4 inches broad, 

 of the sa.me color on both surfaces; trees 

 of the lower valleys. 



Petioles terete or channeled on the upper sur- 

 face; leaves narrower, ovate to narrowly 

 lanceolate. 

 Leaves ovate to ovate lanceolate, 2% to 4 

 Inches long, 1 to 2 inches broad, rather 

 coarsely crenate, both surfaces of the 

 same color. 

 Leaves broadly to narrowly lanceolate, 3 to 6 

 inches long and 1% inches wide or less, 

 finely serrate with blunt teeth, much 

 paler beneath. 



P. tremuloidea. 



P. wislizenl. 



P. acuminata. 



4. P. angustifolia. 



