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UNIVERSITY OF COLORADO STUDIES 



are found in this area. It grows as a rule in rather moist situations, 

 either in the gulches or on mesa slopes and top. 



Kinnikinik. Arctostaphylos uva-ursi (L.) Spreng. — This plant 



Fig. 8. — Cottonwoods and Willows. Populus angustifolia James; Salix amygda- 

 loides Anders.; S. exigua Nutt. — In the map the willows are represented by solid black 

 dots, the cottonwoods by inclosed areas. The cottonwoods and willows are distinctly 

 stream and gulch plants. The narrowleaf cottonwood occurs in Pole Canyon but is not 

 found in Cemetery Gulch. There are also fewer willows in Cemetery Gulch. These 

 differences are accounted for by the fact that the latter gulch is not as old and deep as 

 Pole Canyon and hence does not receive as great an amount of water. The same reason 

 will account for the fact that there are more willows in Pole Canyon than in Cemetery 

 Gulch. The common western cottonwood, Populus sargentii Dode, is not found in either 

 gulch. Its distribution in the mountains is more commonly in the deeper canyons whose 

 streams flow out into the plains and connect with larger eastward-flowing streams. Such 

 a distribution indicates that the western cottonwood is more distinctly a plains form 

 than the narrowleaf cottonwood and that it spread to the mountains up the larger water 

 courses which stretched out to the plains. 



