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UNIVERSITY OF COLORADO STUDIES 



here and there in both gulches, being best developed in shady, moist 

 places. They are also found in the lateral ravines on the north exposure. 

 Alder. Alnus tenuifolia Nutt. — The alders grow only in Pole 

 Canyon, being entirely absent from Cemetery Gulch. 



Fig. 6. — Box Elder and Mountain Maple. Acer negundo Torr., A. glabrum Torr. 

 — In the map box elder is represented by black dots. It is noticed that a greater number 

 of trees occur in Pole Canyon than in Cemetery Gulch. In the latter gulch the two trees 

 are quite young. In the map mountain maple is represented by inclosed areas. It is 

 here confined to Pole Canyon. It is most abundant on the south side of the stream on 

 the north slope. In the mesa region mountain maple grows near the bottom of the gulch. 

 At higher altitudes it is more frequently on steep hillsides. This difference is due to the 

 greater rainfall of the higher altitudes. There, the hillsides are moist enough for the 

 maple, while in the mesa region it must get into the gulches for sufficient water. 



Wax Flower. Edwinia americana (T. & G.) Heller. — This shrub 

 grows only near the head of Bluebell Canyon on the north exposure. It 



