38 WILD FLOWERS AND TREES OF COLORADO 



the name of the botanist who has described the plant is affixed to the 

 scientific name. This is done in order that anyone wishing to examine 

 the original description of the plant may more easily find it. 



Forest formations. — It is a simple matter to classify the forests of 

 Colorado. They fall into two groups, those of the plains region and 

 those of the mountain districts. The former are of slight economic 

 importance at the present time but their existence suggests the possi- 

 bility of tree-planting which may in time become highly profitable. 

 River-bottom forests and pine-ridge forests occur in the plains region 

 to the east of the continental divide, while in the western part of the 

 state there are large areas with a growth of quaking aspen and of pinyon 

 pine which it is difficult to classify. They might be termed either pine- 

 ridge or foothill forests. In the mountain districts there are no trees 

 of importance except the "evergreens." 



Forest formations of mountain districts. — These are composed of 

 coniferous trees, the various species of pine, spruce and fir and the single 

 species of Douglas spruce. Generally the foothills support an open 

 formation of rock pine 1 while in the moister canyons there are Douglas 

 spruces. 2 In southern Colorado the pinyon pine 3 forms a conspicuous 

 part of the foothill forest and in places in the southern and western parts 

 of the state there are some oaks of consequence. In the montane 

 region a closer forest exists, composed largely of lodgepole pine, 4 with 

 some Colorado blue spruces 5 along the streams. The best timber, how- 

 ever, is in the sub-alpine spruce forests. These consist essentially of 

 Engelmann spruce 6 with some admixture of limber pine, 7 sub-alpine 

 and white fir 8 and, in places, bristle-cone pine. 9 



Forest formations of the plains region. — The river-bottom and 

 pine-ridge forests occupy essentially different habitats. Along the 

 water courses there is found a good growth of cottonwoods and willows 

 with occasional box-elders, hackberries, mountain maples and alders. 

 Where the stream has not cut a deep bed, and the ground slopes gently 



1 Pinus scopulorum. 6 Picea engelmanni. 



■ Pseudotstiga mucronala. i Pinus flexilis. 



3 Pinus edulis. 8 Abies lasiocarpa and Abies concolor. 



* Pinus murrayana. » Pinus aristata. 



» Picea parrayana. 



