179] FLORA OF BOULDER, COLORADO 31 



hence the flowering season is short. In a period of about six 

 weeks, from the middle of July to the first of September, the 

 main part of the vegetation in these cool valleys is brought to 

 perfection. Species, which on the mesas had bloomed before 

 my arrival on the eighteenth of June, I found just in blossom 

 at Eldora on the mountainsides August thirty-first. 



I saw too little of the Montane Flora, since I spent only 

 six days in collections, where it occurs, to be able to separate 

 it definitely into plant-societies. But the chief types as I saw it 

 at Ward, Eldora, and Glacier lake, will be briefly described. 

 In the Montane Subzone there are, perhaps, six tolerably 

 distinct types of vegetation-association: a. The montane 

 forest (Sylvales). b. The montane bog (Paludosae). c. 

 The montane lake (Lacustres). d. The arid brush slope 

 (Arbustales). e. The montane meadow (Pratenses). f. 

 The montane stream (Amnicolae). 



a. Sylvales. The montane sylva consists of a close for- 

 est of lodgepole pine interspersed with some bull pine and 

 Rocky Mountain white pine, as well as with the various 

 spruces and firs. The spruces and firs occur principally in the 

 valleys, while on the barren ridges, the pines assume a scrub- 

 like form. On these ridges occur many peculiar species of 

 dwarf herbs golden rods, asters, fleabanes, cat's-feet, actin- 

 ellas, groundsels. A few of the more characteristic species of 

 the montane sylva are the following : 



Pinus scopulorum Pseudotsuga mucronata 



P. Murrayana Abies lasiocarpa 



Apinus flexilis Calamagrostis purpurascens 



Picea Engelmanni Trisetum subspicatum 



P. Parryana Avena striata 



