272 THE STUDY OF PLANT COMMUNITIES * Chapter X 



stantly present in small numbers, it is only a minor constituent. 

 Lodgepole pine (Finns contorta) is often present, especially in wet 

 meadows, but its role is primarily successional. Mountain hemlock 

 (Tsnga mertensiana) and white fir (Abies concolor) occur in an 

 extremely irregular fashion. Of the shrubs, which are few, Kibes 

 viscosissimum and Symphoricarpos rotimdifolins are the most 



FlG. 141. Virgin forest in the Sierran montane zone of California, in this 

 instance made up of sugar pine (Pinus lambertiana), ponderosa pine (P. pon- 

 der -osa), and white fir (Abies concolor).— U. S. Forest Service. 



abundant and most constantly represented. The herb flora is also 

 sparse. Constant species are Chrysopsis breweri, Fedicnlaris semi- 

 bar bata, Gayophytnm ramosissimum, Firola picta and Monardella 

 odoratissima. The yellow-green lichen (Evernia vidpina) is con- 

 spicuously present on the trees throughout the zone. 



Although the altitudes in the Sierra are often greater than those 

 of the Rockies, conditions are severe and timber line is lower, 

 varying from about 7,000 feet in the north to some 10,000 feet in 

 southern California. The characteristic trees are Finns albicaidis, 



