1 68 UNIVERSITY OF COLORADO STUDIES 



species of Carex and one of Eleocharis; (3) Shrub zone, a Salix-Betula 

 formation ; (4) Forest zone, the principal formation of the area, consist- 

 ing of a dense dry forest of Pinus murrayana and Pinus fiexilis and a 

 moist forest of Picea engehnanni. Engelmann spruce forest is the 

 characteristic formation of the sub-alpine region. 



The growing season is short, extending from May 15 to October 1. 

 The seasonal limits are as follows: Spring, May 15 to July 1; summer, 

 July 1 to August 15; autumn, August 15 to October 1. The spring 

 aspect is characterized by the blooming of plants in the drier parts of 

 the forest zone and by the complete absence of fresh vegetation in the 

 sedge zone. The summer is marked off by the blooming of water lilies 

 and the appearance of a rich herbaceous flora in all the zones. In the 

 autumn a few late-blooming species appear, chiefly of the gentian family. 



The flora of Redrock Lake consists of 140 species, in 100 genera and 

 41 families. The following families are well represented: Gramineae, 

 8 species; Cyperaceae, 6 species; Salicaceae, 5 species; Ranunculaceae, 

 8 species; Saxifragaceae, 6 species; Rosaceae, 8 species; Papilionaceae, 

 7 species; Gentianaceae, 10 species; Scrophulariaceae, 12 species; 

 Compositae, 15 species. The extension of the altitudinal distribution 

 of 15 species is noted. A table giving the geographical range of the 

 families, genera and species shows the wider relations of the Redrock 

 Lake flora. 



Future papers by the writers will discuss the ecology of about 25 lakes 

 occurring at various altitudes in the Rocky Mountain region. These 

 lakes are of various geologic types and are in different ecological stages. 

 Comparisons of these lakes with one another and with those studied 

 by other botanists will be made. 



