38 RAMALEY: XEROPHYTIC GRASSLANDS AT 
ress of the work a large collection has been accumulated which is 
kept as a special ‘dry grassland herbarium.’”’ Air temperature 
records have been kept for the growing season at Tolland (8,889 
ft.) and these have been compared with reports from the govern- 
ment stations at Boulder (5,340 ft.) and at Corona (11,660 ft.). 
Soil temperatures have been carefully studied at Boulder and at 
Tolland, while occasional records have been made in the higher 
altitudes. The present work does not in any sense cover the whole 







Pe ae ak 

‘ oan ae oe oe 

Fic. 1. sii of Colorado showing general oe features. The Conti- 
nental Divid zig-zag course north and so he foothills at the moun- 
tain front are indicated by the series of eat age Cae and Tolland are 
to the northwest of Denver. 


of Colorado (Fic. 1) but merely the area tributary to the Uni- 
versity at Boulder and the Mountain Laboratory at Tolland. 
Field work has been done chiefly in a rectangle about 40 miles 
east and west and 30 miles north and south with altitudes from 
5,000 to 14,000 feet above sea level (Fic. 2). 
In the following synopsis of xerophytic grasslands, descriptions 
are omitted because these are available in the writings of Shantz, 
Vestal, Pound and Clements (5), and the writer. Nichols’s (4) 
exposition of ecological concepts has been followed in choosing 
names for the different communities. The nomenclature of species 
is that of Rydberg (13). ; 
