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JOHN ERNST WEAVER 



numerous at the tip than are those of Festuca. Poa roots branch 

 to the fourth order. Six plants were examined on the rim-rock 

 with an average root depth of 7.2 inches. Eight prairie spe- 

 cies of Poa growing on a southwest slope gave an average maxi- 

 mum depth of 9.7 inches. 



Fig. 11. Three imporant prairie grasses. Koeleria cristata (to the left), 

 Festuca ovina ingrata (center), and Poa sandbergii. All are relatively shallow 

 rooted. 



Koeleria cristata. {Fig. 11) 



This is a very common bunchgrass on the prairies of eastern 

 Washington, not infrequently occurring as abundantly as 6 

 clumps per square meter. However, the bunches are smaller 

 in diameter (0.5 to 2 inches, usually) than those of Festuca ovina 

 ingrata, and also of less height (1-2.5 feet) than Agropyron 

 spicatum. Koeleria flowers in late June or early July and like 

 Poa remains dormant until revived by the autumn rains. % 



