53 



shorter, thin, and hyaline, finely pointed or shortly bifid, with a fine 

 dorsal awn below the middle, which is twisted at the base ; palet 

 two-nerved ; style short. 



1. A. earyophylla, Linn. Introduced and naturalized. 



2. A. prseoox, Linn. Introduced and naturalized. 



Desohampsia, Beauv. (Aira of authors.) 



Spikelets two-flowered, mostly in a loose panicle with slender 

 branches, rhachis hairy and produced into a hairy bristle, which 

 rarely bears an empty glume ; outer glumes acute, keeled, with sca- 

 rious margins ; flowering glumes obtuse, more or less toothed, with 

 a fine dorsal awn below the middle. Palet prominently two-nerved, 

 often two-toothed. Spikelets larger than in Aira. 



1. D. atropurpurea, Wahl.% White Mountains. 



2. D. csespitosa, Beauv. North and West. Bunch grass. 



D. csespitosa, var. Bottnica. (Aira Bottnica, Walk.) California 

 and Oregon. 



D. csespitosa, var. arctica. Rocky Mountains. 



D. csespitosa, var. longiflora, Trin. California. 



This is an exceedingly variable species, having a very wide dis- 

 tribution in this and other countries. It is rare east of the Missis- 

 sippi, but on the elevated plains and in the Rocky Mountains, also 

 in California and Oregon, it is one of the common bunch grasses 

 which afford pasturage to cattle and horses. In the East it is found 

 in the hilly regions of New England and the Alleghanies. 



3. D. calycina, Presl. (D. danthonioides, Munro.) California to 



Alaska. 



4. D. elongata, Munro. (Aira elongata, Hook.) California to Brit- 



ish America. 



5. D. flexuosa. (Aira flexuosa, Trin.) New England, South, and 



West. 



6. D. gracilis, Vasey. Southern California. 



7. D. holciformis, Presl California. 



8. D. latifolia. (Aira latifolia, Hook.) California to Alaska. 



Coeynephobus, Beauv. 



Spikelets two-flowered, with the rhachilla produced into a short 

 hairy bristle; glumes much as in Deschampsia, but distinguished by 

 the peculiar articulate club-shaped awn of the flowering glumes. 



