AGROSTIDEJS. 337 



There are about 120 species widely spread over the warmer and 

 temperate regions of both the Eastern and the Western Uemi- 

 spheres, being particularly numerous in the Andes of South America. 

 Bentham says: "They are frequently regarded as forming a" 

 section of Agrosfis, from which they differ cliiefly in the more 

 developed palea and the usual presence of the bristle continuing 

 the rachis of the spikelet, whilst others again refer Deyenxia to 

 the supposed distinct tribe Arnndinecv, on account of tlie hairs 

 surrounding the flowering glume. But these hairs are present in 

 almost all species of Agrostis." 



The northern species differ from Agrostis in the prolongation 

 of the rachilla into a bristle or stipes, usually, but not always, 

 hairy, in the larger spikelets, with the palea nearly as long as the 

 glume, and the usuallv hairv rachilla. 



Bentham still retains tlie genus Calamagrostis Adans. for 

 some 5 species, none of whicli are found in Xorth America. 

 Hackel places Degeuxia as a section of Calamagrostis. 



A. Leaf-blades involute, setaceous or rigid (a) 



a. Panicle thin, 4-7 cm. long, purple, spikelets 3.5 mm. 



long 1 



a. Panicle thin, 6-l'2 cm. long, whitish, spikelets 6-T mm. 



long '2 



a. Panicle thin. 10-15 cm. long, spikelets 4 mm. long. . 3 

 a. Panicle thin, 10-14 cm. long, spikelets 5.5 mm. long. 4 

 a. Panicle rather close. 8-10 cm. long, fine pubescence at 

 the base of the blade, light green, spikelets 3-4 mm. 



long 5 



a. Panicle dense, 7-10 cm. loug, fine wool at the base of 

 the blades; spikelets 4 mm. long 6 



a. Panicle dense, blades scabrous, 5-8 cm. long; spike- 



lets 4-4.7 mm. long 7 



B. Leaf-blades fiat or sometimes involute (b) 



b. Base of the blades softly woolly; panicle open, thin, 

 whitish 8 



b. No soft wool at the base of the blade; a ring of short 



hairs iu 11 ^ (c) 



