11 



This is, next to the Festucea', the largest tribe in the 

 order, numbering seven hundred species arranged in 

 forty-six genera. The species are distributed through- 

 out all the temperate and colder regions of the world 

 and many occur within the Tropics. The genus A<irostis, 

 from which the tribe derives its name and from which 

 comes the word u agrostologist,"has about one hundred 

 species, found in all parts of the world, especially in 

 the north temperate zone. Some of our most important 

 meadow grasses — notably Berd's-grass and Timothy — 

 belong to this tribe. 



Aristida Linn.* Epirampes Presl.* 



Stipa Linu." Polypogon Desf. 



Oryzopsis Michx. Limnodia L. I!. Dewey.* 



Milium Linn." (Thurberia Benth. I 



Muhlenbergia Schreb. ' Antagrostis Griseb. 



Bracliyelytrnm Beauv.* Cinna Linn." 



Lvcnnis Kunih. Agrostis Linn.* 



Pereilenia Preal. Gastridium Beauv. 



Heleocbloa Host.* Calamagrostis Roth.* 



Phlenin Linn. Aininophila Host.* 



Alopeeurus Linn." Calamovilfa Seribn.* 



Coleantbus Seid. Apera Adans. 



PhippBia B. Br.* Lagnrus Linn. 

 Sporobolus R. Br.* 



Tribe IX. — Aiene<r. 



Spikelets two- to several-flowered; outer empty glumes usually 

 longer than the first floral glume; one or more of the floral 

 glumes awned on the back or from between the teeth of the bifid 

 apex; awn usually twisted or geniculate; the callus, and usually 

 the joints of the rachilla, hairy. 



A tribe comprising twenty-three genera and over 

 three hundred species widely distributed in the tem- 

 perate regions of both the Old and the New World, 

 particularly abundant in South Africa and Australia, 

 a tew extending beyond the arctic circle. 



