GRASSES OF IOWA. 



183 



Fig. 129. Flower of Arrhenatherum avenaceum. (Charlotte M. King.) 

 TRIBE IX.— AVENEAE. 



Spikelets 2 to several-flowered ; outer, empty glumes usually longer 

 than the first floral glume; one or more of the flowering 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 23 genera and over 300 species, widely distrib- 

 uted in the temperate regions of both the Old and the New r World, 

 particularly abundant in South Africa and Australia, a few extending 

 beyond the Arctic Circle. 



Several of the species are of economic value as forage plants. Tall 

 meadow oat grass {Arrhenatherum avenaceum) and velvet grass or 

 mesquite, as it is known in Oregon and Washington, both introduced 

 from Europe, are grasses of much agricultural value, especially the first 

 named. Tufted hair grass (Deschampsia caespitosa) , a common grass in 

 the Rocky Mountains of the west and northwest, is of some local value 

 as a forage plant, especially for low, wet soils. Cultivated oats {Avena 

 sativa), used largely in the south and on the Pacific coast for pasturage 

 and hay, and generally cultivated as a cereal, is the best known example 

 of this tribe. 



