34 POACEAE. 



3. A. diegoensis Vasey. Perennial from slender stoloniferous 

 rootstocks; culms erect, 4-8 dm. high; sheaths minutely scabrid; 

 blades 6-15 cm. long, 2 mm. wide, scabrid; panicle lax, narrow, 

 6-14 cm. long, its branches erect; spikelets 3-4 mm. long; empty 

 glumes nearly equal, scabrid; callus hairy at the base of each margin 

 of the flowering glume; flowering glume 2.5-3 mm. long, scabrid 

 especially on the margins, 4-toothed; palea obsolete. 



Not known within our limits, but occasional in San Diego County 

 and extending north to Washington. 



18. GASTRIDIUM Beauv. Nit-grass. 



Cspspitose annuals with flat leaves and shining spike- 

 like panicles. Spikelets 1-flowered, hermaphrodite; ra- 

 chilla prolonged behind the palea. Empty glumes 2, 

 equal, enlarged or saccate at the base, keeled above; 

 flowering glume much shorter than the empty ones, 

 hyaline, truncate or obtusely 2-lobed, awnless or bearing 

 a slender awn just below the apex. Palea narrow, about 

 the length of the glume. Stamens 3. Styles short, dis- 

 tinct; stigmas plumose. Grain subglobose, free, in- 

 cluded within the ventricose base of the glume. 



1. G. lendigerum (L.) Gaud. Culms more or less tufted, erect, 

 15-60 cm. high; sheaths shorter than the internodes, smooth; leaves, 

 3-10 cm. long, 2-4 mm. wide, acuminate, scabrous; panicle spike- 

 like, 5-10 cm. long, 1 cm. wide, pale green and shining; spikelets 

 lanceolate, 5-6 mm. long; empty glumes scabrous above; flowering 

 glume hairy, bearing a slender awn below the middle. 



Common on dry ground in the chaparral belt throughout our 

 range. Native of southern Europe. 



Tribe 5. AVENEAE. Oat Tribe. 



Spikelets 2-several-flowered ; outer empty glumes 

 usually longer than the first flowering glume; 1 or more 

 of the flowering glumes awned on the back or from be- 

 tween the teeth of the bifid apex; awn usually twisted 

 or geniculate. 



Spikelets articulated with the pedicels below the 



empty glumes. 19. Notholcus. 



Spikelets not articulate below the empty glumes. 

 Awns dorsal. 



Spikelets small, less than 1 cm. long. 20. Deschampsia. 



Spikelets 1 cm. long or more. 21, Avena. 



Awns terminal, rising from between the lobes 



or teeth. 22. Danthonia. 



