22 Flora of the Palouse Region 



glumes unequal, acute, persistent: flowering glumes 2-4, usually 

 shorter than the empty ones, deciduous, 2 -toothed, bearing a 

 dorsal awn below the apex or the lower one sometimes awnless: 

 palet narrow, hyaline, 2-toothed: grain free, enclosed in the flow- 

 ering glume. 



Leaf blades and sheaths smooth. T.. cernuum. 



Leaf blades and sheaths hairy. T. caxescexs. 



T. cemuum Trin. Culms .6-1 m. tall, erect, the nodes pale: leaf blades 

 flat, merely scabrous, 15-20 cm. long, 6-10 mm. wide: panicle 10-15 cm. long, 

 loose, nodding; branchesin distant whorls, capillary, cernuous, flower bearing 

 above the middle: spikelets 2-4 flowered, 6-7 mm. long without the awn: 

 flowering glume 2-3 mm. long bearing an awn about twice its length. Moist 

 woods and copses. 



T. eanescens Buckley. Much like the preceding, the leaf blades and 

 sheaths pubescent: nodes usually dark: panicle erect, 7-16 cm. long. In 

 coniferous woods. 



36. AVEXA. 



Inflorescence a panicle: spikelets 2-many-flowered or rarely 

 1 -flowered; lower flowers perfect, the upper often staminate: 

 empty glumes somewhat unequal, membranous, persis- 

 tent: flowering glumes 2-many, rarely one, deciduous, rounded 

 on the back, acute, generally bearing a dorsal awn; apex often 

 2-toothed; palet narrow, 2-toothed: grain oblong, deeply fur- 

 rowed, enclosed in the flowering glume and palet, free or some- 

 times adherent to the latter. 



A. fatua var. glabrescens Coss. Culms stout, pale, smooth, .5-1 m. tall, 

 erect: leaf blades broad and fiat, the sheaths about equalling the internodes: 

 panicle loose, 15-20 cm. long, spikelets, including awns, 3.5-4 cm. long, 

 erect or drooping, on slender branches: flowering glume smooth, except the 

 scabrous apex and the ring of stiff white hairs at the base, bearing on the 

 back a geniculate, stout, twisted awn below the 2-cleft apex. A troublesome 

 weed in cultivated land. 



37. ARRHENATHERUM. 



Inflorescence a contracted or open panicle: spikelets 2-flowered, 

 lower flower staminate, upper perfect; rachilla extending beyond 

 the flowers: empty glumes thin-membranous, keeled, very acute 

 or awn-pointed, unequal, persistent: flowering glumes 2, rigid, 

 5-7-nerved, deciduous, the first bearing a long bent and twisted 

 dorsal awn inserted below the middle, the second unawned; palet 

 hyaline, 2-keeled: grain ovoid, free. 



A. avenaceum Beauv. Glabrous perennial, 1-1.5 m. high: culm leaves 

 3, the blades flat, minutely scabrous, the sheaths shorter than the inter- 

 nodes: panicle shining, 15-25 cm. long, rather narrow, the branches sub- 



