PLEUROPOQON GK AMINES 755 



POA 



simple racemes. Spikelets 5-20-flowered, all perfect or the up- 

 per staminate. Two lower glumes empty, unequal, thin-mem- 

 branous, 1-nerved, or the second imperfectly 3-nerved : flowering 

 glumes longer, membranous, 7-nerved, the middle nerve excur- 

 rent as a short point or awn. Palets nearly equalling the glumes, 

 2-keeled, the keels winged or appendaged. Stamens 3. Styles 

 short, with plumose stigmas. Grain free, enclosed in the glume 

 and palet. 



P. Californicnm Benth. Vasey Grasses Pac. Slope, ii, 68. Stems 

 erect, or somewhat decumbent at base, rather weak, 2-4 feet high : sheaths 

 smooth, equalling or exceeding the internodes, the lower ones short and 

 membranous: ligules 2-3 lines long: leaves flat or folded, 3-21 inches long, 

 1-3 lines wide, obtuse, smooth, or barely rough above: panicle a simple 

 lecund raceme, 6-12 inches long : spikelets linear-oblong, 10-20-flowered, 

 about 1 line long: empty glumes oblong, obliquely obtuse, smooth, 1-nerved 

 below, the first 1-1 ^ lines long, the second 1 line longer: flowering glumes 

 ranee-oblong, erose or dentate at the membranous obtuse apex, scabrous, 

 strongly 7-nerved, 3-4 lines long : awn arising below the apex, 1-5 lines 

 long : palets oblong, obtuse, nearly equalling the glumes. In low meadow 

 sands, southern Oregon to California. 



P. refractum Benth. Vasey 1. c. 69. Tufted from a strong creeping 

 lootstock: stems rather weak, 2-4 feet high, erect, smooth, simple: sheaths 

 nearly smooth, equalling or slightly exceeding the long internodes : ligules 

 1-2 lines long, truncate : leaves flat or folded, scabrous above, 2-10 inches 

 long, 2-4 lines wide : panicle a simple secund raceme of 6-10 spikekts 

 pendent on recurved pedicels, 6-12 linee long: spikelets linear-oblong, 

 8-12-flowered, about 1 inch long : empty glumes lance-oblong, obtuse or 

 emarginate, often denticulate, thin, smooth, 1-nerved, 2-3 lines long, the 

 second slightly longer: flowering glumes lance-oblong, erose or dentate at 

 the truncate membranous summit, nearly smooth, prominently 7-9- nerved, 

 33^-4 lines long : awn arising at the apex, 2-4 lines long : palet linear, 

 emarginate, shorter than the glumes. Along mountain streams, Oregon 

 and Washington. 



45 POA L. Sp. 67. 



Annual or perennial grasses with flat or convolute leaves and 

 numerous spikelets in open or contracted panicles. Spikelets 

 2-6-flowered, compressed, the rachella usually glabrous. Flowers 

 all perfect or rarely dioecious or polygamous. Glumes membran- 

 ous, keeled, the two lower empty, 1-3-nerved: the flowering 

 glumes longer than the empty ones, generally with a tuft of cob- 

 webby hairs at base, 5-nerved, the marginal nerves usually pu- 

 bescent. Palets a little shorter than the glumes, 2-nerved or 

 2-keeled. Stamens 3. Styles short, distinct, with plumose stig- 

 mas. Grain free, or sometimes adherent to the palet. 



2 MELICOIDES Glumes obtuse or barely acute, the empty 

 ones 1-5-nerved, the flowering ones without cobwebby hairs at 

 base, not prominently keeled. 



P. argentea Howell Vasey Bull. Torr. Bot. Club, xv, 11. Stems 

 slender, loosely tufted, 6-8 inches high, erect or somewhat decumbent at 

 base : sheaths loose and membranous, longer than the internodes : ligules 

 acute, l%-2 lines long : leaves of the sterile shoots numerous, curved, 



