62 



Fig. 40. Stipa spartea Trin. PORCUPINE-GRASS.— a, A single spikelet; b,& 

 floret more highly magnified, showing the sharp-pointed, bearded callus at the 

 base. Figs. 90 and 91, in Bui. 7, and 423 to 440, in Bui. 17, illustrate other species 

 of the genus Stqxx. 



40. STIPA Linn. Sp. PI. 78. 1753. Spikelets 1-flowered; rachilla articulated 

 above the empty glumes and produced below the flowering glume into a strong, 

 bearded, obconical, and sharp-pointed callus. Glumes 3, the first two empty, 

 thin, membranaceous, subequal, acute or bristle-pointed, the 3d or floral glume 

 narrow, subcoriaceous, closely rolled around the flower and usually shorter 

 palea, terminating in a twisted and geniculate, simple awn which is articulated 

 with its apex. Grain terete and closely enveloped by the hardened fruiting 

 glume. Tufted perennial grasses with very narrow or involute leaves and 

 usually open panicles. 



Species about 100, widely distributed throughout the tropical and temperate 

 regions of the world. About 30 species are recorded as occurring within the 

 United States, chiefly Southwestern. 



