126 



POACEAE 



4. Aristida oligantha Michx. 

 Few-flowered x\ristida. Fig". 267. 



Aristida oligantha Michx. Fl. Bor. Am. 1: 41. 1803. 



Annual ; culms erect, branched at base and at all the 

 nodes, 30-60 cm. high, often woolly at the verj' base ; 

 blades 2 mm. wide or less, usually involute, as much 

 as 15 cm. long, sparingly pilose at base, the prophyllum 

 often conspicuous at base of branches ; panicles narrow, 

 loosely few-flowered, bearing a few scattered large 

 appressed short-pediceled spikelets ; glumes about 2.5 

 cm. long, slightly unequal, long-awned from a bifid 

 apex, the first strongly 7-nerved ; lemma a little shorter 

 than the glumes, the gradually narrowed neck scaber- 

 ulous, the callus rather minutely pubescent ; awns 

 about equal, widely spreading, 5-8 cm. long. 



Open ground, central Oregon to the interior valley of Cali- 

 fornia; common in the southeastern States. July-Sept. Type 

 locality: Illinois. 



5. Aristida adscensionis L. 

 Six-weeks Grass. Fig. 268. 



Aristida adscensionis L. Sp. PI. 82. 1753. 



Aristida bromoides H. B. K. Nov. Gen. & Sp. 1: 122. 1816. 



Annual ; culms much-branched at the base, 10-30 cm. 

 tall, erect or often spreading or prostrate; blades 2.5-5 

 cm. long, narrow, usually involute ; panicle narrow, 

 rather dense. 5-8 cm. long, the branches short, fascicled ; 

 glumes unequal, smooth except the keel of the first. 

 1-nerved. the first 5-6 mm. long, acutish. the second 

 7-8 mm. long, obtuse or slightly mucronate ; lemma 

 8-10 cm. long, smooth except upper portion of keel, the 

 callus with a dense tuft of short hairs, the apex scarcely 

 narrowed; awns equal, finally spreading, about 10 mm. 

 long, or the lateral sometimes shorter. 



Open ground, southern California (San Luis Obispo and 

 southward) to New Mexico and south to South America. Feb.- 

 Tune. Type locality: Island of Ascension. 



6. Aristida parishii Hitchc. 

 Parish's Aristida. Fig. 269. 



Aristida parishii Hitchc. in Tepson, Fl. Calif. 1: 101. 

 1912. 



Perennial ; culms tufted, 30-60 cm. tall. 

 smooth; sheaths smooth, ciliate at the throat; 

 blades ascending, firm, flat or more or less 

 involute, scabrous on the upper surface, 

 smooth below or scabrous toward the tip, 1-2 

 mm. wide, 15-30 cm. long; panicle narrow, 

 about 15 cm. long, the branches rather stout, 

 ascending or appressed, the lower 2-5 cm. long; 

 glumes somewhat unequal, short-awned, smooth 

 or scabrous on the keel, 1-nerved or the first 

 3-nerved, the second a little longer, 12 mm. 

 long; lemma a little shorter than the second 

 glume, very scabrous on the upper half, the 

 neck rather stout, not twisted, the awns ascend- 

 ing, the central about 2 cm. long, and the lateral 

 a little shorter. 



Dry ground, southern California. Apr.-July. Type 

 locality: Agua Caliente, Riverside County. 



