14 



cylindrical, usually purplish, spiciform panicles, 1 to 5 cm. in length. Culms 

 slender, branching, and geniculate at the base, glabrous; nodes smooth; sheaths 

 loose, striate, glabrous, shorter than the internodes, margins smooth; ligule very 

 short, ciliate; leaf-blades 5 to 10 cm. long, 4 to 6 mm. wide, scabrous on both 

 sides and on the cartilaginous margins, sometimes nearly smooth beneath, not 

 narrowed at the cordate base, acute or acuminate. Panicles about 5 mm. in 

 diameter, somewhat exserted; rachis angular, pubescent; branches very short, 



1 or 2 flowered, approxi- 

 mate; setae 5 to 10, short, 

 unequal, involucrate, 3 to 8 

 mm. long, flexuous, green 

 or pm-plish, often barely 

 exceeding the spikelets, an- 

 trorsely scabrous. Spike- 

 lets ovate, acute, 2 mm. 

 long; first glume ovate, 

 acute, 3-nerved, one-third 

 as long as the spikelet; sec- 

 ond glume ovate, acute or 

 obtuse, about one-half as 

 long as the spikelet, 5- 

 nerved, mid-nen^e excur- 

 rent, the lateral ones anas- 

 tomosing or vanishing in 

 the hyaline margins ; third 

 glume equaling the flower- 

 ing glume, 5-nerved, sul- 

 cate, subtending a broadly 

 ovate, hyaline palea of its 

 own length; flowering 

 glume ovate, acute, trans- 

 verse 1 y midulate-striate 

 for its whole length, the 

 inclosed x^aleaequalingitin 

 length, striate, plane. 

 Texas to Mexico, West Indies, 

 Central and South America. 

 Specimens examined. — Texas: 

 San Diego, Smith 1897; 

 Bexar Co., 207 Jermy; Dal- 

 las, Eeverchon 1876. Cuba: 

 3472 Wright 1865. Mexico: 

 Chiapas, 3023a, 3336 Nel- 

 son 1895; City of Mexico, 

 7 Holway 1896; 3126 Holway 1898; Orizaba, 114, 247 Seaton 1891; 33 Nelson 

 1894; Plunia, 2482 Nelson 1895; Puebla, Nelson 1893; Chinantha, 350 Liebmann 

 1841, cited by Fournier^ under Setaria geniculata ; valley of Mexico, 231 Bour- 

 geau 1865-66; Colipa, 360 Liebmann 1841, cited by Fournier under Setaria 

 flava. 

 An extremely variable species, at once distinguished from the closely related C. gracilis 

 by its shorter, lanceolate or linear-lanceolate leaves and thicker, usually purplish 

 spikes. The form which Fournier referred to Setaria flava Kunth, differs from 



Fig. 4. — Chcetochloa gracilis: a, spikelet sbowing the setae and 

 second plume ; h, spikelet showiugtho first and third glumes ; 

 c, flowering glume, dorsal view. 



^ Hex. PI. Enuin. Gram. 45. 



