Bouteloua triaena (Trin.) Scribn.

Bouteloua triaena (Trin.) Scribn. Proc. Acad. Phila 1891:307. 1891.
Triaena racemosa H.B.K. Nov. Gen. & Sp. 1: 179. 1816.
Eulriana Triaena Trin. Gram. Unifl. 239. 1824. (Based on Triaena racemosa H.B.K.) Alheropogon Triaena Spreng. Syst. 1; 293. 1825. (Based on Triaena racemosa H.B.K.) Dinebra cristata Presl, Rel. Haenk. 1: 293. 1830. (Type from Mexico, Haenke.) Triathera racemosa Desv. Opusc. 72. 1831. (Based on Triaena racemosa H.B.K.) Eulriana ? cristata Kunth. Enum. PI. 1: 281. 1833. (Based on Dinebra cristata Presl.) rnof/iecagraciiis Fourn. Mex. Pl.Gram. 2: 141. 1886. (Type from Cuernavaca, Mexico, Bcr/a«(ii(T 1016.)
Perennial; culms tufted, erect to widely spreading, 20-45 cm. tall, or in widely spreading plants as much as 80 cm. long; sheaths glabrous; ligule ciliate, 0.5-1 ram. long; blades flat, 5-20 cm. long, 1-3 mm. wide, glabrous or scabrous, the margins more or less papillose-ciliate near the base; spikes nuraerous, approximate on the elongate axis, spreading, short-pedicellate, falling entire, bearing a single spikelet, the axis prolonged beyond the spikelet in a rather slender bristle; glumes subacute, glabrous or scabrous, the first about 3 mm. long, the second about 5 mm. long; fertile lemma acuminate, awnless, 5-7 mm. long, glabrous or sparsely pilose; rudiment narrow, inconspicuous, not cleft, the body about 2 mm. long, the awns 6-10 mm. long, scabrous.
Type locality; Guanajuata, Mexico {Humboldt &* Bonpland).
Distribution: Dry calcareous rocky hills and open ground, central Mexico to Guatemala.