FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



hairs; empty glumes above the floret 3; first 1.5 mm. long, broad, 

 truncate and with a wide-scarious margin, minutely bidentate, bearing 

 a scabrous awn 1.5 long, and subtending an empty narrow palea i mm. 

 long; second and third glumes like the first but smaller and awnless, 

 the rachilla produced into a curved point .2-. 3 mm. long, all enfolded 

 or partly so in first empty glume. Grain reddish brown, ellipsoid, 

 .5 -.65 x 1.4 mm. ; in section depressed trilateral. 



Hab. Merida, Aug. 3, 1865, Schott 383; Calcehtoh, March n,, 

 1890, Stone 274 (in Herb. Phila. Acad. Sci.); Chichankanab, Gaunter 

 1342, 2311, Izamal 2476. 



Chloris elegans H. B. K. Nov. Gen. et Sp. PL 1:166. 



Inflorescence short exserted or sometimes included at the base, of 

 5-10 spikes, 4-6.5 cm. long, 7-8 mm. wide, with 40-65 ascending spike- 

 lets; rachis 3-angled, hirsute, internodes i mm. long. Spikelets 

 23x9-12 mm. (including awns), tawny or pale, with a few long 



hairs on the very short pedicel. 

 First and second glumes lanceolate,, 

 acute, hispidulous on the keel, first, 

 2 mm., second 3 mm. long, with a. 

 scabrous awn .6 mm. ; floral glume 3, 

 mm., naviculate, 3-nerved, with a 

 tuft of stiff hairs at the base and 

 densely ciliate on the margins above 

 with stiff white hairs 2 mm. long, 

 bearing a slightly divergent, scabrous 

 awn, 8-10 mm. long, from the bi- 

 dentate apex; palea equal in length, 

 rounded at the summit, minutely cil- 

 iate on the two nerves; empty glume 

 above the floret 2 mm., truncate, bi- 

 dentate, bearing a scabrous awn 6-7 

 mm. long, the rachilla terminated by a second rudimentary glume 

 enclosed in the first. Grain light reddish brown, ellipsoid .5 -.55 x 1.7 

 mm. ; in section compressed trilateral, the angles rounded and facets 

 convex. 



Hab. Sacalum, Sept. 18, 1865, Schott 632; "Abundant on stone 

 walls near Izamal, 18 inches high," Gaunter 1085 (Chloris barbata 

 Field Col. Mus. Bot. 1:351), 2172. 



Yucatan specimens have awns and empty glumes longer than typical- 



BOUTELOUA Lag. Var. Cienc. 2:pt. 4, 134. 



Spikelets i-2-flowered, numerous, or rarely i or 2, crowded and 

 closely sessile in 2 rows along one side of a continuous flattened 

 rachis which usually projects beyond the spikelets; rachilla articu- 

 lated above the empty glumes and bearing a 3-awned staminate or 

 neuter floret above the single perfect lower one. Empty glumes 2,. 

 floral glume 3-nerved, usually 3-awned. Grain elongated, free. 

 Stamens 3. 



Spike of a solitary spikelet Tricena. 

 Spike of several to many spikelets: 



Rachis entire at summit, first glume lanceolate Americana. 



Rachis bifid at summit, first glume subulate disticha. 



