GRIFFITHS—THE GRAMA GRASSES. 859 
1. Cathestecum prostratum Presl. 
Cathestecum prostratum Presl, Rel. Haenk. 1: 295. pl. 42. 1830; Steud. Syn. PI. 
Glum. 1: 201. 1854; Fourn. Mex. Pl. 2: 183. 1881; Hemsl. Biol. Centr. Amer. Bot. 
3: 517. 1885. The following set of characters is drawn from a panicle of the type 
before me: Spikes 4 to 6, small, about 2.5 mm. wide and 4 mm. long, or, including 
the awns of the upper spikelets, 8 mm. long, the rachis prolonged into a bifid awn 
2 mm. long, the lower pair of spikelets always aborted and often reduced to little 
more than the glumes, always short-awned; third spikelet, 2-flowered, with a rudi- 
mentary third floret, the first floret pistillate; glumes narrow, awned, densely hairy, 
the first one of the third floret reduced to a blunt, comparatively wide, nerveless 
scale less than 1 mm. in length; lemma of third spikelet about 4 mm. long, including 
the slightly unequal awns, slightly hairy above, with subulate acute lobes; palet 
Fic. 23.—Cathestecum prostratum. a, Spike; b, uppermost spikelet and prolongation of rachis; c, d, 
lemma and palet of first floret; e, f,lemmaand palet of second floret; g, h, lemma and palet of third floret 
with prolongation of rachilla attached; i, one of lower pair of spikelets; j,k, lemma and palet of first floret; 
1, m, lemma and palet of second floret. a, Scale 5; b-m, scale 7.5. From Pringle 8707. 
2-nerved, with edges incurved, scarcely awned; lemmas of second floret and rudi- 
ment of third, with longer, more prominently hirsute awns and rounded, very deeply 
divided lobes. 
DESCRIPTION. 
A tufted annual, about 20 cm. high; culms variable, erect, geniculate or half- 
prostrate, branching at the nodes; sheaths loosely inclosing the main culm and its 
branches, the ligule reduced to a delicate fringe of flexuous, white hairs; blades few, 
short, 3 to 5 cm. long, 1.5 mm. wide, the upper subulate, about 1 cm. long; panicle 
loosely racemose, with a zigzag flattened axis about 3 cm. long; spikes 4 to 8, trian- 
gular rhomboidal, about 8 mm. long; lower or lateral spikelets about 4 mm, long, the 
central or upper one about 6 mm. long, the two lateral 2-flowered and apparently 
both always staminate, the upper central spikelet consisting of one lower pistillate 
and two upper staminate florets and a club-shaped or bifurcated prolongation of the 
rachilla, about 1 mm. long, behind the palet of the third floret; second glume of each 
