GRIFFITHS THE GEAMA GRASSES. 



359 



1= Cathestecum prostratum Presl. 



Cathestecum prostratum Presl, Rel. Haenk. 1 : 295. pi. 42. 1830; Steud. Syn. PL 

 Glum. 1 : 201. 1854; Fourn. Mex. PI. 2: 133. 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 



Fig. 23.— Cathestecum prostratum. a, Spike; 6, uppermost spikelet and prolongation of rachis; c, d, 

 lemma and palet of first floret; e, f, lemma and 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; 

 I, m, lemma and palet of second floret, a, Scale 5; 6-ra, 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 



