MANUAL OF THE GRASSES OF THE UNITED STATES 



551 



Figure 1153.— Distribution of 

 Anthaenantia rufa. 



glume and sterile lemma about as long as the fruit, 3- to 5-nerved, 

 copiously silky; fertile lemma cartilaginous, lanceolate, acuminate, 

 usually brown, the flat white hyaline mar- 

 gins broad. Perennials with slender erect or 

 ascending racemes, approximate to rather 

 distant along a slender main axis, forming 

 a white to brownish silky panicle. Type 

 species, Trichachne insularis. Name from 

 Greek thrix (trick-), hair, and achne, chaff, 

 alluding to the silky spikelets. 



Trichachne insularis is not relished by cattle, 

 hence the name sourgrass by which it is called in the West Indies; 

 T. californica is a constituent of the ranges of the Southwest, and 

 furnishes fair forage. 



Fruit 4 mm long; spikelets tawny-villous 1. T. insularis- 



Fruit 3 mm or less long (rarely 3.5 mm) ; spikelets white-villous. 



Spikelets long-silky, the hairs exceeding the spikelet; fruit 3-3.5 mm long. 

 Panicle branches stiffly ascending or spreading, comparatively few flowered; 



fruit oblong-lanceolate, gradually pointed 3. T. patens. 



Panicle branches appressed, densely flowered; fruit obovate, abruptly 



pointed, the point scarcely indurate 2. T. californica. 



Spikelets short-silky, the hairs not exceeding the spikelet; fruit 2.4 mm 

 long 4. T. HITCHCOCKII. 



1. Trichachne insularis (L.) Nees. Sourgrass. (Fig. 1155.) Culms 

 suberect from a hard scaly hairy swollen base, 1 to 1.5 m tall; leaves 



numerous; the sheaths sparsely hirsute; blades 

 elongate, 8 to 15 mm wide; panicle 15 to 30 cm 

 long, the slender racemes mostly 10 to 15 cm 

 long, somewhat nodding; spikelets approximate, 

 excluding the hairs about 4 mm long, the tawny 

 hairs much exceeding them. % (Valota insu- 

 laris Chase.) — Low open ground and waste 

 nG ™X^SriS onof P laces » Florida, Alabama (Mobile), and south- 

 ern Texas; Mexico, West Indies to Argentina. 



2. Trichachne californica (Benth.) Chase. Cottontop. (Fig. 

 1156.) Culms erect from a knotty swollen felty-pubescent base, 40 

 to 100 cm tall; leaves numerous, the sheaths glabrous to sparsely 

 pilose; blades mostly less than 12 cm long, 3 to 5 mm wide, from 

 nearly glabrous to densely puberulent; panicle mostly 5 to 10 cm 

 long, the few racemes usually 3 to 5 cm long, occasionally longer, 

 erect or nearly so; spikelets approximate, excluding the hairs 3 to 

 4 mm long, the white to purplish hairs much exceeding them, often 

 spreading, the middle internerves of the sterile lemma glabrous. 

 % (T. saccharata Nash.) — Plains and dry open ground, Texas to 

 Colorado, Arizona, and Mexico (fig. 1157). 



3. Trichachne patens Swallen. (Fig. 1158.) Culms tufted, 

 erect, 40 to 90 cm tall; sheaths more or less papillose-pilose, the 

 lowermost densely felty pubescent; blades 5 to 15 cm long, 1 to 

 4 mm wide, scabrous; panicle 10 to 18 cm long, the racemes stiffly 

 ascending or spreading; spikelets remote, 4 mm long, densely silky, 

 the hairs exceeding the spikelet; fruit 3 mm long, acute. ^% — 

 Dry fields, prairies, and roadsides, Texas. 



4. Trichachne hitchcockii (Chase) Chase. (Fig. 1159.) Culms tufted 

 and branching at base, leafy below, slender, 30 to 50 cm tall; sheaths 



