MANUAL OF THE GRASSES OF THE UNITED STATES 697 



Name from Latin seta, a bristle, alluding to the numerous bristles of 

 the inflorescence. The species are, in general, palatable and nutri- 

 tious. A few species, especially S. macrostachya, form an appreciable 

 part of the forage on southwestern ranges. Primitive peoples have 

 cultivated S. itcdica, Italian or foxtail millet, since prehistoric times. 

 The seed has been found in early remains such as those of the Swiss 

 lake dwellings of the stone age. In America the species is used for hay. 

 Another species, S. palmifolia, is cultivated for ornament in green- 

 houses. 



Bristles below each spikelet numerous, at least more than 5. Panicle dense, 

 cylindric, spikelike. 



Plants annual 1. S. LTTTESCENS. 



Plants perennial 2. S. GENICULATA. 



Bristles below each spikelet 1, or, by the abortion of the spikelets, 2 or 3. 



Bristles more or less retrorsely scabrous (antrorsely in var. ambigua) 



3. S. VERTICILLATA. 



Bristles antrorsely scabrous only. 

 Plants perennial. 



Spikelets 3 mm long. 



Blades scabrous 4. S. MACROSPERMA. 



Blades villous 5. S. VILLOSISSIMA. 



Spikelets 2 to 2.5 mm long. 



Blades mostly less than 1 cm wide, often folded; panicles usually loosely 

 or interruptedly spikelike, the branches usually not more than 



1 cm long 6. S. MACROSTACHYA. 



Blades flat, as much as 1.5 cm wide; panicles tapering from near the 



base, the lower branches as much as 3 cm long 7. S. SCHEELEI. 



Plants annual. 



Fertile lemma coarsely transversely rugose. 



Panicle densely cylindric 8. S. CORRUGATA. 



Panicle loosely flowered 9. S. LIEBMANNI. 



Fertile lemma finely cross-lined or nearly smooth. 



Panicle loosely flowered, tapering above 10. S. GRISEBACHII. 



Panicle compactly flowered, sometimes interrupted at base. 



Culms as much as 3 m tall. Bristles 1 to 2 cm long; fertile lemma 



smooth or nearly so 11. S. MAGNA. 



Culms mostly less than 1 m tall. 



Panicle cylindric, tapering above, green; spikelets falling entire. 



12. S. VIRIDIS. 



Panicle lobed or interrupted, often large and heavy, purple or yel- 

 low; fruit deciduous from glumes and sterile lemma. 



13. S. ITALICA. 



1. Setaria lutescens (Weigel) F. T. Hubb. YELLOW BRISTLE- 

 GRASS. (Fig. 1562.) Annual, branching at base; culms erect to 

 prostrate, mostly 50 to 100 cm tall, compressed; sheaths keeled; 

 blades as much as 25 cm long and 1 cm wide, flat, twisted in a loose 

 spiral, villous toward the base above; panicle dense, evenly cylindric, 

 spikelike, yellow at maturity, mostly 5 to 10 cm long, about 1 cm 

 thick, the axis densely pubescent; bristles 5 to 20 in a cluster, the 

 longer 2 to 3 times as long as the spikelet; spikelets 3 mm long; fruit 

 strongly rugose, o Cultivated soil and waste places, New Bruns- 

 wick to South Dakota, south to northern Florida and Texas, occa- 

 sional from British Columbia to California and New Mexico ; Jamaica, 

 at high altitudes (fig. 1563); introduced from Europe; widely distrib- 

 uted in temperate regions. This species has been erroneously 

 referred to S. glauca (L.) Beauv. 



2. Setaria geniculata (Lam.) Beauv. KNOTROOT BRISTLEGRASS. 

 (Fig. 1564.) Resembling S. lutescens but perennial, producing short 

 knotty branching rhizomes as much as 4 cm long ; base of plant slender, 

 why; blades mainly straight (not twisted as in S. lutescens)', bristles 



