558 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



wide, the'upper culm blade distant, reduced; racemes slender, 2 to 5, 

 usually 2 or 3, digitate or some- 

 times approximate on a short 

 axis 3 to 6 cm long, at ma- 

 turity spreading or curved, the 

 rachis flat, winged, about 0.7 

 mm wide; spikelets closely set, 

 elliptic, acutish, minutely pubes- 

 cent, about 1.5 mm long; first 

 glume wanting; second glume 



Figure 1163.— Distribution of 

 Digitaria ischaemum. 



about three-fourths as long as 

 the spikelet; sterile lemma as 

 long as the spikelet, with three 

 distinct nerves and 1 or 2 obscure 

 pairs; fertile lemma acute, dark 

 brown at maturity. 21 — 

 Open pineland in sandy soil, 

 Arkansas (Hamburg), Texas 

 (Buna); tropical America; trop- 

 ical Asia. 



^r 



Figure 1164.— Digitaria floridana. 

 spikelet and fertile floret, X 10. 



Plant, X 1; 

 (Type.) 



6. Digitaria serotina (Walt.) Michx. 

 (Fig. 1165, A.) Creeping, sometimes 

 forming extensive mats; flowering culms 

 ascending or erect, 10 to 30 cm tall; 

 leaves crowded on the creeping culms, 

 the blades short ; sheaths villous ; blades 



2 to 8 cm long, 3 to 7 mm wide ; racemes 

 usually 3 to 5, slen- 

 der, often arcuate, 



3 to 10 cm long, the 

 rachis with thin 

 wings wider than 

 the midrib; spike- 

 lets pale, about 1.7 

 mm long; first 

 glume wanting; 



second glume about one-third as long as 

 the sterile lemma, both finely pubescent ; 

 fertile lemma pale. G — Pastures and 

 waste places, Coastal Plain, North Car- 

 olina to Florida and Louisiana; Phila- 

 delphia (ballast); Cuba (fig. 1166). 



7. Digitaria simpsoni (Vasey) Fer- 

 nald. (Fig. 1167.) Resembling D. 



sanguinalis in habit; sheaths papillose-pilose, those of the inno- 



Figure 1166.— Distribution of 

 Digitaria serotina. 



Figure 1165. — A, Digitaria serotina. 

 Plant, X 1; two views of spikelet and 

 floret, X 10. (Tracy 4653, Miss.) B, D. 

 violascens. Two views of spikelet and 

 floret, X 10. (Hitchcock 9396, Jamaica.) 



