578 



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



Figure 829. — Digitaria ischaemum. Plant, X 1; spike- 

 let and floret, X 10. (Jones 1761, Vt.) 



three distinct nerves and 1 or 2 

 obscure pairs; fertile lemma acute, 

 dark brown at maturity. O 01 

 — Open pineland in sandy soil, Indi- 

 ana and Kentucky; Georgia and 

 Florida to Arkansas and Texas; 

 tropical America; tropical Asia. 



6. Digitaria serotina (Walt . ) Michx. 

 (Fig. 832.) Creeping, sometimes form- 

 ing 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, slender, 

 often arcuate, 3 to 10 cm. long, the 

 rachis with thin wings wider than 

 the midrib; spikelets 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. O — Pastures 

 and waste places, Coastal Plain, 

 Pennsylvania to Florida and Louisi- 

 ana; Philadelphia (ballast); Cuba, 



Figure 830. — Digitaria floridana. Plant, X 1; spike- 

 let and fertile floret, X 10. (Type.) 



7. Digitaria longiflora (Retz.) Pers. 

 (Fig. 833.) Stoloniferous; culms as- 

 cending, 20 to 40 cm. tall, glabrous; 

 sheaths glabrous; ligule membrana- 

 ceous, 1 mm. long; blades 1 to 4 

 cm. long, 3 to 5 mm. wide, flat, gla- 

 brous; racemes 2 to 4, 3 to 8 cm. 

 long, usually curved, the rachis flat, 

 0.5 to 0.8 mm. wide; spikelets 1.5 

 mm. long, elliptic, minutely pubes- 

 cent. % — Ditches and sand}^ 

 ground, southern Florida; tropical 

 regions of the Old World; introduced 

 in the American Tropics. 



8. Digitaria simpsdni (Vase30 Fer- 

 nald. (Fig. 834.) Resembling D. 

 sanguinalis inhabit ; sheaths papillose- 

 pilose, those of the innovations com- 

 pressed-keeled; blades not more than 

 6 mm. wide, softly pilose; racemes 4 

 to 8, ascending, pale, 8 to 12 cm. 

 long, the triangular rachis narrowl}' 

 margined; spikelets about 3 mm. 

 long; first glume lryaline, obsolete or 

 nearly so; second glume and sterile 

 lemma finely 7- to 9-nerved, glabrous 



