MANUAL OF THE GRASSES OF THE WEST INDIES 167 
Digitaria laxa Parodi, Physis 9: 13,18. 1928. 
Culms in large tufts, decumbent at base, 1 to 2 m tall; sheaths tuber- 
culate-hispid; blades flat, glabrous or nearly so, 5 to 20 cm long, 5 to 
15 mm wide; panicle 15 to 25 cm long, the numerous rather slender 
racemes usually 15 to 20 cm long, widely spreading; spikelets narrowly 
lanceolate, acuminate, rather sparsely silky pilose, 4 to 5 mm long. 
ee stiff hairs of the sheaths break off in handling and penetrate the 
skin. 
Open moist ground, southern West Indies to Paraguay. 
WINDWARD isLtaNnps: Grenada, Broadway 1782. 
TrinipapD: Pitch Lake, Hitchcock 10084 (Amer. Gr. Nat. Herb. 553). 
Cedros, Hitchcock 10143. San Fernando, Bot. Gard. Herb. 3374. 
Port-of-Spain, Hirchcock 9954. 
Toxsaco: Hitchcock 10246; Broadway 4851. 
CE DIGTRARUA EH eist.=Scop., Kh Cam ed 72. 1: 52277 1702 
~ CRABGRASS 
(Syntherisma Walt., Fl. Carol. 76. 1788) 
Spikelets solitary or in twos or threes, subsessile or short-pediceled, 
alternate in two rows on one side of a 3-angled winged or wingless 
rachis; spikelets lanceolate or elliptic, plano-convex; first glume 
minute or wanting; second glume equaling the sterile lemma or shorter; 
fertile lemma cartilaginous, the hyaline margins pale. Erect or 
prostrate annuals or perennials, the slender racemes digitate or some- 
what scattered, but aggregate along the upper part of the culms. 
Rachis wing-margined, the green wings as wide as the whitish midrib or wider. 
Rinstealumesnvalleugsevident== 6 ye = ae oe 1. D. SANGUINALIS. 
First glume obsolete or wanting. 
Rachis sparsely beset with spreading long hairs____-_- 2. D. HORIZONTALIS. 
Rachis with no long hairs. 
Pedicels with a ring of short stiff hairs at summit; spikelets with stripes of 
dense:capiteliate hairs. o- Se es ee es 3. D. ARGYROSTACHYA. 
Pedicels not hairy at summit. 
Second glume about half as long as the spikelet. Plant creeping and 
ROOMPnAL UME OGESs 15 ey iim s Ancien. eit at 4, D. SEROTINA. 
Second glume as long as the spikelet. 
Syolkeletse 2 cmmprOn eat ei oa A 6. D. ISCHAEMUM. 
Spikelets 1.5 mm long. 
Culms erect or decumbent at base.__________- 5. D. VIOLASCENS. 
Culmeitormine long stolons!) 2 ga. = a gees 7. D. LONGIFLORA. 
Rachis not winged or the margin much narrower than the midrib. 
Spikelets glabrous or nearly so. 
Spikelets 1.5 mm long; second glume shorter than the spikelet; obtuse. 
10. D. CURVINERVIS. 
Spikelets 2.5 mm long; second glume as long as the spikelet, acute. 
1 D. EKMANII. 
Spikelets pubescent. 
Spikelets 1.5 mm long (disregarding the hairs extending beyond the end). 
Hairs on the spikelet extending beyond the apex as a stiff brownish 
| SPRUASH DUNT rey 0) a eae Re ea ee MAE eds aii 11. D. ARGILLACEA. 
Hairs on spikelet not extending beyond the spikelet as a brushlike tip. 
9. D. PANICEA. 
Spikelets 2 mm long. 
Hairs extending beyond the spikelet as a short brushlike tip. 
12. D. PINETORUM. 
Hairs not extending beyond the spikelet as a brushlike tip_8. D. viLLosa. 
