GENERA OF GRASSES OF THE UNITED STATES. O17 
Syntherisma is included in Panicum by some botanists and in Pas- 
palum by others. It differs from both in the cartilaginous rather 
than indurate fruit and in 
the flat, white, hyaline 
margins of the lemma. 
Our commonest species 
is Syntherisma sanguinalis 
(L.) Dulac (Digitaria 
sanguinalis Scop.) (fig. 
130), usually called crab- 
grass. This is a decumbent 
or prostrate annual, usually 
more or less purple, with 
hispid sheaths, flat blades, 
few to several slender digi- 
tate or subdigitate spikes 
or racemes, and a narrowly 
' winged rachis, the first 
glume minute. Crab-grass 
is a native of the Old 
World, but is now widely 
distributed in tropical 
America, and is common in 
_ cultivated soil throughout 
the eastern and southern 
part of the United States. 
It is often a bad weed in 
lawns. In the Southern - 
States, where crab-grass 
produces an abundant 
growth in the late summer 
on the fields from which 
; crops have been gathered, 
Bie, 130.—Crab-grass, Syntherisma sanguinalis. jt, ig ytilized for forage and 
Plant, ~ 4; two views of spikelet and fertile , i 
floret, % 10, is sometimes cut for hay. 
