148 Paniceae Digitaria 



Spikelets in an open or contracted panicle. 



Fruiting lemma firm, with flat, hyaline margins; pedicels 3-angled at the 



summit 122. Leptoloma, p. 148. 



Fruiting lemma chartaceous-indurate, the margins inrolled 



129. Panicum, p. 150. 



121-166A. DIGITARIA Heist. Crabgkass 



[Nash. The Genus Syntherisma in North America. Bull. Torrey Bot. 



Club 25 : 289-303. 1898.] 



Lower blades glabrous or nearly so; mature fertile lemmas (fruit) dark brown or 

 black, about 2 mm long. 



Lower sheaths papillose-hirsute ; rachis wingless, about 0.3 mm wide 



1. D. filifomiis. 



Lower sheaths glabrous or with a few straggling hairs; rachis winged, about 1 mm 



w j(je 2. D. Ischaemum. 



Lower blades more or less pubescent; mature fertile lemmas (fruit) light gray to 

 light drab, about 3 mm long 3. D. sanguinalis. 



1. Digitaria filiformis (L.) Koel. (Syntherisma filiforme (L.) Nash.) 

 Map 264. This species is known from only eleven counties and reported 

 from Marshall County. It is very local but common enough where found. 

 My specimens are from very sandy soil in shallow depressions on low, 

 sandy ridges in open woodland, in a moist prairie habitat, and in dry, 

 sandy soil in pastures. 



N. H. to Iowa and Kans., southw. to Fla., Tex., and Mex. 



2. Digitaria Ischaemum (Schreb.) Muhl. (Digitaria humifusa Pers. 

 and Syntherisma Ischaemum (Schreb.) Nash.) Smooth Crabgrass. Map 

 265. Infrequent in the northern part of the state and frequent to com- 

 mon in moist, clayey flats in the southwestern counties. Like the next 

 species, it is found almost everywhere except in dense woodland and very 

 wet soil. It prefers a moist, sandy soil and is found generally in culti- 

 vated fields, pastures, meadows, and waste places and along roadsides. 

 In the southwestern counties in the moist, clayey, fallow fields, it forms 

 dense mats over large areas. 



Nat. of Eurasia; Que. to N. Dak., southw. to S. C, Tenn., and Ark. 



3. Digitaria sanguinalis (L.) Scop. (Syntherisma sanguinalis (L.) 

 Dulac.) Crabgrass. Map 266. This species is a common weed throughout 

 the state, especially in truck gardens, lawns, gardens, and cultivated 

 grounds of all kinds. 



Nat. of Eu. ; throughout the U. S., more common in the East and South. 



122-166C. LEPTOLOMA (has, 



1. Leptoloma cognatum (Schult.) Chase. Map 267. This grass is found 

 in very sandy soil on sand ridges and sandy knolls, usually in fallow fields, 

 along roadsides, and in open woodland. 



N. H. to Minn., southw. to Fla. and Tex., and westw. to Ariz. 



