MANUAL OF THE GRASSES OF THE UNITED STATES 



563 



on an axis 1 to 4 cm long, mostly suberect, 7 to 12 cm long, pale, 

 sometimes naked at base, the rachis flat- triangular; spikelets narrowly 

 lanceolate, acute, 2.8 to 3.5 mm long; first glume minute or obsolete; 

 second glume and sterile lemma equal, sparsely to densely villous on 

 the internerves, the lemma glabrous on the middle internerves; fertile 

 lemma acuminate, usually a little shorter than the spikelet, pale at 

 maturity. % —Sand dunes and sandy prairies along the coast, 

 southern Texas. 



122. LEPTOLOMA Chase 



Spikelets on slender pedicels; first glume minute or obsolete; 

 second glume 3-nerved, nearly as long as the 5- to 7-nerved sterile 

 lemma, a more or less prominent stripe 

 of appressed silky hairs down the inter- 

 nerves and margins of each, the sterile 

 lemma empty or enclosing a minute 

 nerveless rudimentary palea; fertile 

 lemma cartilaginous, elliptic, acute, 

 brown, the delicate hyaline margins en- 

 closing the palea. Branching perenni- 

 als with brittle culms, felty pubescent at 

 base, flat blades, and open or diffuse 

 panicles, these breaking away at matu- 

 rity, becoming tumble weeds. Type 

 species, Leptoloma cognatum. Name 

 from Greek leptos, thin and loma, border, 

 alluding to the thin margins of the 

 lemma. 



1. Leptoloma cognatum (Schult.) 

 Chase. Fall witchgrass. (Fig. 

 1178.) Ascending from a decumbent 

 base, often forming large bunches, pale 

 green, leafy; culms 30 to 70 cm long; 

 blades mostly less than 10 cm long, 2 

 to 6 mm wide, rather rigid ; panicle one- 

 third to half the entire height of the 

 plant, purplish and short-exserted at 

 maturity, very diffuse, the capillary 

 branches soon widely spreading, pilose 

 in the axils, the spikelets solitary on 

 long capillary pedicels, narrowly ellip- 

 tic, 2.5 to 3 mm long, abruptly acumi- 

 nate. % (Panicum cognatum Schult., 

 Panicum autumnale Bosc.) — Dry soil 

 and sandy fields, New Hampshire to 

 Minnesota, south to Florida and Texas, west to Arizona (fig. 1179). 

 A fairly palatable grass. 



123. STENOTAPHRUM Trim 



Spikelets embedded in one side of an enlarged and flattened corky 

 rachis tardily disarticulating toward the tip at maturity, the spikelets 

 remaining attached to the joints; first glume small;" second glume 

 and sterile lemma about equal, the latter with a palea or stamina te 



Figure 1177.— Digitaria runyoni. Plant, 

 X 1; spikelet and floret, X 10. (Type.) 



