MANUAL OF THE GRASSES OF THE UNITED STATES 411 



thin pericarp (easily removed when wet). Spreading annual, with 

 capitate inflorescences in the axils of a pair of broad spathes, these 

 being _ enlarged sheaths with short rigid blades. Type species, 

 Crypsis aculeata. Name from Greek krupsis, 

 concealment, alluding to the partially hidden 

 inflorescence. 



1. Crypsis aculeata (L.) Ait. (Fig. 856.) 

 Freely branching, prostrate, the mats 30 cm in 

 diameter, or often depauperate, 1 to 2 cm wide ; 

 blades small, sharp-pointed; heads numerous, 

 4 to 5 mm high, the spathes broader than long, 

 then blades spreading; glumes about 3 mm 

 long, minutely hispid; lemma about as long as the glumes, sca- 

 brous on the keel, o — Overflowed land of the interior valley, 

 California; introduced from Europe. 



79. HELEOCHLOA Host 



Spikelets 1-flowered, the rachilla disarticulating above the glumes; 

 glumes about equal, narrow, acute; lemma broader, thin, 1-nerved, a 

 little longer than the glumes; palea nearly as long as the lemma, 

 readily splitting between the nerves. Low spreading annuals with 



Figure 855.— Distribution of 

 BlepharoneuTon tricholepis. 



Figure 856.— Crypsis aculeata. Plant, X 14; glumes and floret, X 10. (Brandegee, Calif.) 



oblong, dense, spikelike panicles, the subtending leaves with inflated 

 sheaths and reduced blades. Type species, Heleochloa alopecuroides. 

 Name from Greek helos, marsh, and chloa, grass, alluding to the 

 habitat of the type species. 



1. Heleochloa schoenoides (L.) Host. (Fig. 857, A.) Culms 

 tufted, branching, erect to spreading and geniculate, 10 to 30 cm long; 

 sheaths often somewhat inflated; blades flat, with involute slender 

 tips, mostly less than 10 cm long, 2 to 4 mm wide; panicle pale, 1 to 4 cm 



