558 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



120. LEERSIA Swartz 

 {Homalocenchrus Mieg.) 



Spikelets 1-flowered, strongly compressed laterally, disarticulating from 

 the pedicel; glumes wanting; lemma chartaceous, broad, oblong to oval, 

 boat-shaped, usually 5-nerved, the lateral pair of nerves close to the margins, 

 these and the keel often hispid-ciliate, the intermediate nerves sometimes 

 faint; palea as long as the lemma, much narrower, usually 3-nerved, the keel 

 usually hispid-ciliate, the lateral nerves close to the margins, the margins 

 firmly held by the margins of the lemma; stamens 6 or fewer. Perennials, 

 usually with creeping rhizomes, flat, scabrous blades, and mostly open panicles. 

 Type species, Leersia oryzoides. Named for J. D. Leers. 



Spikelets broadly oval, 3 to 4 mm. wide 1. L. lenticularis. 



Spikelets elliptic, not more than 2 mm. wide. 



Panicle narrow, the branches ascending or appressed 4. L. hexandra. 



Panicle open, the capillary branches finally spreading. 



Spikelets glabrous, about 2 mm. long; culms tufted, erect; rhizomes wanting. 



5. L. MONANDRA. 



Spikelets hispidulous; culms decumbent at base; rhizomes present. 

 Lower panicle branches solitary; spikelets 3 mm. long, 1 mm. wide. 



3. L. VIRGINICA. 



Lower panicle branches fascicled; spikelets 5 mm. long, 1.5 to 2 mm. wide. 



2. L. ORYZOIDES. 



1. Leersia lenticularis Michx. 

 Catchfly grass. (Fig. 808.) Culms 

 straggling, 1 to 1.5 m. tall, with 

 creeping scaly rhizomes; sheaths sca- 

 brous at least toward the summit; 

 blades lax, 1 to 2 cm. wide; panicle 

 open, drooping, 10 to 20 cm. long, 

 the branches ascending or spreading, 

 naked below, branched above, branch- 

 lets bearing closely imbricate spike- 

 lets along one side; spikelets pale, 

 broadly oval, very flat, 4 to 5 mm. 

 long, sparsely hispidulous, the keels 

 bristly ciliate. % — Ditches and 

 swamps, Maryland to Minnesota, 

 south to Florida and Texas. 



2. Leersia oryzoides (L.) Swartz. 

 Rice cutgrass. (Fig. 809.) Culms 

 slender, weak, often decumbent at 

 base, 1 to 1.5 m. tall, with slender 

 creeping rhizomes; sheaths and blades 

 strongly retrorsely scabrous, the 

 blades mostly 8 to 10 mm. wide; 

 panicles terminal and axillary, 10 to 

 20 cm. long, the flexuous branches 

 finally spreading, the spikelets more 

 loosely imbricate than in L. lenti- 

 cularis; spikelets elliptic, 5 mm. long, 

 1.5 to 2 mm. wide, sparsely hispidu- 

 lous, the keels bristly ciliate; axillary 

 panicles reduced, partly included in 

 the sheaths, the spikelets cleistog- 



Figure 808. — Leersia lenticularis, X 1. (McDonald 

 68, 111.) 



amous. % — Marshes, river banks, 

 and wet places, often forming a zone 

 around ponds and lakes, Quebec and 

 Maine to British Columbia and east- 

 ern Washington south to northern 

 Florida, Texas, Colorado, Arizona, 

 and southeastern California; Europe. 

 The late cleistogamous phase has 

 been described as L. oryzoides forma 

 inclusa (Wiesb.) Dorfl. 



3. Leersia virginica Willd. White- 

 grass. (Fig. 810.) Culms slender, 



