often rudimentary. 



A small genus of the warmer parts of the world. 



1. Racemes flattened, tardily disarticulating; first glume of sessile spikelet smooth 

 1. M. altissima. 



I. Racemes nearly cylindric, readily disarticulating at maturity; first glume of 

 sessile spikelet marked with pits or wrinkles 2. M. rugosa. 



1. Manisuris altissima (Poir.) Hitchc. 



Perennial; culms ascending from a long creeping base, compressed and 2-edged, 

 4-8 dm. long, freely branching toward the ends; blades flat, 3-8 mm. wide; flower- 

 ing branches often short and fascicled; racemes 3-5 cm. or sometimes 1 dm. long, 

 compressed; pedicel free or partly adnate to the rachis joint; sessile spikelet 5-7 

 mm. long, the keels of the first glume very narrowly winged toward the apex; 

 pedicellate spikelet 5-6 mm. long, acute. 



Rare in coastals. Tex., where repeatedly introd. in ponds, ditches and on edge 

 of water in the Rio Grande, spring-fall; warmer parts of the world, introd. in Am. 



2. Manisuris rugosa (Nutt.) O. Ktze. 



Perennial; culms mostly rather stout, 7-12 dm. tall, freely branching; sheaths 

 compressed-keeled; blades commonly folded, 3-8 mm. wide; flowering branches 

 often numerous; racemes 4—8 cm. long, partly included in brownish sheaths; rachis 

 joint and pedicel contracted in the middle; sessile spikelet 3.5-5 mm. long, the 

 first glume strongly and irregularly transversely ridged, the keels narrowly winged 

 toward the summit. 



Infrequent in open woodlands on low often moist or wet sandy loam, in wet 

 savannahs and wettish pine woods, in e. and s.e. Tex., summer-fall; Coastal 

 States, Va. to Tex.; Ark. 



61. Tripsacum L. 



A small American genus of which we have one species. 

 1. Tripsacum dactyloides (L.) L. Eastern gamagrass. Fig. 173. 



Very robust perennial, usually 15-30 dm. tall, often with rhizomes, glabrous 

 throughout; blades elongate, 1-2 cm. broad, flat; inflorescence 15-25 cm. long, 

 terminal, subdigitate group of a few androgynous spikelike racemes, each with a 

 few lower solitary pistillate fertile spikelets at the base and many paired staminate 

 spikelets above; pistillate spikelets 7-10 mm. long, occasionally subtended by a 

 rudimentary pedicel, arranged on opposite sides at each joint of the thick hard 

 articulate lower part of the rachis, sunken in niches of the sculptured rachis, con- 

 sisting of one perfect floret and a sterile lemma; first glume coriaceous, nearly 

 infolding the spikelet, fitting into and closing the hollow of the rachis; second 

 glume similar to the first but smaller, infolding the remainder of the spikelet; 

 sterile and fertile lemmas and palea very thin and hyaline; staminate spikelets 

 7-1 1 mm. long, paired and 2-flowered; glumes firm, acute; lemma and palea 

 hyaline. Incl. var. occidentale Cutler & Anders. 



In marsh-meadows, wet grasslands, seepage areas, in wet mud along streams and 

 about ponds, in Okla. (LeFlore Co.), frequent in scattered parts of Tex. but more 

 common in the e. half, very rare in the Plains Country, summer-fall; W.I.; e. U.S., 

 Coah., N.L., Tarn., S.L.P. 



Fam. 25. Cyperaceae Juss. Sedge Family 



Herbs with tristichous leaves and often triangular stems; blades grasslike, often 

 long and linear or gradually tapered; inflorescences diverse; florets often borne 

 grouped into spikelets, each floret subtended by a single abaxial scale (apparently 



341 



