medially chartaceous, laterally membranous and marginally hyaline; bristles usually 

 reduced and essentially obsolete in our plants, most of which are of the var. 

 anachaeta (Torr.) Svens.; stamens 3; style 3-branched; achenial body ovoid to 

 obovoid, trigonous, 0.8-1 mm. long, passing through shades of gray to fuscous or 

 black at maturity, smooth, usually somewhat shiny; tubercle conic-trigonous, 

 much narrower than the body of the achene and confluent with it, scarcely 

 differentiable except under high magnification, 0.1-0.2 mm. long. Scirpus nanus 

 Spreng. (non-Poir.), E. membranacea (Buckl.) Gilly. 



In mud and shallow water of lakes, ponds and stream banks, occasionally in 

 salt marshes, infrequent to locally abundant, essentially throughout Tex., in Okla. 

 (Kay, Stephens, Grady, San Miguel and Garvin cos.), N.M. (Chaves and Eddy 

 cos.) and Ariz. (Navajo Co.), spring-fall; var. parvula is widespread in Eur., 

 N. Afr., the Near East and N.A.; var. anachaeta is scattered in w. N.A. 



20. Eleocharis pauciflora (Lightf.) Link. 



Perennial with filiform rhizomes bearing small leafy tubers; culms capillary, 

 grooved, erect, 7-14 cm. tall or sometimes 40 cm. tall, usually less than 1 mm. 

 thick, not proliferous; basal leaf sheaths 2-3 cm. long, truncate; spikelets 4-7 

 mm. long, ovate 2- to 7-flowered; scales lanceolate, acuminate, purplish-brown 

 bristles 2 to 6, shorter than to as long as or longer than the achene; style trifid; 

 achene trigonous, the surface finely reticulate, yellowish-brown, about 2 mm. long; 

 tubercle a subulate beak merging into the dark base of the style. 



Boggy or otherwise wet places at high elevations in the mts., tolerant of salt 

 and alkali, Ariz. (Apache and Coconino cos.), circumboreal, e. to 111. and N. J. 



21. Eleocharis rostellata (Torr.) Torr. Fig. 198. 



Tufted perennial with short often erect rhizomes to 5 mm. thick; culms 25-80 

 (-150) cm. long, flattened (1-1.4 mm. thick in the broader dimension), on each 

 side usually 3- or 4-costate, wiry, tough, erect or the more elongate ones arching 

 and taking root as the spikelet touches the ground, thus stoloniform; sheaths 

 firm, apically slightly oblique; spikelets lanceolate, acute, 8-17 mm. long, 2.5-4.5 

 mm. thick, with 12 to 30 flowers; scales ovate, 3-3.5 mm. long, the upper ones 

 more acute than the lower, medially rigid and with a strong stramineous midrib, 

 passing laterally through chartaceous to membranous texture and in color through 

 shades of brown to pale-brown or stramineous marginally; bristles firm, regularly 

 serrulate, pale-brown, about equaling the tubercle; style 3-branched; achene body 

 obscurely trigonous or turgidly plano-convex, obovoid, brownish, shiny, 1.5-1.7 

 mm. long, apically narrowed and merging with the tubercle; tubercle oblong or 

 stelelike, 0.7-1 mm. long, 0.3-0.4 mm. thick basally (at attachment but narrower 

 most of the length). 



Mud in upland areas, springs, alkaline marshes and seeping wet meadows, in 

 Okla. (Texas Co.), frequent in Tex. Plains Country, infrequent on Edwards 

 Plateau, N. M. (Otero, DeBaca, San Juan, Valencia, Sandoval, Eddy and Grant 

 COS.) and Ariz. (Coconino, Yavapai, Graham, Cochise and Santa Cruz cos.), 

 summer-fall; N.S. and Me. to Fla., inland in Ont. to N.J., Mich., Wise, 111., Kan., 

 Okla., Tex., Coah., B.C. to Wyo., Ut., Cahf., N.M.; Berm, Cuba, Hisp., n. Mex., 

 mts. of Ecu. and Arg. 



22. Eleocharis tortilis (Link) Schult. Fig. 199. 



Tufted perennial; rhizomes ascending, 2-3 mm. thick; culms 15-50 cm. long, 

 0.5-1 mm. thick, usually flattened or irregularly 3-costate and -sided, often twisted, 

 wiry, grayish to yellowish; sheaths grayish or yellowish, shortly oblique and acute 

 or blunt, firm; spikelets ovoid to lance-ovoid or cylindric-ovoid, 6-14 mm long, 

 of 13 to 38 flowers; scales ovate to suborbicular, about 3 mm. long, blunt, firm 

 (subcartilaginous medially to chartaceous marginally), yellowish or grayish-strami- 



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