median distal portion purplish (midrib paler) and membranous, the median proxi- 

 mal portion whitish, the margins white-hyaline; bristles somewhat variable, in our 

 specimens much reduced or usually absent; styles 3-branched; achenial body 0.5- 

 0.6 mm. long, obovoid, trigonous (angles not very prominent, sides convex), 

 pearly-white, lustrous, smooth; tubercle 0.05-0.1 (-0.15) mm. long, depressed- 

 pyramidal, buffy-white, slightly constricted basally. E. Brittonii Small, E. LundelUi 

 Svens. 



On sandy loams, in mud and shallow water of ponds and streams, and depres- 

 sions in savannahs, frequent in s.e. Tex., infrequent in e. Tex., spring-fall; coastal 

 areas, Conn, and N.J. to Tex.; also Tenn. and Ind. 



26. Eleocharis albida Torr. Fig. 201. 



Rhizomatous perennial; rhizomes extensive, 1-2 mm. thick, orangish-brown; 

 culms tufted at intervals along the rhizome, 5-30 cm. long, about 1 mm. thick, 

 erect, essentially terete, stramineous or basally slightly pinkish; sheaths apically 

 truncate or shortly oblique and firm but membranous, basally often pinkish to 

 red; spikelets ovoid to ovoid-cylindric, 5-16 mm. long, of 30 to 90 flowers, rarely 

 proliferating; scales broadly ovate, subcartilaginous medially, firm-membranous 

 marginally, stramineous, shiny; bristles 5 to 8, when mature reddish-brown, some 

 often surpassing the achenial body, others half as long; style 3-branched; achenial 

 body broadly obovoid, 0.8-1 mm. long, trigonous (the 2 inner angles sharper and 

 more definite than the abaxial one, the faces only slightly convex), maturing 

 through shades of olive-whitish to brownish-olive and finally to a rich dark- 

 chocolate-brown, lustrous; tubercle varying from conic to globular, 0.15-0.3 

 mm. long, paler than the body at maturity, constricted basally. 



Frequent in moist perhaps brackish sand and on lake margin and in water, in 

 coastal parts of Rio Grande Plains and s.e. Tex., spring-summer; coastal areas, 

 Md. to Mex.; Berm, 



27. Eleocharis elongata Chapm. Fig. 202. 



Culms very slender, usually less than 1 mm. wide, elongate, 5-8 dm. long, often 

 floating on the surface of the water, flattened or obscurely angled; roots fibrous; 

 stolons abundant, brown or straw-colored, elongate, with culms rising from the 

 nodes; spikelets 1-1.5 cm. long, about 2 mm. wide, acute; style 3-branched; 

 stamens 3; scales linear, obtuse, 3.5 mm. long, striate, greenish, conspicuously 

 broadened with brown just within the hyaline margin; achenes 1.5 mm. long 

 including the style base, triangular, light-green, obovate (the inner face broadest, 

 with about 12 rows of coarse transversely linear cells), abruptly narrowed at the 

 summit to a short acute neck one-fourth the width of the achene from which 

 rises the short acute deep-brown style base; bristles 6 or 7, equalling the achene, 

 greenish, prominently toothed. 



In quiet water of lakes and ponds in Tex. (Hardin Co.); Fla. to Tex. 



28. Eleocharis tenuis (Willd.) Schult. var. verrucosa (Svens.) Svens. 



Rhizomatous perennial; rhizomes 1-2 mm. thick, scaly-fibrous, castaneous- 

 fuscous; culms tufted at intervals along the rhizomes, 15-50 cm. long, 0.2-0.3 

 mm. thick, weakly ascending, 4- or 5-sulcate or simply angled; sheaths basally 

 purplish-red, apically firm, truncate to very slightly oblique, usually with a 

 minute mucro; spikelets oblong or narrowly ovoid to lance-ovoid, 3-9 mm. long, 

 of 20 to 40 flowers; scales ovate to obovate, obtuse, about 2 mm. long, with a 

 greenish or stramineous midrib and firm castaneous to purplish-black sides, 

 marginally very narrowly scarious; bristles 2 or 3, promptly deciduous, very short; 

 styles 3-branched; achenial body broadly obovoid to suborbicular, distinctly 

 trigonous, 0.6-0.8 mm. long, ripening through shades of ivory to greenish-olive, 

 surficially minutely but pronouncedly warty or pitted in vertical lines; tubercle 



393 



