8d. ELEOCHARIS R. Brown subg. LIMNOCHLOA (Palisot de Beauvois ex T. Lestiboudois) Torrey, Ann. Lyceum Nat. Hist. New York. 3: 296. 1836.
M. Socorro González-Elizondo
Limnochloa Palisot de Beauvois ex T. Lestiboudois, Essai Cypér., 41. 1819; Eleocharis ser. Mutatae Svenson
Plants perennial, when submerged sometimes with spikelets proliferating. Rhizomes present, creeping, sometimes with apical tubers. Culms 16–115 cm × 0.5–8.5 mm, spongy with transverse septa incomplete or often hollow with complete transverse septa. Spikelets cylindric to narrowly ellipsoid, terete, often as wide as their culms, (6–)9–75 mm; rachilla with proximal internodes about the same thickness and length as internodes in middle of spikelet; proximal scale empty or rarely subtending a flower; floral scales ca. 4–220 per spikelet, spiraled, 3–8 mm, with 15 or more prominent to obscure, close, longitudinal veins, papery to cartilaginous. Styles 3-fid, or 3-fid and 2-fid. Achenes biconvex, sometimes compressed trigonous, sometimes distally constricted into a distinct, thick neck, 1.4–3 mm, markedly (to obscurely) sculptured, each face usually with 10–40 longitudinal rows of enlarged cells, sometimes nearly smooth. Tubercles distinct from achenes in color, texture and form, or sometimes merging with achene apex, often dorsoventrally greatly compressed.
Species ca. 21 (7 in the flora): tropical, subtropical (and warm temperate) areas worldwide.
Eleocharis dulcis (Burman f.) Trinius, the Chinese water-chestnut, is sometimes cultivated in the southeastern United States for the edible tubers produced by some cultivars. According to D. B. Ward and E. M. Leigh (1976), it is also occasionally grown as an aquarium or fish-pond novelty; it apparently does not persist or escape. Because E. dulcis is a widely distributed aquatic weed in Asia, it might escape from cultivation in North America as well. It is most similar to E. interstincta and E. equisetoides; it has completely smooth achenes. Eleocharis fistulosa (Poiret) Link (= E. acutangula (Roxburgh) Schultes) was cited from North America by H. K. Svenson (1957) and D. S. Correll and H. B. Correll (1972) on the basis of Runyon’s specimens from Texas, which belong to E. obtusetrigona (Lindley & Nees) Steudel.