Eleocharis retroflexa

Plants annual, tufted, mat-forming, often stoloniferous, sometimes entirely vegetative; rhizomes absent. Culms erect, ascending or arching, pentagonal, sulcate, 1.5-10 cm × 0.2-0.3 mm [larger], soft. Leaves: distal leaf sheaths persistent or disintegrating, pale brown to green, red-spotted [mostly red-brown], membranous; apex acuminate. Spikelets: basal spikelets usually present, bisexual; often proliferous, ellipsoid or obovoid, laterally compressed, 1.7-3.9 × 1.2-2 mm, apex acute; proximal scale empty or with a flower, deciduous, amplexicaulous, similar to floral scales (sometimes 2.4-2.9 mm); subproximal scale with a flower; floral scales clearly distichous, 2-6 [or more], 4-6 per mm of rachilla, pale brown [marked red-brown], ovate or elliptic, 1.8-2.5 × 0.8-1.4 mm, membranous, apex rounded to obtuse, midribs green, keeled. Flowers: perianth bristles 6, colorless or pale brown, shorter than achenes; spinules not evident at 45X; stamens 3; anthers (0.55-)0.7 mm; styles 3-fid. Achenes stramineous (to cream), obovoid, trigonous or subterete, not compressed, angles prominent, 0.8 × 0.5-0.55 mm, apex not constricted proximal to tubercle, coarsely cancellate or honeycomb-reticulate at 10-15X. Tubercles red-brown, pyramidal, trigonous, proximally clearly to obscurely 3-lobed, lobes decurrent on achene angles, 0.3-0.35 × 0.3-0.4 mm.

Fruiting summer. Freshwater ponds, stream banks, marshes, sandy or muddy soils; 0-10 m; Ala.; Mexico; West Indies; Bermuda; Central America; South America; Asia (including Indonesia); Pacific Islands; Australia.

We have seen only one collection of Eleocharis retroflexa from the flora area (Mobile, Alabama, in 1896, US). Other populations are likely in the United States Gulf States. The broad-shouldered, strongly sculptured achenes, trilobed, decurrent tubercles, and basal spikelets are distinctive.