Rhizomes (1-)1.5-2 mm thick, hard, longer internodes 2 mm, scales decaying to fibers. Culms bluntly angled to smooth, seldom deeply sulcate, to 0.5 mm wide. Leaves: distal leaf sheaths without tooth, or rarely with slender apical tooth to 0.2 mm. Flowers: perianth bristles absent. Achenes dark brown, dark green, or yellow, coarsely (to finely) rugose at 10X, usually coarsely cancellate at 10-20X, 6-10 prominent depressions in each vertical series. Tubercles greatly depressed, rarely pyramidal. 2n = 20.

Fruiting summer. Fresh, often calcareous, shores, wet woods, ditches; 10-600 m; Ala., Ark., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mo., Nebr., Okla., Pa., S.Dak., Tenn., Tex., Va., W.Va., Wis.

Occasionally plants of Eleocharis tenuis var. verrucosa are found mostly submerged.

Harms used a chromosome number as a basis for raising Eleocharis tenuis var. verrucosa to a species (L. J. Harms 1972), but he did not correlate chromosomes with morphology, and I have not located any of his voucher specimens. There are too few chromosome number reports for use in defining taxa in the E. tenuis complex (A. E. Schuyler 1977).

Perennial herb with rhizomes, mat-forming 5 cm - 1 m tall

Leaves: reduced to bladeless sheaths, basal, two per culm, margins fused and enclosing culm, not splitting, dark red (or yellowish brown) basally, green to straw-colored to red upwards, reddish at the apex, membranous, with a blunt to pointed apex that usually lacks the tiny tooth.

Flowers: minute, spirally arranged on the axis of the spikelet, lacking sepals, petals and bristles, subtended by a scale. Stamens three, exserted. Anthers brown, to 1.8 mm long. Pistil one. Style three-cleft.

Fruit: a one-seeded achene, dropping with or before the scales, yellow to dark green or dark brown, under 1 mm long, about 0.5 mm wide, reverse pear-shaped, three-angled, usually coarsely wrinkled (at 10X), with six to ten depressions in each vertical group. Tubercle brown, tiny, very depressed. Seed with a thin, non-adherent wall.

Culm: unbranched, 5 cm - 1 m long, to 0.5 mm wide, circular in cross-section or bluntly three- to five-angled, rarely deeply grooved, spongy, enclosed basally by two fused sheaths.

Spikelets: solitary, 3 - 6 mm long, 1.5 - 2 mm wide, egg-shaped with a blunt to pointed apex, with 20 to 60 floral scales. Scales spirally arranged and overlapping, brown to dark brown with a paler midrib, 1.5 - 2.5 mm long, 1 mm wide, egg-shaped with a rounded to pointed apex.

Similar species: No information at this time.

Flowering: May to early June

Habitat and ecology: Wet areas. Has been found in prairies, fens, and sandy areas of the Chicago Region. Occasionally submersed in water.

Occurence in the Chicago region: native

Etymology: Eleocharis comes from the Greek words heleios, meaning "dwelling in a marsh," and charis, meaning grace. Tenuis means thin, or slender. Verrucosa means "like a wart."

Author: The Morton Arboretum

For the most part, our specimens are from wet, hard, clay soil of the borders of ponds and wet woods. Our Jasper County specimen is from a wet, interdunal flat.