Eleocharis tenuis var. verrucosa
Rhodora 41: 66. 1939.
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.
Phenology: Fruiting summer.
Habitat: Fresh, often calcareous, shores, wet woods, ditches
Elevation: 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).