Plants with creeping rhizomes 0.5-1 mm thick. Culms 3-42 cm × 0.3-0.6 mm. Leaves: distal leaf sheaths often disintegrating, thinly membranous-translucent, inflated distally, often wrinkled, apex blunt. Spikelets ellipsoid, 1.5-9 × 1-3.5 mm, apex acute to acuminate; proximal scale without flower, not amplexicaulous; floral scales to 65, 5-7 per mm of rachilla, loosely appressed to appressed, elliptic, 1-3 × 0.4-1.6 mm, membranous, apex acute. Flowers: perianth bristles (0-)5-8, typically 7, white to stramineous, spinules dense to few; styles 2-fid, rarely 3-fid. Achenes stramineous to green or dark brown, biconvex, rarely trigonous, obovoid to obpryiform, 0.4-1.1 × 0.3-0.8 mm, very finely reticulate at 40X. Tubercles whitish to stramineous or green, 0.2-0.7 × 0.2-0.4 mm, apex acute to acuminate. The varieties of Eleocharis flavescens are difficult to delimit, especially in the south, and identifications of some specimens to variety are problematic.