Herbs, perennial, cespitose, 3--9 dm. Roots often with terminal tubers. Culms erect, terete, 1--3 mm diam., smooth. Cataphylls 1, maroon to brown, apex acute. Leaves: basal 1--3, cauline 1--2; auricles 0.5--2 mm, apex rounded, scarious; blade green or maroon, compressed, 2--16 cm x 1--2 mm. , with faint ringlike bands at position of septa. Inflorescences terminal panicles of 40--100(--200) heads, 4--16 cm, branches ascending to spreading; primary bract erect to ascending; heads 2--10-flowered, hemispheric to obpyramidal, 0.3--0.5 mm diam. Flowers: tepals straw-colored, lanceolate, apex acuminate; outer tepals (2.2--)2.6--2.9 mm; inner tepals (1.8--)2.4--2.8; stamens 3, anthers 2/3 to equal filament length. Capsules exserted, chestnut brown, 1-locular, narrowly obpyriform to narrowly ovoid, 2.4--2.9 mm, apex acute, valves separating at dehiscence. Seeds ellipsoid, 0.3--0.5 mm, not tailed; body clearly yellow-brown. . 2n = 40. Fruiting summer. Wet sands, peaty sands, or peat, exposed shores of ponds and lakes, depressions in savannas and flatwoods, moist to wet, much disturbed clearings, roadsides and ditches; 0--700 m; Ala., Ark., Del., Fla., Ga., La., Miss., N.J., N.C., S.C., Tenn., Tex., Va. Juncus elliottii has tubers at the ends of the roots.
Stems slender, cespitose, erect, 2-7 dm; some of the roots with subterminal tuberous thickenings; lvs terete, septate, 1-3 mm thick; infl narrowly pyramidal or ovoid, 1-12 cm, less than half as thick, congested to loosely branched, with 3-100 hemispheric or obpyramidal, 2-7-fld heads 3-5 mm thick; fls eprophyllate; tep subequal, lanceolate, 2.2-3 mm, aristulate, very narrowly scarious-margined; stamens 3; fr unilocular, dark purple-brown, prismatically oblong-trigonous, about equaling the tep, very abruptly short-acuminate or merely apiculate. Damp or wet, sandy or peaty soil, especially in pine-barrens; s. Del. to Fla. and Tex., chiefly on the coastal plain. Spring.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.