Plants perennial; usually cespitose, often with short, knotty rhizomes, occasionally with elongate rhizomes, never stoloniferous. Culms 5-180 cm, erect, mostly glabrous, lower nodes sometimes with hairs. Sheaths shorter than the internodes, open; ligules membranous and ciliate or of hairs; blades 6-25 cm long, 1-8 mm wide, flat or involute, margins not thick and cartilaginous. Inflorescences terminal, usually panicles (sometimes reduced to racemes), 5-40 cm, exceeding the upper leaves, exserted. Spikelets 4-10(13) mm, laterally compressed, with 4-11(16) florets, more than 1 floret bisexual; sterile florets distal to the fertile spikelets; disarticulation above the glumes. Glumes from shorter than to equaling the distal florets; lower glumes 1(3)-veined; upper glumes shorter than or about equal to the lower glumes, 1-3(9)-veined, unawned; calluses usually glabrous, sometimes pilose; lemmas hyaline or membranous, 3-veined, veins usually shortly hairy below, apices rounded to truncate, emarginate to bilobed, midvein often excurrent to 0.5 mm, lateral veins not or more shortly excurrent; paleas glabrous or shortly pubescent on the lower back and margins, veins glabrous or ciliolate; lodicules 2, free or adnate to the palea; anthers 3, reddish-purple. Caryopses dorsiventrally compressed and reniform in cross section, dark brown; embryos about 2/5 as long as the caryopses. x = 10. Name from the Latin tres, three, and dens, tooth, referring to the three shortly excurrent veins of Tridens flavus, the type species.
Spikelets 3-9-fld, disarticulating above the glumes and between the lemmas; first glume 1- or 3-veined, the second 1-5-veined; lemmas broad, rounded on the back, obtuse or retuse, densely hairy at base and on the 3 veins, at least in the lower half, the midrib usually shortly excurrent, and the 2 lateral veins produced as minute teeth; palea broad, its 2 veins near the margin, smooth or short-hairy; stigmas dark purple; grain strongly concave on the ventral side; perennial grasses with flat lvs and ample panicles and without long rhizomes. (Triodia, in part) 15, New World.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.