Plants cespitose, with knotty, shortly rhizomatous bases. Culms 60-125 cm. Sheaths rounded or the basal sheaths keeled, glabrous, except for a few hairs on either side of the collar; ligules 1-2 mm, membranous, ciliate; blades 2-5 mm wide, elongate, usually involute distally. Panicles 8-16(20) cm long, 1.5-4 cm wide, not dense; branches to 8(10) cm, erect to divergent, stiff; pedicels shorter than 1 mm. Spikelets 4-6 mm long, pale to dark purple, with 4-6 florets. Glumes 1-veined; lower glumes 4-4.5 mm; upper glumes about 5 mm; lemmas 3-4 mm, veins pubescent to midlength or beyond, midveins excurrent, lateral veins often excurrent; paleas 3-3.5 mm, veins ciliolate, bases bowed-out; anthers 1-1.5 mm. Caryopses 1.5-1.8 mm. 2n = 40.
Ga., Tex., La., N.C., Ala., Miss., S.C., Fla.
Tridens ambiguus grows on the southeastern coastal plain, from North Carolina to Texas. It is usually found in mesic to perennially moist soils of pine flatwoods and pine-oak savannahs, in seasonally inundated depres¬sions, and at the margins of pitcher plant bogs, often in disturbed sites.