Plants with firm, knotty, shortly rhizomatous bases. Culms 60-180
cm. Sheaths keeled, mostly glabrous, collars pubescent; ligules
to 0.5 mm, membranous, ciliate; blades 3-10 mm wide, glabrous or sparsely
hispid, apices attenuate and involute. Panicles 15-40 cm long, 3-5 cm
wide, erect or nodding; branches 10-15(25) cm, strongly divergent to
drooping, stiff or lax, lower branches naked for 1/3-1/2 of their length; pedicels
3-8 mm. Spikelets 5-10 mm long, with 4-8 florets. Lower glumes
2.5-3 mm, often mucronate; upper glumes 3.5-4 mm; lemmas 3-5 mm,
lateral veins puberulent or ciliate to well above midlength, midveins and lateral
veins usually excurrent, midveins extending to 0.5 mm, lateral vein extensions
shorter; paleas as long as the lemmas, widened below; anthers
1-1.5 mm. Caryopses 1.8-2 mm. 2n = 40.
Tufted and sometimes with very short rhizomes, 8-15 dm; sheaths bearded at the top, otherwise glabrous, as are the blades, these 3-8 mm wide, elongate to a slender tip; infl viscid, with loosely spreading-ascending branches villous at base above; spikelets purple (yellow), narrowly ovoid, scarcely compressed, 5-10 mm, 4-9-fld, the lateral ones appressed along the branchlets or on looser pedicels to ca 3 mm; glumes unequal, firm, oblong or ovate, 2.5-3.5 mm, 1- veined, obtuse or often mucronate; lemmas regularly imbricate, densely villous on the basal half; 2n=40. Fields, roadsides, and open woods; Mass. to s. Ont., s. Mich., and Nebr., s. to Fla. and Tex. (Triodia f.) Most of our plants belong to the widespread var. flavus, as principally described above. The more strictly southeastern var. chapmanii (Small) Shinners reaches our range in se. Va. and s. N.J. It has more divergent panicle-branches, villous all around at the more strongly buttressed base, and the spikelets are on longer, more divergent pedicels mostly 3-20 mm. (T. c.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.