Plants annual, or short-lived perennials; cespitose, not rhizomatous. Culms (10)25-150 cm, erect or decumbent, branching, sometimes rooting at the lower nodes; nodes 3-6. Sheaths keeled, basal sheaths usually with papillose-based hairs, rarely glabrous; ligules 0.3-1.5 mm; blades 2-18 cm long, 1-6 mm wide, flat or involute, glabrous, scabrous, or pilose. Panicles with 2-7 spikelike primary branches, these digitate or the rachises to 1 cm; longest primary branches 20-25 cm, axes triquetrous, not winged, with spikelets in unequally pedicellate groups of 3(-5) on the basal ½ (J. Wipff, pers. comm.). Spikelets 1.3-2.8 mm. Lower glumes absent or to 0.1 mm; upper glumes 1-2 mm long, from 3/4 to almost as long as the spikelets, almost glabrous or sparsely to densely pubescent with clavate to capitate hairs (use 20x magnification), glume apices rounded; lower lemmas equaling the spikelets, glabrous or glandular-pubescent, 5-7-veined, veins unequally spaced, outer 3 veins on each side closer to each other than the midvein is to the inner lateral veins; upper lemmas 1.3-2 mm, apiculate, dark brown at maturity; anthers 0.3-0.6 mm. 2n = 36, 54.
Conn., N.J., N.Y., Del., D.C., W.Va., Fla., N.H., Tex., La., Tenn., N.C., S.C., Pa., Va., Ala., Mass., R.I., Ark., Vt., Ill., Ga., Ind., Iowa, Md., Kans., Okla., Ohio, Mo., Mich., Miss., Ky.
Digitaria filiformis grows throughout the warmer parts of the eastern United States, van filifomis the most widespread of its varieties, extending into Mexico.
|1||Lower lemmas glabrous||Digitaria filiformis var. laeviglumis|
|1||Lower lemmas pubescent.||> 2|
|2||Basal leaf sheaths glabrous; cauline blades about 1 mm wide, folded or involute||Digitaria filiformis var. dolichophylla|
|2||Basal leaf sheaths with papillose-based hairs; cauline blades 1-6 mm wide, flat.||> 3|
|3||Spikelets 1.3-1.9 mm long; panicle branches 3-13 cm long; culms 10-80 cm tall||Digitaria filiformis var. filiformis|
|3||Spikelets 2-2.8 mm long; panicle branches 10-25 cm long; plants 75-150 cm tall||Digitaria filiformis var. villosa|