Setaria viridis
Plants annual. Culms 20-250 cm; nodes glabrous. Sheaths glabrous, sometimes scabridu-lous, margins ciliate distally; ligules 1-2 mm, ciliate; blades to 20 cm long, 4-25 mm wide, flat, scabrous or smooth, glabrous. Panicles 3-20 cm, densely spicate, nodding only from near the apices; rachises hispid and villous; bristles 1-3, 5-10 mm, antrorsely scabrous, usually green, rarely purple. Spikelets 1.8-2.2 mm. Lower glumes about as long as the spikelets, triangular-ovate, 3-veined; upper glumes nearly equaling the upper lemmas, elliptical, 5-6-veined; lower lemmas slightly exceeding the upper lemmas, 5-veined; lower paleas about as long as the lower lemmas, hyaline; upper lemmas very finely and transversely rugose, pale green, 5-6-veined; upper paleas similar to the upper lemmas. 2n = 18.
Distribution
N.C., Conn., N.J., N.Y., Wash., Del., D.C., Wis., W.Va., Mass., Maine, N.H., R.I., Vt., Fla., Wyo., N.Mex., Tex., La., Md., Tenn., S.C., Pa., Calif., Nev., Va., Colo., Ala., Ark., Ariz., Ga., Iowa, Idaho, Ind., N.Dak., Nebr., Ohio, Okla., Oreg., S.Dak., Utah, Alaska, Kans., Ill., Mont., Mo., Minn., Mich., Alta., B.C., Man., N.B., Nfld. and Labr. (Labr.), N.S., N.W.T., Ont., P.E.I., Que., Sask., Yukon, Miss., Ky.
Discussion
Setaria viridis resembles S. italica but differs in its shorter spikelets and rugose upper florets, and mode of disarticulation. It is also a more aggressive weed. It is native to Eurasia but is now widespread in warm temperate regions of the world.
Selected References
None.
Key
| 1 | Culms 100-250 cm tall; blades 10-25 mm wide; panicles 10-20 cm long | Setaria viridis var. major |
| 1 | Culms 20-100 cm tall; blades 4-12 mm wide; panicles 3-8 cm long | Setaria viridis var. viridis |