Difference between revisions of "Digitaria ischaemum"

Revision as of 16:13, 30 October 2019

Illustrator: Linda A. Vorobik, Hana Pazdírková

Plants annual or of indefinite duration. Culms 20-55(70) cm, decumbent, branching and rooting at the lower nodes; nodes 3-4. Sheaths glabrous or sparsely pubescent; ligules 0.6-2.5 mm; blades 1.5-9 cm long, 3-5 mm wide, glabrous, with a few papillose-based hairs basally. Panicles terminal and axillary; terminal panicles with 2-7 spikelike primary branches, subdigitate or on 0.5-2 cm rachises; primary branches 6-15.5 cm, axes wing-margined, wings at least 1/2 as wide as the midribs, bearing spikelets in groups of 3, lower portions of the longer pedicels adnate to the axes; secondary branches rarely present; axillary inflorescences always present in some of the lower sheaths, entirely or partially concealed. Spikelets 1.7-2.3 mm, homomorphic, narrowly elliptic. Lower glumes absent or a veinless, membranous rim; upper glumes 1.3-2.3 mm, from 3/4 as long as to equaling the upper lemmas, appressed-pubescent; lower lemmas 1.7-2.3 mm, 7-veined, veins unequally spaced, smooth, pubescent; upper lemmas dark brown at maturity; anthers 0.4-0.6 mm. 2n = 36.

Idaho, Mont., Wash., Conn., N.J., N.Y., Va., Del., D.C, Wis., W.Va., Md., Alta., B.C., Man., N.B., N.S., Ont., P.E.I., Que., Sask., Fla., Wyo., N.H., N.Mex., Tex., La., Tenn., N.C., S.C., Pa., Nev., Mass., Maine, R.I., Vt., Puerto Rico, Colo., Virgin Islands, Calif., Ala., Kans., N.Dak., Nebr., Okla., S.Dak., Ark., Ill., Ga., Ind., Iowa, Ariz., Ohio, Utah, Mo., Minn., Mich., Miss., Ky., Oreg.

Discussion

Digitaria ischaemum is a Eurasian weed that is now common in lawns, gardens, fields, and waste ground in warm-temperate regions throughout the world, including much of the Flora region. Larger plants with 5-7 inflorescence branches 8-15 cm long have been called var. mississippiensis (Gatt.) Fernald, but they intergrade with more typical plants, and so do not merit taxonomic recognition.

Selected References

None.

Lower Taxa