Plants annual. Culms 70-150 cm, erect, glabrous. Sheaths
glabrous; ligules absent; blades 8-35 cm long, 3-20(30) mm
wide, glabrous. Panicles 7-18 cm, erect to slightly drooping at
maturity, rachises not or only sparsely hispid, nodes with papillose-based
hairs; branches
numerous, appressed or ascending, spikelike, not or only sparsely hispid,
hairs papillose-based; primary branches 1.5-4 cm, glabrous or sparsely
hispid, hairs to 3 mm, papillose-based; secondary branches, if
present, usually concealed by the densely packed spikelets; longer
pedicels 0.2-0.5 mm.
Spikelets 3-3.5 mm, often with 1 sterile and 2 bisexual florets,
not disarticulating at maturity (particularly those near the bases of
the panicles), scabrous or short-hispid but without papillose-based hairs,
green and pale at maturity, apices usually obtuse, varying to acute. Upper
glumes narrower and shorter than the upper
lemmas; lower florets sterile; lower lemmas unawned; lower
paleas
subequal to the lower lemmas; upper lemmas 2.5-3 mm, ovate to elliptic,
coriaceous portion terminating abruptly at the base of the membranous
tip; anthers
0.8-1 mm. Caryopses 1.7-2.2 mm long, 1.6-1.8 mm wide, whitish; embryos
66-86% as long as the caryopses. 2n = 36 [J.D.
Munshi, J.K. Pal, V. Bansikar, and N. Pandit. 1994. Eco-cytological studies
of Echinochloa frumentacea (Roxb.) Link of Diara Lands of Bhagalpur,
Bihar. Proc. Indian Sci, Congr. 81:112],
54.
Echinochloa frumentacea originated in India, and possibly also in Africa.
It is grown for grain, fodder, and beer, although not as extensively as in the
past. It is found occasionally in the contiguous United States and southern Canada,
the primary source being birdseed mixes. It used to be confused with E.
esculenta, from which it differs in its whitish caryopses and proportionately
smaller embryos. Hybrids between E. frumentacea and E.
colona are partially fertile; those with E. esculenta are sterile.