Plants annual. Culms 80-160 cm, erect or spreading,
sometimes rooting at the lowest nodes, often developing short axillary flowering
shoots at most upper nodes when mature; lower nodes glabrous or puberulent;
upper nodes glabrous. Sheaths glabrous; ligules absent;
blades 1-27 cm long, 0.8-30 mm wide. Panicles of primary culms
7-35 cm, rachises and branches glabrous or hispid, hairs to 3 mm, papillose-based;
primary branches 2-8 cm, usually spreading and rather distant, often
with secondary branches. Spikelets 2.5-5 mm, disarticulating at maturity,
usually purple or streaked with purple, usually hispid, hairs papillose-based.
Upper glumes about as long as the spikelets; lower florets sterile;
lower lemmas unawned or awned, awns to 16 mm; lower paleas well-developed;
upper lemmas broadly obovoid or orbicular, narrowing to an acute or acuminate
coriaceous portion that extends into the membranous tip, boundary between the
coriaceous and membranous portions not marked by minute hairs; anthers
0.4-1.1 mm. Caryopses 1.2-2.5 mm, broadly obovoid or spheroid, yellowish;
embryos 1.4-2 mm, 80-91% as long as the caryopses. 2n = 36.
Echinochloa muricata is native to North America, growing from
southern Canada to northern Mexico in moist, often disturbed sites (but
not rice fields). It resembles E. crus-galli in
gross morphology and ecology, but differs consistently by the characters
used in the key. The two varieties tend to be distinct, but there is
some overlap in both morphology and geography.
Spikelets 2.5-3.8 mm. Lower glumes 0.9-1.6 mm;
upper glumes 2.8-3.8 mm; lower lemmas unawned or awned, awns to
10 mm; anthers 0.4-0.7 mm.
Echinochloa muricata var. microstachya is the common variety in
the western part of North America, extending east to the Missouri River and
the Texas panhandle.
Erect or decumbent, branched from the base, often 1 m or more; sheaths glabrous; blades 8-30 mm wide; infl 1-3 dm, erect, typically with spreading, somewhat distant branches 2-8 cm, the longer ones rebranched, the main axis and branches glabrous or variously hairy but without conspicuous long setae, the hairs rarely over 3 mm; spikelets commonly purplish; second glume and sterile lemma about equal, usually beset with stout, papillose- based hairs at least on the veins, the glume awnless or nearly so; fertile lemma ca twice as long as wide, abruptly narrowed to an acuminate, persistent tip not sharply differentiated from the body; 2n=36. Damp or muddy ground, or a weed in waste places; Me. and Que. to Alta. and Wash., s. to Fla., Tex., Calif., and n. Mex. Two vars., both widespread in our range.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.