Plants annual. Culms (30)50-200+ cm tall, to 2.5
cm thick; nodes pilose or villous, upper nodes usually with sparser and
shorter pubescence, occasionally glabrous. Lower sheaths usually hispid,
hairs papillose-based, sometimes just papillose; upper sheaths hispid
or glabrous; ligules absent; blades to 55 cm long, 10-35(60) mm
wide, scabrous. Panicles 8.5-35 cm, erect to slightly drooping, nodes
hispid, hairs 3.5-5 mm, papillose-based, sometimes sparsely so, internodes usually
glabrous, sometimes hispid, hairs papillose-based; primary branches 1-10
cm, loosely erect, not concealed by the spikelets, nodes usually hispid, hairs
papillose-based, sometimes glabrous, internodes scabrous, sometimes also sparsely
hispid, hairs papillose-based; secondary branches present on the longer
primary branches. Spikelets 3-5 mm, disarticulating at maturity, scabrous
to variously muricate and hairy, hairs usually not papillose-based, margins
sometimes with a few papillose-based hairs. Lower glumes usually more
than 1/2 as long as the spikelets, abruptly narrowing to a fine, 0.5 mm point;
lower florets sterile; lower lemmas usually awned, awns 8-25(60)
mm; lower paleas subequal to the lower lemmas; upper lemmas 3-5
mm long, about 1.5 mm wide, not or scarcely exceeding the upper glumes, narrowly
ovate to elliptical, coriaceous portion subacute, tips acuminate, membranous,
without a line of hairs at the base of the tip; anthers 0.6-1(1.2) mm.
Caryopses 1.2-1.8 mm, brownish; embryos 52-77% as long as the
caryopses. 2n = 36.
Echinochloa walteri grows in wet places, often in shallow water and brackish
marshes. It is a native species, found in both disturbed and undisturbed sites
although not in rice fields. Occasional specimens of E. walteri with
glabrous lower sheaths and short awns can be distinguished from E.
crus-pavonis by their less dense panicles.
Tall and usually erect, mostly 1-2 m; lower sheaths beset with coarse, papillose-based hairs, rarely glabrous; blades up to 25 mm wide; infl dense, often nodding, 1-3.5 dm, the spikelets almost concealed in a mass of awns 1-3 cm on the sterile lemmas; second glume with an awn 2-10 mm; fertile lemma elliptic, nearly or fully 3 times as long as wide, with a minute, withering tip, but this not set off by a line of hairs as in no. 4 [Echinochloa crusgalli (L.) P. Beauv.]; 2n=36. Marshes and wet soil, especially along the coast; Mass. to Fla. and Tex., and irregularly inland to Mich., Wis., Io. and Mo.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.