Echinochloa colona
Echinochloa oplismenoides
awnless barnyard grass, jungle rice, jungle ricegrass, or jungle-rice, small barnyard grass, watergrass
Chihuahuan barnyard grass, Chihuahuan cockspur
10-70 cm;
lower nodes glabrous or hispid, hairs appressed;
upper nodes glabrous.
to 100 cm, erect, succulent, glabrous, branching from the lower nodes.
glabrous;
ligules absent, ligule region frequently brown-purple;
blades 8-22 cm long, 3-6(10) mm wide, mostly glabrous, sometimes hispid, hairs papillose-based on or near the margins.
glabrous or hispid with papillose-based hairs;
ligules absent or the ligule region pubescent;
blades 10-35 cm long, 5-10 mm wide.
2-12 cm, erect, rachises glabrous or sparsely hispid;
primary branches 5-10, 0.7-2(4) cm, erect to ascending, spikelike, somewhat distant, without secondary branches, axes glabrous or sparsely hispid, hairs 1.5-2.5 mm, papillose-based.
15-30 cm, narrow;
primary branches appressed to ascending, with papillose-based hairs at the base of the spikelets.
2-3 mm, disarticulating at maturity, pubescent to hispid, hairs usually not papillose-based, tips acute to cuspidate.
4-5 mm, disarticulating at maturity.
with hairs over the veins, glabrous, scabrous, or hispid between the veins;
upper glumes about equal to the spikelets, muticous or awned, awns to 1 mm;
lower florets sterile;
lower lemmas unawned or awned, awns 8-16(50) mm;
lower paleas absent or hyaline and subequal to the lemmas;
upper lemmas 4-4.5 mm long, 1.7-1.9 mm wide, elliptic;
anthers 0.5-0.7 mm, purple.
about 1/2 as long as the spikelets;
upper glumes about as long as the spikelets;
lower florets usually sterile, occasionally staminate;
lower lemmas unawned, similar to the upper glumes;
lower paleas subequal to the lemmas;
upper lemmas 2.6-2.9 mm, not or scarcely exceeding the upper glumes, elliptic, coriaceous portion rounded distally, passing abruptly into a sharply differentiated, membranous, soon-withering tip;
anthers 0.7-0.8 mm.
1.2-1.6 mm, whitish;
embryos 63-83% as long as the caryopses.
2.7-2.9 mm long, 1.7-1.8 mm wide, elliptic in outline, mucronate;
embryos about 75% as long as the caryopses;
hila obovate.
= 54.
= unknown.
Echinochloa colona
Echinochloa oplismenoides
Echinochloa colona is widespread in tropical and subtropical regions. It is adventive and weedy in North America, growing in low-lying, damp to wet, disturbed areas, including rice fields. The unbranched, rather widely-spaced panicle branches make this one of the easier species of Echinochloa to recognize.
Hitchcock (1913) considered that 'colonum' was a non-declining contraction, but dictionaries of Linnaeus' time treated it as a declining adjective. Because Linnaeus was the first to name the species (as "Panicum colonum"), it seems best to follow the practice considered correct in his day; hence "E. colona".
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Echinochloa oplismenoides was first found in the United States, in southern Arizona, in 1993 (Fishbein 1995). It was previously known only from Mexico, with a range that extends from northwestern Mexico to Guatemala. The southern Arizonan plants were found near a cattle tank in wet grasslands. Fishbein stated that it was impossible to tell whether they represented a previously overlooked native species or an introduction.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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