Plants annual. Culms (7)45-110 cm, often geniculate below, usually
ascending to erect above, rarely branching at the base, often branching distally;
internodes hollow. Sheaths glabrous, margins occasionally sparsely
ciliate on the basal 1/2; ligules 2.2-3.8 mm, membranous, truncate, somewhat
erose; blades 4-20 cm long, 4-8 mm wide, both surfaces smooth or scabridulous.
Panicles 20-35 cm, with 20-30(90) racemose branches; branches
2.5-7 cm, ascending, mostly stiff. Spikelets 4-5 mm, usually somewhat
imbricate, with 4-6(7) florets. Lower glumes 0.9-1.9 mm, usually lanceolate,
sometimes falcate, acute; upper glumes 1.8-2.3 mm, ovate, acute to obtuse;
lemmas 2.4-3 mm, narrowly elliptic to ovate, membranous, midveins and
lateral veins sericeous basally, lateral veins prominent, excurrent, apices
acute to broadly acute, unawned, sometimes mucronate; paleas glabrous;
anthers 3, 0.6-0.8 mm. Caryopses 1.1-1.4 mm long, 0.7 mm wide,
elliptic, depressed obovate in cross section. 2n = 20.
Leptochloa panicoides is native from the central Mississippi and Ohio
river drainages south through Mesoamerica to Brazil. It usually grows in somewhat
mesic habitats. It has been reported from two counties in Texas, but no specimens
documenting the reports have been found so they are not shown.
Nicora (1995) merged Leptochloa panicoides with L.
scabra, but the two differ consistently in the number of panicle branches,
spikelet length, and prominence of the lemma veins.
From Flora of Indiana (1940) by Charles C. Deam
In 1916 I found a few specimens of this species in a large, miry, muddy flat in what is locally known as Pitcher's Lake, about 5 miles west of Mt. Vernon, Posey County. Pitcher's Lake is in reality a shallow lagoon about 2 miles long and a half mile wide. It is filled with water during the winter months and is usually nearly or entirely dry in autumn. This grass was found with Lindernia, Cyperus, Acnida, and Leersia oryzoides. I revisited the place in 1920 and found a few more specimens. The Indiana specimens are the only ones known north of Mississippi. The species is rare, having been found only in Indiana, Mississippi, Louisiana, and Texas, and southward to Brazil.
Another chiefly tropical sp., is reported to extend n. to s. Ind. and s. Ill. It differs in its wider, nearly smooth lvs, the main ones 5-10 mm wide, and in its 5-7-fld spikelets 3.5-5 mm. (Diplachne p.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.