TaxonIllustrator 
FNA24 P13 Leersia pg 43.jpegLeersia monandra
Leersia lenticularis
Leersia virginica
Linda Ann Vorobik
Linda Ann Vorobik
Linda Ann Vorobik
FNA24 P14 Leersia pg 45.jpegLeersia hexandra
Leersia oryzoides
Linda Ann Vorobik
Linda Ann Vorobik

Plants usually perennial, rarely annual; terrestrial or aquatic; rhizomatous or cespitose; synoecious. Culms 20-150 cm (occasionally longer in floating mats), erect or decumbent, often rooting at the nodes, branched or unbranched. Leaves equitably distributed along the culm; sheaths open; auricles absent; ligules membranous; pseudopetioles absent; blades aerial, linear to broadly lanceolate, flat or folded, sometimes involute when dry. Inflorescences terminal panicles, usually exserted, axillary panicles sometimes also present; disarticulation beneath the spikelets. Spikelets bisexual, with 1 floret; florets laterally compressed, linear to suborbicular in sideview. Glumes absent; calluses not stipelike, glabrous; lemmas and paleas subequal, chartaceous to coriaceous, ciliate-hispid or glabrous, tightly clasping along the margins; lemmas 5-veined, obtuse or acute to acuminate, sometimes mucronate, usually unawned; paleas 3-veined, unawned; lodicules 2; anthers 1, 2, 3, or 6; styles 2, bases fused, stigmas laterally exserted, plumose. Caryopses laterally compressed; embryos about 1/3 as long as the caryopses; hila linear, x = 12.

Distribution

Conn., N.J., N.Y., Wash., Va., Del., D.C, Wis., W.Va., Md., Fla., Wyo., N.H., N.Mex., Tex., La., Tenn., N.C., S.C., Pa., Nev., Mass., Maine, R.I., Vt., Puerto Rico, Colo., Calif., Ala., Kans., N.Dak., Nebr., Okla., S.Dak., Miss., Ark., Ill., Ga., Ind., Iowa, Ariz., Idaho, Ohio, Utah, Mo., Minn., Mich., Mont., Ky., Oreg., B.C., Man., N.B., N.S., Ont., P.E.I., Que., Sask.

Discussion

Leersia is a genus of about 17 aquatic to mesophytic species, growing primarily in tropical and warm-temperate regions. Five species are native to the Flora region. Leersia is closely allied to Oryza. It is unusual in the variability in stamen numbers among its species.

Key

1 Spikelets 1.5-2 mm long, glabrous; plants not rhizomatous Leersia monandra
1 Spikelets 2.5-6.5 mm long, usually ciliate on the margins and keel, and glabrous or pubescent elsewhere; plants rhizomatous. > 2
2 Spikelets nearly as wide as long Leersia lenticularis
2 Spikelets not more than 1/2 as wide as long. > 3
3 Anthers 2; spikelets 2.5-3.6 mm long; panicle branches single at all nodes Leersia virginica
3 Anthers 3 or 6; spikelets 3.2-6.5 mm long; panicle branches 1-2 or more at the lower nodes, single at the upper nodes. > 4
4 Panicles exserted, 5-15 cm long; branches appressed to ascending, spikelet-bearing to near the base; anthers 6; spikelets 3.2-4.7(5) mm long Leersia hexandra
4 Panicles exserted or enclosed, 10-30 cm long; branches spreading on exserted panicles, naked on the lower 1/3; anthers 3; spikelets (4)4.2-6.5 mm long Leersia oryzoides

"decumbent" is not a number.

... more about "Leersia"
6 +, 3 +, 2 +  and 1 +
Grant L. Pyrah +
1 (?) +  and 3 (?) +
keeled +  and rounded +
pseudopetiolate +  and branching +
divergent +  and parallel +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not evident +
linear +  and broadly lanceolate flat or folded +
spikelike +
not stipelike +
unbranched +, branched +  and rooting +
20 cm200 mm <br />0.2 m <br /> (500 cm5,000 mm <br />5 m <br />) +
decumbent +  and erect +
20 cm200 mm <br />0.2 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
Conn. +, N.J. +, N.Y. +, Wash. +, Va. +, Del. +, D.C +, Wis. +, W.Va. +, Md. +, Fla. +, Wyo. +, N.H. +, N.Mex. +, Tex. +, La. +, Tenn. +, N.C. +, S.C. +, Pa. +, Nev. +, Mass. +, Maine +, R.I. +, Vt. +, Puerto Rico +, Colo. +, Calif. +, Ala. +, Kans. +, N.Dak. +, Nebr. +, Okla. +, S.Dak. +, Miss. +, Ark. +, Ill. +, Ga. +, Ind. +, Iowa +, Ariz. +, Idaho +, Ohio +, Utah +, Mo. +, Minn. +, Mich. +, Mont. +, Ky. +, Oreg. +, B.C. +, Man. +, N.B. +, N.S. +, Ont. +, P.E.I. +, Que. +  and Sask. +
capillary +
sometimes longer +
sterile +, fertile +, sexual +, unisexual +  and bisexual +
linear +  and suborbicular +
cylindrical +, oblong +  and ovoid +
subtending +
reduced +
uncinate +
solid +  and hollow +
aerenchymatous +
distributed +
glabrous +  and ciliate-hispid +
mucronate +, acute +  and acuminate +
subequal +
chartaceous +  and coriaceous +
membranous +
annular +
inconspicuous +
fleshy +  and membranous +
complex +  and simple +
concealed +  and prominent +
2 +  and 1 +
well-developed +
glabrous +  and ciliate-hispid +
1-keeled +
subequal +
chartaceous +  and coriaceous +
dry +  and fleshy +
not prolonged +
pyrah1969a +
[9/10] +, /2 +  and 1 +
terete +  and compressed +
1 +  and 3 +
simple +  and compound +
2 (?) +  and 3 (?) +
triangular +  and dome--shaped +
Gramineae +
Leersia +
Poaceae tribe Oryzeae +
membranous +
annual +  and perennial +
plant +  and cespitose +
aquatic +  and terrestrial +