Mexican Sprangletop

Leptochloa uninervia (Presl) Hitchc. & Chase, Contr. U. S Nat. Herb. 18: 383. 1917.
Megastachya uninervia Presl, Rel. Haenk. 1: 283. 1830.
Poa uninervia Kunth. R6v. Gram. Suppl. XXVIII. 1830. (Based on Megastachya uninervia Presl.) Eragrostis uninervia Steud. Syn. Gram. 278. 1854. (Based on Megastachya uninervia Presl.) Atropis carinata Griscb. Abh. Ges. Wiss. Gott. 24: 291. 1879. (Type from Argentina.) Leptochloa imbricala Thurber, in S. Wats. Bot. Calif. 2: 293. 1880. (Type from San Diego County,
California, Palmer 404.) Diplachne imbricala Scribn. Bull. Torrey Club 10: 30. 1883. (Based on Leptochloa imbricala Thurb.) Brizopyrum uninervium Fourn. Mex. PI. Gram. 2: 121. 1886. (Based on Megastachya uninervia
Presl.) Leptochloa Virletii Foum. Mex. PI. Gram. 2: 147. 1886. (Type from San Luis Potosf, Mexico,
Virlel 1404.) Diplachne tarapacana Philippi, Anal. Mus. Nac. Chile 8: 88. 1891. (Type from Tarapac4, Chile.) Rabdochloa imbricala Kuntze, Rev. Gen. 788. 1891. (Based on Leptochloa imbricala Thurb.) Diplachne carinata Hack. Bol. Acad. Ci. C6rdoba 16: 253. 1900. (Based on Atropis carinata
Griseb.) Diplachne uninervia L. Parodi, Univ. Nac. Buenos Aires Rev. C^ntr. Estud. 18: 147. 1925. (Based
on Megastachya uninervia Presl.)
Annual; culms erect, simple or sparingly branched, 30-100 cm. tall, glabrous; sheaths rounded on the back, glabrous or scabrous, shorter than the intcrnodcs; ligule membranaceous, 2-3 mm. long; blades firm, flat or loosely involute, attenuate scabrous, 10-45 cm. long, 1-4 mm. wide; panicle 10-30 cm. long; spikes numerous, approximate, stiffly ascending, the lower ones 4-9 cm. long, the upper ones gradually shorter and closer together; spikelets lead-colored, 6-9-flowered, 5-7 mm. long, appressed; first glume narrow, acute, 1-1.5 mm. long, the second much broader, abruptly acute or obtuse, mucronate; lemmas 2-3 mm. long, scarcely narrowed toward the tip, abruptly subacute or obtuse, minutely lobed, apiculate, the lateral nerves more or less excurrent, the margins pilose near the base.
Type locality: Mexico (Haenke).
Distribution; Swamps, wet ground, and wet roadside ditches, Mississippi to Colorado and California, and southward to British Honduras; introduced from Maine to New Jersey; West Indies; also from Peru and Brazil to Argentina.

Annuals, Perennials, Terrestrial, not aquatic, Stems trailing, spreading or prostrate, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems mat or turf forming, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems compressed, flattened, or sulcate, Stems branching above base or distally at nodes, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems with inflorescence 1-2 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath hairy at summit, throat, or collar, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Leaf blades scabrous, roughened, or wrinkled, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence a panicle with narrowly racemose or spicate branches, Inflorescence branches more than 10 to numerous, Inflorescence branches 1-sided, Flowers bisexual, Spikelets sessile or subsessile, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 2 florets, Spikelets with 8-40 florets, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the florets, Spikelets secund, in rows on one side of rachis, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequal, Glumes shorter than adjacent lemma, Glumes keeled or winged, Glumes 1 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 3 nerved, Lemma body or surface hairy, Lemma apex truncate, rounded, or obtuse, Lemma awnless, Lemma mucronate, very shortly beaked or awned, less than 1-2 mm, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.