Lax Gaping Grass

Panicum laxum Sw. Prodr. 23. 1788
Panicum agrostidiforme Lam. Tab. Encyc. 1: 172. 1791.
Panicum tenuiculme G. Meyer, Fl. Ksseq. 58. 1818.
Panicum leptomerum J. Presl, in Presl, Rel. Haenk. 1: 311. 1830.
Panicum diandrum Kunth, R6v. Gram. 393. 1831.
Panicum ramuliflorum Hochst.; Steud. Syn. Gram. 65. 1854.
Agrostis nigrescens Salzm.; Steud. Syn. Gram. 65. 1854.
Panicum nigrescens Salzm.; Steud. Syn. Gram. 66, as synonym. 1854.
Panicum Agrostis Nees; Doell, in Mart. Fl. Bras. 2 2 : 213, as synonym. 1877.
Panicum laxum pubescens Doell, in Mart. Fl. Bras. 2 2 : 213. 1877.
Panicum pilosum epilosum Fourn. Mex. PI. Gram. 24. 1886.
Plants more or less spreading, often rooting at the nodes of the decumbent base; culms simple or sparingly branching, 40-100 cm. high or more; leaf-sheaths shorter than the elongate internodes, ciliate and hirsute at the juncture with the blade, otherwise glabrous or papillosehirsute toward the summit; ligule fimbriate, about 0.5 mm. long; blades erect or ascending, conduplicate or flat, 10-25 cm. long, 5—15 mm. wide, rarely wider, narrowed to the rounded or subcordate base, glabrous or with a few scattered hairs on the upper surface; panicles oblong in outline, 5-30 cm. long, composed of many slender, raceme-like branches, the lower distant, spreading, sometimes as much as 10 cm. long, the upper ascending; branchlets very short, mostly secund on the lower side of the branches, bearing 2 or 3 spikelets, or a few toward the base of the lower branches 5-10 mm. long; spikelets 1.1-1.5 mm. long, about 0.7 mm. wide and as thick or thicker; first glume one third to half the length of the spikelet, subacute, 1-3-nerved; second glume slightly shorter than the sterile lemma, the latter subtending a palea of nearly equal length, this becoming subrigid at maturity forcing open the spikelet; fruit 1-1.1 mm. long, about 0.5 mm. wide.
Type locality: Jamaica.
Distribution: Mexico and the West Indies to Paraguay.

Annuals, Perennials, Terrestrial, not aquatic, Stems trailing, spreading or prostrate, Stems nodes swollen or brittle, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems compressed, flattened, or sulcate, Stem s branching above base or distally at nodes, Stem nodes bearded or hairy, 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 or blade keeled, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades lanceolate, Leaf blades 2-10 mm wide, Leaf blades 1-2 cm 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 an open panicle, openly paniculate, branches spreading, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or cu lm, Inflorescence branches more than 10 to numerous, Flowers bisexual, Spikelets pedicellate, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets with 2 florets, Spikelet with 1 fertile floret and 1-2 sterile florets, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating below the glumes, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequal, Glumes equal to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glumes 3 nerved, Glumes 4-7 nerved, Lemma similar in texture to glumes, Lemma 5-7 nerved, Lemma glabrous, Lemma apex truncate, rounded, or obtuse, Lemma awnless, Lemma margins inrolled, tightly covering palea and caryopsis, Lemma straight, Palea present, well developed, Palea about equal to lemma, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Ca ryopsis ellipsoid, longitudinally grooved, hilum long-linear.