Vine Mesquite

Panicum obtusum H. B. K. Nov. Gen. & Sp1: 98. 1815
Panicum polygonoides C. Muell. Bot. Zeit. 19: 323. 1861.
Panicum repente Buckl. Prel. Rep. Geol. & Agr. Surv. Tex. App. 3. 1866.
Brachiaria obtusa Nash, in Britton, Man. 77. 1901.
Plants perennial, usually tufted from a more or less knotted rootstock, and producing widely creeping stolons, sometimes 2 meters long or more, with long internodes, and geniculate, swollen, conspicuously villous nodes, these often with a knob-like cluster of hairy scales at the base of the extravaginal, erect branches, the clusters produced sometimes when the branch is not developed; culms wiry, compressed, 20-80 cm. high, simple, usually decumbent at base, glabrous, the nodes glabrous; leaf -sheaths shorter than the internodes, glabrous, or the lower and those of the stolons sometimes villous; ligule membranaceous, about 1 mm. long; blades 3-20 cm. long, 2-7 mm. wide, erect, firm, usually involute-setaceous toward the tip, glabrous on both surfaces or sometimes with a few long hairs on the upper surface at the base; panicle usually short-exserted, 3-12 cm. long, about 1 cm. wide, the few, appressed, raceme-like branches densely flowered; spikelets short-pediceled along one side of a slightly flattened rachis, 3-3.8 mm. long, 1.5-1.8 mm. wide, and about 2 mm. thick, obovoid, blunt, glabrous, usually brownish; first glume nearly as long as the spikelet, 5 -nerved; second glume and sterile lemma subequal, 7-9-nerved, the lemma subtending a rather firm palea and a staminate flower; fruit 3-3.5 mm. long, 1.5-1.7 mm. wide, subacute, smooth and shining, but very obscurely pubescent at the apex.
Type locality: Near Guanajuato, Guanajuato. Distribution: Missouri to Arizona, and south to central Mexico.

Perennials, Terrestrial, not aquatic, Rhizomes present, Rhizome elongate, creeping, stems distant, Stolons or runners present, Stems nodes swollen or brittle, Stems erect or ascending, 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 solid or spongy, Stem internodes hollow, Stems with inflorescence less than 1 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, hispid or prickly, 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 blades mostly glabrous, Leaf blades scabrous, roughened , or wrinkled, Leaf blades glaucous, blue-green, or grey, or with white glands, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence with 2-10 branches, Inflorescence branches 1-sided, Flowers bisexual, Spikelets pedicellate, Spikelets sessile or subsessile, 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 equal or subequal, Glumes equal to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glumes 4-7 nerved, Lemma similar in texture to glumes, Lemma 5-7 nerved, Lemm a 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, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.

Hopia obtusa is a species of grass commonly known as vine mesquite. This plant was treated as Panicum obtusum until recently when more molecular and genetic material revealed new information about it. Hopia obtusa is now placed in the monotypic genus Hopia.