Tobosagrass

Pleuraphis mutica BuckL Proc. Acad. Phila. 1862 : 95. 1862
Hilaria mutica Benth. Jour. Linn. Soc. 19: 62. 1881.
Stems 2-6 dm. tall, simple, erect, smooth or sometimes rough below the puberulent nodes; leaves glabrous or hirsute, smooth or rough, confined mainly to the lower portion of the stem; sheaths overlapping; blades up to 8 cm. long, sometimes longer on the innovations, 2-4 mm. wide, erect or ascending, usually involute on the margins; inflorescence 3.5-7 cm. long, the axis glabrous, sometimes hispidulous on the angles; spikelet-clusters 5.5-7.5 mm. long, 3-4 times as long as the basal hairs; lateral spikelets with the empty scales inequilateral, long-ciliate on the margins, 2-lobed, the first scale longer than the second, cuneate, flabellately 5or 6-nerved, the midnerve excurrent as a hispid awn between the lobes, one lobe so small that it resembles a lateral appendage on the inner side of the scale, the second scale linearoblong, 4or 5-nerved, the parallel nerves all vanishing below the apex, none of them excurrent, the flowering scales 2 or 3, long-ciliate at the 2-lobed apex, the lobes rounded, 2or 3-nerved, one lateral nerve sometimes being suppressed, the midnerve terminating -at the sinus, the lateral nerves vanishing below the apex; central spikelet with the empty scales 2-lobed, longciliate on the margins above, equilateral, the apex divided into about 4 awns or awned lobes, the midnerve usually excurrent below the middle as a hispid awn shorter than the scale, the flowering scale 3-nerved, the lateral nerves vanishing below the apex, the midnerve excurrent
between the obtuse lobes as a short hispidulous awn.
Type locality : Northern Texas.
Distribution : Western Texas to California, and south to Durango and I^wer California.

Perennials, Terrestrial, not aquatic, Rhizomes present, Rhizome short and compact, stems close, Stems nodes swollen or brittle, Stems erect or ascending, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems branching above base or distally at nodes, 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 at summit, throat, or collar, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, 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 a dense slender spike-like panicle or raceme, branches contracted, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence a panicle with narrowly racemose or spicate branches, Inflorescence bra nches more than 10 to numerous, Inflorescence branches 1-sided, Flowers bisexual, Flowers unisexual, Spikelets sessile or subsessile, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets with 3-7 florets, Spikelets 3 per node, Spikelets with 1 terminal fertile floret and 2 lateral staminate or sterile florets, Spikelets bisexual, Spikelets unisexual, Spikelets falling with parts of disarticulating rachis or pedicel, Inflorescence branches deciduous, falling intact, Spikelets secund, in rows on one side of rachis, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequal, Glumes shorter than adjacent lemma, Glumes equal to or longer than adjacent lemma, Glumes awned, awn 1-5 mm or longer, Glumes keeled or winged, Glumes 4-7 nerved, Glumes 2-5 toothed, Glume saccate, inflated, or flabellate, Glume margins or apex erose-ciliate, Glumes prominently lobed, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 3 nerved, Lemma glabrous, Lemma apex dentate, 2-fid, Lemma awnless, Lemma mucronate, very shortly beaked or awned, less than 1-2 mm, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea about equal to lemma, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.

Hilaria mutica, synonym Pleuraphis mutica, is a species of grass known by the common name tobosa, or tobosa grass. It is native to Northern Mexico, and the Southwestern United States, in Arizona, New Mexico, Oklahoma, and Texas.