Plants perennial; densely or loosely cespitose, occasionally stoloniferous.
Culms 15-75 cm, erect or decumbent, sometimes branched basally, sometimes
branched aerially; nodes 3-6; internodes glabrous or sparsely
to densely pubescent with papillose-based hairs. Leaves basal or mainly
cauline; sheaths mostly glabrous, finely scabrous, or pubescent, pilose
near the ligules; ligules 0.2-0.5 mm, of hairs; blades 1-30 cm
long, 1-2.5 mm wide, flat to involute, papillose-based hairs often present on
both surfaces, usually present on the bases of the margins. Panicles
usually with 0.7-18 cm rachises bearing 1-6 branches, the branches sometimes
digitate; branches 10-40 mm, persistent, straight, with 20-50 spikelets,
axes extending 5-10 mm beyond base of the terminal spikelets; disarticulation
above the glumes. Spikelets pectinate, green to dark purple, with 1 bisexual
floret and 1-2 rudimentary florets. Glumes acuminate or awn-tipped; lower
glumes 1.4-3.5 mm; upper glumes 3-6 mm, midveins with papillose-based
hairs; lowest lemmas 2-4.5 mm, pubescent, 1-3-awned, central (or only)
awns 0.2-2.5 mm, not flanked by membranous lobes, lateral lobes acuminate, unawned
or with awns no longer than the central awn; lower paleas ovate, unawned;
anthers 2-3.4 mm, cream or yellow; rachilla internodes subtending
second florets glabrous or pubescent, sometimes with a distal tuft of hairs;
second lemmas 0.5-2 mm, bilobed, 3-awned, awns 2-4(6) mm; third lemmas,
if present, minute, membranous scales, glabrous. Caryopses 1.5-2.6 mm.
2n = 20, 40, 50, 60; numerous dysploid numbers also reported.
Bouteloua hirsuta is a widespread species, with two subspecies that frequently
hybridize in areas of sympatry (Wipff and Jones 1996).
Dr. David Bogler, USDA NRCS PLANTS Database
Perennials, Terrestrial, not aquatic, Rhizomes present, Rhizome short and compact, stems close, Stolons or runners present, 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, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly basal, below middle of stem, 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 very narrow or filiform, less th an 2 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades more or less hairy, Ligule present, Ligule a fringe of hairs, Inflorescence terminal, Inflorescence with 2 or more spikes, fascicles, glomerules, heads, or clusters per culm, Inflorescence a panicle with narrowly racemose or spicate branches, Inflorescence with 2-10 branches, Inflorescence branches 1-sided, Inflorescence branches terminating in bristle or point, Flowers bisexual, Spikelets sessile or subsessile, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, 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 equal to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glumes 1 nerved, Lemma coriaceous, firmer or thicker in texture than the glumes, Lemma 3 nerved, Lemma glabrous, Lemma body or surface hairy, Lemma apex dentate, 3-5 fid, Lemma mucronate, very shortly beaked or awned, less than 1-2 mm, Lemma with 1 awn, Lemma with 3 awns, Lemma awn less than 1 cm long, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea shorter than lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.
Densely tufted perennial 1.5-6 dm; lvs mostly crowded toward the base; sheaths pilose at the throat; blades flat, 1-3 mm wide; spikes 1-3, usually 2, straight or recurved,
2-4 cm; rachis projecting 2-5 mm beyond the uppermost spikelet as a straight stiff point; spikelets numerous, closely imbricate, divergent; first glume subulate; second glume lanceolate, 3-4 mm, densely papillose- hirsute on the prominent midvein; fertile lemma about equaling the second glume, sparsely villous throughout, its awn short and flattened; vestige long-stipitate, glabrous at base, obconic, often reaching the summit of the second glume, its 3 awns equal, exceeding the tips of the fertile lemma and second glume; 2n=12-50. Dry prairies and sand-hills; Wis. and Ill. to N.D., s. and w. to Tex., Calif., and Mex.; Fla.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.