Piptatheropsis micrantha (Trin. & Rupr.) Romasch., P. M. Peterson & Soreng

Oryzopsis micrantha (Trin. & Rupr.) Thurber, Proc. Acad
Phila. 1863: 78. 1863.
Vrachne micraniha Trin. & Rupr. Mem. Acad. St.-Petersb. VI. T-: 16. 1842.
Culms densely tufted, with numerous innovations, erect, slender, scaberulous, 3-5-noded, 30-70 cm. tall; sheaths glabrous, longer than the internodes; ligule scarcely 1 mm. long; blade, slender, flat or, especally on the innovations, involute, often nearly as long as the culms scabrous, 2 mm. wide or less; panicle open, 10-15 cm. long, the branches distant, single or in pairs, spreading or finally reflexed, 2-5 cm. long, with short-pediceled appressed spikelets toward the ends; glumes thin, acuminate, 3-4 mm. long; lemma elliptic, glabrous and shining, rarely appressed-pilose, 2-2.5 mm. long, yellow or brown; awn more or less flexuous, 5-10 mm. long.
Typr locality: Saskatchewan.
Distribution: Open dry woods and rocky slopes, medium altitudes, Saskatchewan to Montana, south to New Mexico and Arizona. The form with pilose lemmas is found from Colorado to Arizona.

Perennials, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems erect or ascending, 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 middl e of stem, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades very narrow or filiform, less than 2 mm wide, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, 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 culm, 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 solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the floret s, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glumes 1 nerved, Glumes 3 nerved, Lemma coriaceous, firmer or thicker in texture than the glumes, Lemma 3 nerved, Lemma glabrous, Lemma apex truncate, rounded, or obtuse, Lemma distinctly awned, more than 2-3 mm, Lemma with 1 awn, Lemma awn less than 1 cm long, Lemma awned from tip, Lemma awns straight or curved to base, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea about equal to 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.