Nassella viridula (Trin.) Barkworth

Stipa viridula Trin. Mem. Acad. St.-Petersb. VI. 4^: 39. 1836
StipasparlaTiin.; Hook. Fl. Bor. Am. 2: 237. 1839. (No description; .5. pari'/^oi-a Nutt.. not Desf.
cited as synonym.) Stipa NuUalli'ana Steud. Nom. Bot. ed. 2. 2: 643. 1841. (Based on Stipa parviftora as described
by Nuttall (Gen. PI. 1: 59. 1818).)
Culms erect or sometimes geniculate at base, glabrous or scaberulous, mostly 60-100 cm. tall; sheaths glabrous, villous at the throat, often rather sparingly so, more or less hispidulous in a line across the collar, villous on the margin; ligule membranaceous, about I mm. long; blades flat or, especially on the innovations, involute, mostly scabrous, sometimes glabrous beneath, 10-30 cm. long, 1-3 or even 5 mm. wide; panicle narrow, greenish or tawny at maturity, 10-20 cm. long, the branches appressed or ascending, somewhat distant but usually overlapping, 2 or 3 at a node or branching near base and appearing fascicled, some short, one longer and naked below, 3-7 or even 10 cm. long, the lower nodes hispidulous; glumes 7-10 mm. long, about equal, narrowed above and extending into a slender tip as much as 3 mm. long, hyaline with green nerves, 3-nerved, scaberulous on the keel and sometimes on the lateral nerves; lemma 5-6 mm. long, fusiform, at maturity plump, more than 1 mm. wide, the callus rather blunt, about 0.5 mm. long, barbed with short whitish hairs, the body at maturity usually brown or brownish, rather sparingly villous all over with whitish appressed hairs, the surface roughened with minute papillae, the summit hispidulous with erect hairs 0.5-1 mm. long; awn 2-3 cm. long, twice geniculate, slender, scabrous, twisted to the second bend, the first segment 3-4 mm. long, the second usually a little longer, the third somewhat flexuous; anthers bearing at apex a few hairs.
Type locality: Saskatchewan.
Distribution: Plains and dry slopes, Wisconsin to Alberta, and southward to Kansas and New Mexico.