Metcalfia mexicana (Scribn.) Conert

Danthonia mexicana Scribn. Proc. Acad. Phila 1891:301. 1891.
Culms erect in dense hard tufts, 70-100 cm. tall; leaves aggregate at base, the sheaths firm, brown, the elongate blades involute, rather rigid, pungent, scaberulous; Hgule rather firm, 2-3 nun. long, the margins sometimes separating and forming auricles; panicle linear, strict, 10-20 cm. long, nearly simple, the rather remote appressed lower branches sometimes bearing 3 or 4 spikelets, the common axis scabrous; spikelets short-pedicelled, purphsh, 15-16 mm. long, 3-flowered or 4-flowered, the short rachilla-joints pilose; glumes 5-7-nerved, acuminate, shorter than the uppermost florets, the first 1 1-12 mm., the second about 13 mm. long; lemmas pilose except at the scabrous summit, 10-11 mm. long, including the firm acuminate awnless lobes; terminal segment of the awn 8-10 mm. long; palea notched, much shorter than the lemma.
Type locality : Cameros Pass, Coahuila {Pringle 3279) . Distribution: Limestone hills, Coahuila and Pucbla.