51. Ptilagrostis Grisebach in Ledebour, Fl. Ross. 4: 447. 1852.
细柄茅属 xi bing mao shu
Stipa sect. Ptilagrostis (Grisebach) Hackel.
Perennials, densely tufted. Culms slender, erect. Leaf blades setaceous. Inflorescence an open or loosely contracted panicle. Spikelets with 1 floret, bisexual, disarticulating above glumes; rachilla extension absent; glumes lanceolate to elliptic-oblong, subequal, a little longer than floret, herbaceous to scarious, 1–3-veined, apex obtuse to acuminate; callus short, obtuse, shortly bearded; lemma lanceolate, terete, papery, 3–5-veined, pubescent or pilose, margins not overlapping, apex minutely or distinctly 2-toothed, awned from between teeth; awn persistent, plumose throughout, 1(or 2)-geniculate, column twisted; palea midline exposed between lemma margins. Lodicules 3. Stamens 3, anthers glabrous or apex with hair tufts. Stigmas 2.
Eleven species: E Tajikistan (Pamirs) to Russia (NE Siberia), also W United States, on mountains; seven species (two endemic) in China.
Ptilagrostis pelliotii is a distinct and readily separable species, but most of the remainder of the genus comprises a complex of intergrading forms and local variants. The genus is weakly separated from Stipa, S. subsessiliflora being intermediate.
