Stipagrostis Nees in Linnaea. 7:290. 1832. Henrard in Meded. Rijks-Herb. No. 58. 1929; De Winter in Bothalia 8:307. 1965; Bor in Towns., Guest and Al-Rawi, Fl. Iraq 9:386. 1968; Bor in Rech. f., Fl. Iran. 70:368. 1970; Tzvelev, Poaceae URSS 616. 1976; Tutin in Tutin et al., Fl. Eur. 5:254. 1980.
Densely tufted perennials, suffrutices with knotty rhizomatous base, or delicate annuals. Leaf-blades narrow or terete, sometimes early deciduous leaving sheaths and chlorophyll-bearing culms as the main photosynthetic organs. Panicle open or contracted. Spikelets 1-flowered with scarious glumes; lemma cylindrical; indurated, produced into a 3-branched awn; awn with or without a column, articulated at the base of the column or near the middle of the lemma, the branches, or at least the central one plumose; callus well-developed, pungent or minutely bifid, usually oblique; palea usually less than half as long as the lemma.
A genus of about 50 species in dry or desert regions of Africa and the Middle East to Northwest India; 7 species occur in Pakistan.
Stipagrostis is readily distinguished by its plumose awns. Its separation from Aristida is supported by the following anatomical characters:
Aristida. Cells of outer bundle-sheath smaller than the inner, both sheaths containing chloroplasts; silica-bodies usually dumb-bell-shaped; chromosome number usually 2n=22.
Stipagrostis. Cells of outer bundle-sheath larger than the inner, only the inner containing chloroplasts; silica-bodies usually circular; chromosome number usually 2n=44.
