Stipa arabica Trin. & Rupr.

This is a widespread and variable species, reaching the eastern limit of its range in W China. It is sometimes subdivided into more narrowly defined species or infraspecific taxa based on variations in leaf indumentum and spikelet size. Chinese material is referable to subsp. caspia, or Stipa caspia at specific rank. Stipa arabica subsp. arabica from SW Asia has lemmas 7–9 mm and awns not exceeding 9 cm. Stipa turgaica is based on a form with densely pilose leaf blades. Stipa arabica is a good forage grass in desert steppe regions.

The frequently cited reference Stipa szowitsiana Trin. ex Hohen. in Bull. Soc. Nat. Moscou 11:243. 1838 is that of a nomen nudum and does not count for priority. Work is still needed on the infra-specific classification of Stipa arabica, but it seems that in Pakistan it is represented by subsp. caspia (C. Koch) Tzvelev in Nov. Sist. Vyssh. Rast. 11:16. 1974.

Perennial, tufted. Culms 40–80 cm tall, gray pubescent, 2–3-noded, nodes often dark-brown. Basal leaves 1/2 length of culms; leaf sheaths shorter than internodes, pubescent or lower part subglabrous; leaf blades filiform, convolute, outer surface glabrous to densely pilose; ligule lanceolate, 5–10 mm. Panicle contracted, 15–35 cm, base enclosed by slightly inflated uppermost leaf sheath. Spikelets pale green or greenish yellow; glumes narrowly lanceolate, 2–3 cm, membranous, apex long-acuminate; callus pungent, ca. 1 mm; lemma 9–12 mm, shortly hairy in longitudinal lines not reaching apex, a ring of hairs at awn articulation; awn 9–20 cm, deciduous, hairy throughout, 2-geniculate, column 1.5–1.8 cm to first bend, hairs ca. 1 mm, ca. 1.5 cm to second bend, bristle 6–7 cm, plumose on second column and bristle, hairs 1–2.5 mm. Fl. and fr. May–Jul.

Tufted perennial 30-70 cm high. Leaf-blades involute and setaceous, up to 2.5 mm wide when flattened, glabrous or densely pubescent on the lower (outer) surface; ligule 4-6 mm long. Panicle linear but not dense, 15-35 cm long, partially enclosed by the slightly inflated sheath of the uppermost leaf. Glumes narrowly lanceolate, long-acuminate, (20-)25-35 mm long, 3(-5)-nerved; lemma terete, 8-11.5 mm long (including callus), shortly hairy with rows of hairs not quite reaching the summit, with a crown of hairs at the tip; callus acuminate, pungent. Awn bigeniculate, articulated at the base, 10-16(-20) cm long; column shortly hairy (hairs 0.5-1.3 mm long); bristle plumose with hairs 2-4 mm long.

Xinjiang, Xizang [Afghanistan, Kazakhstan, Kyrgyzstan, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; SW Asia].

Distribution: Pakistan (Baluchistan & N.W.F.P.); Sinai eastwards through Iran, the Caucasus and Afghanistan to Pakistan and southern USSR.

Rocky slopes, Gobi desert; 500–3100 m.

Stipa arabica subsp. caspia (K. Koch) Tzvelev; S. arabica var. szovitsiana Trinius; S. arabica var. turgaica (Roshevitz) Tzvelev; S. caspia K. Koch; S. szovitsiana (Trinius) Grisebach; S. turgaica Roshevitz.