Description from Flora of China
Iris tenuifolia Pallas var. thianschanica Maximowicz; I. thianschanica (Maximowicz) Vvedensky.
Plants forming hard tussocks. Rhizomes knobbly. Leaves linear, 20--40 cm × ca. 3 mm, rigid, midvein absent, base surrounded by maroon-brown, persistent sheaths. Flowering stems not or only slightly emerging above ground; spathes 3, 10--15 × ca. 1.5 cm, 1- or 2-flowered, midvein distinct, apex acuminate. Flowers pale violet, veined darker, 5.5--7 cm in diam. Perianth tube filiform, to 14 cm; outer segments oblanceolate or narrowly obovate, ca. 6 × 1--2 cm; inner segments oblanceolate, 4.5--5 cm × 7--8 mm. Stamens ca. 2.5 cm. Ovary ca. 1.2 cm. Style branches ca. 4 cm × 8 mm. Capsule subsessile, reddish brown, ovoid to cylindric, 4--7 × ca. 2 cm, 6-veined, apex shortly beaked. Fl. May--Jun, fr. Jul--Sep.
This species has usually been considered to be restricted to C Asia, and would therefore be expected to occur in China only in Xinjiang and W Xizang. Two of us (Noltie and Mathew) have seen no material from China, so the records from the other, more eastern provinces should be viewed with caution and are likely to refer to the doubtfully separable Iris tenuifolia.
Sunny grasslands, hillsides. Gansu, Nei Mongol, Ningxia, Qinghai, Sichuan, Xinjiang, Xizang [Afghanistan, Mongolia, Russia, Tajikistan; SW Asia (Iran)].