Rhizomes obscure. Roots thick. Leaves in basal fans, grayish green, sword-shaped, slightly curved, 22--40 × 1.1--2 cm, midvein absent, base surrounded by brown fibers. Flowering stems 2--5-branched, 25--40 cm, bearing only reduced leaves; spathes 3--5, green, 2.5--3.5 cm, 2--4-flowered. Flowers pale bluish to violet, 4.5--5 cm in diam.; pedicel exserted from spathes, 3--4 cm, stiff, persistent. Perianth tube ca. 2 cm; outer segments oblanceolate, ca. 4 × 7 cm; inner segments narrowly oblanceolate, ca. 3 cm × 4 mm. Stamens ca. 2.2 cm. Ovary ca. 1.5 × 0.5 cm. Style branches ca. 3 cm. Capsule cylindric, 5--6 × ca. 1 cm, 6-ribbed. Seeds maroon-brown, 7.5--8.5 mm, with small wings. Fl. Jun--Aug, fr. Jul--Sep.

After publication of the FOC treatment, a new white-flowered form was reported (i.e., Iris subdichotoma f. alba Y. G. Shen, Acta Bot. Yunnan. 26(5): 492. 2004).

* Grasslands, open hillsides or banks near riversides; 1800--2700 m. NW Yunnan.