Iris phragmitetorum Handel-Mazzetti.
Rhizomes creeping, thick, ca. 1 cm in diam. Leaves grayish green, sword-shaped or broadly linear, 40--100 × 0.8--1.5 cm, midvein absent, base surrounded by maroon-brown fibers. Flowering stems 22--60 cm, solid; spathes 3--5, very unequal, 6--8 × 1--1.5 cm, 2--4-flowered, proximal ones shorter, apex usually acute, distal ones longer, apex usually obtuse. Flowers dark blue or violet, 9--10 cm in diam.; pedicel 1.5--3.5 cm. Perianth tube ca. 2 cm; outer segments obovate or elliptic, with a central, white or yellow zone, limb 7.5--9 × 4--4.5 cm; inner segments erect, oblanceolate, 5--6.5 × 0.8--1.5 cm. Stamens ca. 3 cm; anthers white. Ovary ca. 2 cm × 5--7 mm. Style branches 5--6 × ca. 1.2 cm; stigmas 2-lobed. Capsule ellipsoid-cylindric, 6.5--7 × 2--2.5 cm, apex not beaked. Seeds brown, semiorbicular, flat, ca. 6.5 × 5 mm. Fl. May--Jun, fr. Jul--Aug. 2 n = 32, 36*.
Banks of ponds and streams; 400--600 m (1900--3200 m in Yunnan). Heilongjiang, Jilin, Liaoning, Nei Mongol, Yunnan [Japan, Korea, Russia].
It is possible that the specimens from high elevations in Yunnan should be referred to Iris delavayi. It seems to one of us (Noltie) that I. laevigata in Yunnan is almost certainly only cultivated, though it perhaps becomes naturalized.
