Iris tenax

Iris tenax (Iridaceae) is a rhizomatous iris native to the coastal and interior lowlands of Oregon and adjacent portions of Washington and northwestern California, where it colonizes roadsides, grasslands, and forest openings at low to middle elevations. The very slender leaves (seldom exceeding 5 mm wide) are easily mistaken for grass when the plant is not in bloom. It spreads slowly by rhizomes.

Tough-leaved iris blooms mid to late spring in colors ranging from the typical lavender-blue to purple, with white, yellow, pink, and orchid forms also occurring. The species has received RHS recognition. Its narrow, grassy foliage makes it a natural fit for meadow plantings and mixed perennial borders. The common name references the tough, fibrous leaf tissue. Plants establish slowly but persist well in well-drained sites.