Iris missouriensis is a clump-forming, deciduous, rhizomatous perennial belonging to the Iridaceae family of plants. It is also known as Iris tolmieana, Iris montana, Western Blue Flag, Rocky Mountain Flag, Missouri Flag, It is native to western North America and Mexico. The name missouriensis is in reference to the Missouri River where it was first discovered at the banks by Lewis and Clark, in 1806.
Iris missouriensis has long narrow sword-shaped leaves. It can grow to 50cm or 20in. It flowers in spring around May, June, and has pale lilac flowers but has strongly veined petals. Cut down flower stems after flowering. Each plant bears one to four flowers.
Grow Iris missouriensis in the sun or partial shade. Plant in slightly acid, fertile but well-drained soil. It tolerates wet soil and is considered a wetland plant. Propagate by division in autumn. Watch out for slugs, snails, thrips, and grey molds. It is deer-tolerant.
Native Americans have used Iris missouriensis in traditional medicine, for toothaches, the Navajo for emetic, and Zuni for strengthening babies.