Iris lacustris, the dwarf lake iris, is a plant species in the genus Iris, subgenus Limniris and in the section Lophiris (crested irises). It is a rhizomatous, beardless perennial plant, native to the Great Lakes region of eastern North America. It has lavender blue or violet-blue flowers, a very short stemand long fan-like green leaves. It is cultivated as an ornamental plant in temperate regions. It is closely related to Iris cristata (another North American crested iris).