Iris cristata aka Crested Iris

Iris cristata, or dwarf crested iris, belongs to the iris family. This small perennial comes from north-central and eastern parts of America. It grows in woods, ravines, and on wooded slopes. Wild plants also occur on bluffs and near streams. In gardens, it makes a low cover beneath trees. Deer tend to leave it alone.

Plants often stand 0.25–0.5 feet [0.08–0.15 metres] tall. Some reach 0.75 feet [0.23 metres], while RHS gives a lower maximum. Garden clumps can spread to 1 foot [0.3 metres]. RHS lists a smaller spread of about 0.33 feet [0.1 metres]. Branching rhizomes help the plant spread and form mats. Narrow, sword-shaped leaves grow from these creeping stems. Leaves range from yellow-green to medium green. They reach about 0.5 feet [0.15 metres] long. The plant loses its leaves for winter.

The flowers sit on stems so short they seem absent. Their shades include pale blue, lilac, and lavender. White patches and gold or orange crests mark the falls. These are the outer parts of the iris flower. Missouri Botanical Garden records bloom in April. Chicago Botanic Garden gives May to June for its site. Flowers draw bumblebees and hummingbirds to the garden. Brown seed capsules follow, with fruit showing in June and July.

Part shade suits this iris best, though it accepts deeper shade. It grows well in moist soil with plenty of organic matter. Good drainage matters, and well-drained slopes can suit it. It also tolerates dry shade and some drought. Plants in full sun need soil that stays moist. Soil that is too rich can favour leaves over flowers. Sources place it in USDA zones 3–9 and RHS zone H6. Use it in shaded rock gardens, woodland beds, or borders. Its leaves provide ground cover after the flowers fade.

Slugs and snails can damage plants, and thrips may occur. RHS also lists soft rot, grey mould, and aphid-carried viruses. Divide rhizomes from midsummer through early autumn to make new plants. Remove dying leaves in autumn and spent stems after bloom. PFAF records past use of roots as a spice. It also lists folk remedies made from the roots. These reports do not establish safe use. RHS warns that eating this plant harms people and pets. Handling it may irritate skin, so wear gloves.