Species Overview

Native to: Europe

Yellowflag iris is a wetland plant that is especially showy during its short blooming period. Its beauty has led to it being a popular water garden ornamental and it has widely escaped cultivation.

Species Characteristics

Family: Iridaceae

Habit: Perennial emergent aquatic forb

Leaves: Erect with upper part arching; leaves flattened, arising in a fan from the soil; raised midrib; sword-like, fine-pointed; 3-4 feet in height.

Flowers: On erect stalks (peduncles) 3-4 feet in height; bisexual; large, showy, pale to deep yellow; the only yellow iris in the U.S.; several flowers on each stem; flowers having 6 clawed perianth segments including 3 large downward-spreading sepals and 3 smaller erect petals; on each flower sepal (yellow, large and petal-looking) are patterns of delicate light-brownish to purple veins or flecks.

Fruit/Seeds: Capsule (seed pod); large (4-8 cm, (to 4 in.)), 3-angled cylindrical, glossy green; many flattened brown seeds.

Distribution in Florida: Vouchered from Jackson, Liberty, Gadsden, and Leon counties.

Note: Easily confused with native Iris species when not in bloom.

Impacts

Individuals produce from several dozen to several hundred rooted rosettes and flowering shoots connected by durable rhizomes. This fast growing and rapidly spreading plant can form dense, almost impenetrable thickets, outcompeting native vegetation.

Do not plant. Clean boating and recreational equipment before leaving a water body.

Hand pull small plants ensuring all plant and rhizome material are removed. Plastic tarps have been used in small patches with woven plastic and landscape fabric providing the most efficacy.

May be effective on small populations, but all plant and rhizome material must be removed.

Not likely to be feasible given the many closely related native and ornamental species.

See weed report from the Weed Control in Natural Areas in the Western United States. Consult your local UF IFAS Extension Office for management recommendations.