Yellow Flag Iris


Yellow flag iris is a perennial, aquatic, herbaceous plant which grows 2 to 3 feet tall along shores in shallow water. Rhizomes spread and form large clumps. Flowers are pale to dark yellow with brownish purple mottled markings, have 3 sepals and 3 petals, with petals shorter than sepals. Yellow iris has gradually tapering sword-like leaves up to three fourths of an inch wide, dark green to blue-green in color. It is most commonly found in very shallow water or mud.  It tolerates drying and anoxic sediment and is also tolerant of some salinity, and high soil acidity. Up to several hundred flowering plants may be connected through rhizomes. Rhizome fragments can form new plants if they break off and drift to suitable habitat.


For smaller populations, hand removal is possible. If pulling or digging yellow iris, care should be used to protect the skin as resins in the leaves and rhizomes can cause irritation. Because rhizome fragments can grow to form new plants, all rhizome fragments must be carefully removed. The “cut-and-dab” method an also be used for worse infestations.