Raleigh Ecological Services Field Office
Conserving the Nature of America

White Irisette (Sisyrinchium dichotomum)

White Irisette. Credit: USFWS

White Irisette. Credit: USFWS

Family: Iris (Iridaceae)

Federal Status: Endangered, listed September 26, 1991

Best Search Time: Late-May through July

Description: White irisette is a perennial herb that lives in areas with partial sun. It generally grows from 10 - 16 inches (25.4 – 40.6 centimeters) tall and has winged stems. An individual White irisette plant is typically defined as a cluster of stems arising from fibrous roots. There may be 10 or more stems on one plant. White irisette flowers from late May through July. The seeds are very small and black and three to six seeds are contained in each capsule.

Habitat: The species is found on mid elevation slopes, characterized by open, dry to moderate-moisture oak hickory forests. White irisette usually grows in shallow soils on regularly disturbed sites (such as woodland edges and roadsides) and over rocky, steep terrain.

map of White Irisette distribution in North Carolina

Map of White Irisette distribution in North Carolina.

Distribution: White irisette is known from Henderson, Polk and Rutherford Counties, North Carolina; and Greenville County, South Carolina.

Threats: White irisette is threatened by many human caused disturbances, such as residential development, road construction, and possibly herbicide use. It is also indirectly affected by the extirpation of elk and bison and possibly the suppression of fire. The elimination or suppression of these natural disturbances allows vegetative succession to occur, often accompanied by exotic invasive plants that out compete this native species.

References:

Buchanan, M.F. and J.T. Finnegan. 2010. Natural Heritage Program List of the Rare Plant Species of North Carolina. N.C. Natural Heritage Program, Raleigh, NC.

U.S. Fish and Wildlife Service. 1995. White Irisette Recovery Plan. U.S. Fish and Wildlife Service, Atlanta, Georgia. 22 pp.

For More Information on White Irisette...

Species Contact:

Mara Alexander, Fish and Wildlife Biologist, 828-258-3939 ext. 238

Species profile revised on September 15, 2011.

Last Updated: November 1, 2012