White irisette
Sisyrinchium dichotomum

Status: Endangered

Description: White irisette is a perennial herb that lives in areas with partial sun. An individual white irisette plant is typically defined as a cluster of stems arising from fibrous roots. It generally grows from 10 to 16 inches tall and has winged stems. 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.

Range: 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.

Listing: September 26, 1991. 56 FR 48752 48755

Critical habitat: None designated

Why should we be concerned about the loss of species? Extinction is a natural process that has been occurring since long before the appearance of humans. Normally, new species develop (through a process known as speciation) at about the same rate other species become extinct. However, because of air and water pollution, forest clearing, loss of wetlands, and other human‑induced environmental changes, extinctions are now occurring at a rate that far exceeds the speciation rate.

All living things are part of a complex and interconnected network. We depend on the diversity of plant and animal life for our recreation, nourishment, many of our lifesaving medicines, and the ecological functions they provide. One-quarter of all the prescriptions written in the United States today contain chemicals that were originally discovered in plants and animals. Industry and agriculture are increasingly making use of wild plants, seeking out the remaining wild strain of many common crops, such as wheat and corn, to produce new hybrids that are more resistant to disease, pests, and marginal climatic conditions. Our food crops depend on insects and other animals for pollination.
Healthy forests clean the air and provide oxygen for us to breathe. Wetlands clean water and help minimize the impacts of floods. These services are the foundation of life and depend on a diversity of plants and animals working in concert. Each time a species disappears, we lose not only those benefits we know it provided but other benefits that we have yet to realize.

What you can do to help:
Tread lightly, and stay on designated trails. On some popular mountains, the vegetation has virtually been destroyed by human trampling.

Visit arboretums, botanical gardens, and parks to learn all you can about endangered plants and the causes of their decline.

Don’t collect or buy plants that have been gathered from wild populations.

Participate in the protection of our remaining wild land and the restoration of damaged ecosystems.

Be careful with the use and disposal of pesticides and other chemicals, especially near sensitive habitats.

Prepared by:
U.S. Fish and Wildlife Service
Asheville Field Office
160 Zillicoa Street 
Asheville, North Carolina 28801 
(828) 258‑3939

November, 2011