Regularity: Regularly occurring
Localities documented in Tropicos sources
United States (North America)
Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.
- Anonymous. 1986. List-Based Rec., Soil Conserv. Serv., U.S.D.A. Database of the U.S.D.A., Beltsville. http://www.tropicos.org/Reference/1103
- Munz, P. A. & D. D. Keck. 1959. Cal. Fl. 1–1681. University of California Press, Berkeley. http://www.tropicos.org/Reference/1717
- Munz, P. A. 1974. Fl. S. Calif. 1–1086. University of California Press, Berkeley. http://www.tropicos.org/Reference/1719
Global Range: Population occupies less than one hectare (USFWS 1995).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 5
Comments: Only one population left (USFWS 1995).
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: T1 - Critically Imperiled
Reasons: Known only from the type locality on Santa Rosa Island off the coast of southern California. The single population consists of about 2,000 plants. Grazing and trampling by (non-native) cattle were threatening the species, but an electric fence has been erected to protect the plants and the federally threatened western snowy plover (Charadrius alexandrinus nivosus). Cattle have periodically breached the fence, but the overall threat has diminished.
Comments: Removed from the USFWS list of species proposed as endangered due to the determination that it is only vulnerable to extinction due to random events, such as drought, and storms (July 31, 1997).