Regularity: Regularly occurring
Global Range: Limited to the southwestern corner of Oregon.
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
Comments: Wet, open, serpentine valley bottomlands; meadows, intermittent creeks, depressions, swales, ditches.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 21 - 80
Comments: 64 occurrences at 1km separation distance.
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: T3 - Vulnerable
Reasons: Although Limnanthes alba ssp. gracilis is limited in habitat and threatened by a variety of factors, occurrences and population numbers are fairly high. Afer the last assessment in 1997, 20+ populations and 50,000+ plants were discovered. Residential and commercial development has increased dramatically in areas where this subspecies occurs. Populations on public lands are subject to timber sale activities and cattle grazing. Impacts from off-road vehicles and road construction and maintenance affect both public and private populations.
Global Short Term Trend: Relatively stable to decline of 30%
Comments: Either stable or declining slightly.
Global Long Term Trend: Unknown
Degree of Threat: High
Comments: One of the larger populations (10,000+) has already been severely impacted by heavy equipment action from highway construction. Two of the 10,000+ populations are part of a timber sale. One of the other 10,000+ populations is on private property leaving only one of the larger populations so far unthreatened on public lands. Potential threats noted on the records are: cattle grazing, off-road vehicle use, mining claims and activities, agriculture conversion, road right-of-way activities, ditch construction and maintenance and competition from exotic weeds.