Astragalus pycnostachyus var. lanosissimus

Historically known from Ventura, Los Angeles, and Orange counties in coastal southern California. Now known from one, less than one acre naturally-occurring site in Ventura County. There are also four introduction sites, two in Ventura County and two in Santa Barbara County (which is outside the historic range of this taxon). As yet, it is unclear whether these introductions will persist and become self-sustaining populations. Both the natural and introduced sites have substantial issues with non-native invasive weeds. Herbivory by small mammals and/or non-native snails is also an issue at some sites. In addition, the naturally-occurring site may be threatened by hydrological alteration associated with soil remediation activities and surrounding residential development.

Historically, Ventura to Orange County, California; along the coast in salt marshes. Currently known from one naturally-occurring site in Ventura County (U.S. Fish and Wildlife Service 2001). There are also four introduction sites, two in Ventura County and two in Santa Barbara County (which is outside the historic range of this taxon) (M. Meyer pers. comm. 2010).

Most historical or extirpated; one naturally-occurring site discovered in Ventura County in 1997 (U.S. Fish and Wildlife Service 2001). The presumption is that the original source of seed at this site came from some either onsite or nearby top soil brought in to cap the oil waste facility when it closed in 1982 (M. Meyer pers. comm. 2010). There are also four introduction sites, two in Ventura County and two in Santa Barbara County (which is outside the historic range of this taxon). As yet, it is unclear whether these introductions will persist and become self-sustaining populations (M. Meyer pers. comm. 2010).

Both the natural and introduced sites have substantial issues with non-native invasive weeds. Herbivory by small mammals and/or non-native snails is also an issue at some sites.

The naturally-occurring population has experienced alterations in the surrounding topography and subsurface oil layers outside the 1.6 acre unremediated exclosure area as a result of recent (2007) remediation of subsurface oil contaminants, site grading, disposal of wastes beneath artificially constructed and lined dunes, and other topographic alterations. Additionally, very low rainfall has occurred in two of the last three recent years. Few fruits form when moisture becomes limiting during the flowering period and plant vigor appears reduced (M. Meyer pers.comm. 2010). The relationship between natural stochastic declines, weather-related effects and remediation remains poorly understood. Additional evaluations are being undertaken to better understand and address this issue. A temporary watering system was installed in late July 2009 by the biological consultants now overseeing the remediation and site restoration activities. This system was installed with input from a team of milkvetch science advisors. This system appears to have successfully prevented some or all of the adult plants from dying due to dessication from loss of soil moisture. 2009 flowering and fruit production had already been compromised by the time irrigation system was functional, however. Soil remediation at the site is now technically complete, although some ongoing cleanup of volatiles via an air filtration system is still operating just outside the population exclosure. The site is approved for residential development of the surrounding area and will include a milkvetch preserve inside a restored dune system. The site has been graded, and streets laid out. The project has reverted to a bank, and currently, home construction is delayed due to economic conditions.