CPC Plant Profile: Ventura Marsh Milkvetch
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Plant Profile

Ventura Marsh Milkvetch (Astragalus pycnostachyus var. lanosissimus)

Description
  • Global Rank: N/A
  • Legal Status: N/A
  • Family: Fabaceae
  • State: CA
  • Nature Serve ID: 134999
  • Date Inducted in National Collection: 09/01/2001

Less than 50 plants are known to exist, represented by a single population. The population occurs on an abandoned oil-field waste site, which has been proposed for reclamation and development as a residential community. Historic records suggest that this variety occurred near coastal marshes or bodies of brackish water, often on well-drained substrates near the water table. The current population occurs on an artificially compact substrate composed on clay, sand, and small gravels, above a water table that lies between 3 and 5 feet below the surface, and which is contaminated by oil wastes. Despite this seemingly inhospitable habitat, the population has remained relatively stable and plants have produced flowers and fruits during most of the years since its discovery in 1997.

Participating Institutions
Updates
  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden holds 16 accessions of Astragalus pycnostachyus var. lanosissimus in orthodox seed collection. There are as many as 3700 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 13 accessions of Astragalus pycnostachyus var. lanosissimus in orthodox seed collection. There are as many as 75735 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, National Laboratory for Genetic Resource Preservation (USDA-ARS) holds 1 accessions of Astragalus pycnostachyus var. lanosissimus in orthodox seed collection. There are as many as 150 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden has collected 20 seed accessions of Astragalus pycnostachyus var. lanosissimus from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 206 maternal plants

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, California Botanic Garden has collected 1 seed accessions of Astragalus pycnostachyus var. lanosissimus from 1 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass an unknown number of maternal plants

Nature Serve Biotics
  • 05/02/2017

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.

  • 01/01/2010

Herbivory by nonnative milk snails, which feed on seedlings and young vegetative shoots. Infestation by cucumber mosaic virus, which is vectored by aphids. Herbivory of seeds by weevils, which reduce seed set to less than 2 seeds in infested fruits.

  • 01/01/2010

Only one putatively natural population is left. It is in Oxnard, Ventura County, California. The remaining population has been composed of 30-50 reproductive plants per year, but as many as 300 vegetative plants have been observed during years with above normal precipitation and cool summers. Through efforts by the California Department of Fish and Game, small experimental populations have been established at four protected sites with comparable habitats in Santa Barbara and Ventura counties. The purpose of the experimental populations is to assess potential habitats for recovery, and to provide insurance against catastrophic loss.

  • 01/01/2010

Research conducted by the Santa Barbara Botanic Garden focused on reproductive biology and ecological requirements. Seedling cohorts show high mortality, especially from herbivory by snails, and during several seasons from below normal rainfall (Wilken and Wardlaw 2001). Research conducted by Rancho Santa Botanic Garden showed that seed germination is best accomplished through scarification, and that mature plants could be successfully transplanted, if provided sufficient water during the first season after planting. Survivorship of experimental populations was highest at sites with high water tables providing fresh or brackish water, as compared to salt water from nearby salt marshes (Soza et al. 2003).

  • 01/01/2010

The single remaining population is on privately owned land and has been fenced to protect it from accidental incursion by vehicles or individuals. Weed removal, snail abatement, and other protective measures are being conducted by volunteers and Department of Fish and Game staff. Experimental populations are protected by their location on state park lands, and their location at sites that are infrequently used by the public.

  • 01/01/2010

Protection and augmentation of experimental populations. Genetic analysis of natural and experimental populations. Surveys for additional recovery sites.

  • 01/01/2010

Augmentation of the conservation collection through managed cultivation of genetic lineages derived from separate plants at the original site.

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Nomenclature
Taxon Astragalus pycnostachyus var. lanosissimus
Authority Munz & McBurney
Family Fabaceae
CPC Number 475
ITIS 192732
USDA ASPYL
Common Names Ventura marsh milkvetch | marsh milkvetch | Ventura marsh milk-vetch
Associated Scientific Names Astragalus pycnostachyus var. lanosissimus | Phaca lanosissima
Distribution Known only from a single, self-sustaining population in Oxnard, Ventura County, California. Historical records indicate the occurrence of as many as 4 or 5 sites along the coast between Ventura and Or
State Rank
State State Rank
California S1
Habitat

Well-drained soils of open sites in coastal habitats, often on bluffs or flats near bodies of brackish water or with a relatively high water table, in association with dune or coastal shrubland vegetation. The distribution of the closely related northern marsh milkvetch (Astragalus pycnostachyus var. pycnostachyus, historic records, and the location of the single known population suggests that this species may survive where summer fog ameliorates the otherwise hot summers.

Ecological Relationships

They include well-drained soils of open sites in coastal shrublands or dune swales, near bodies of fresh or brackish water. Associated native species include Baccharis pilularis, Malosma laurina, and Toxicodendron diversilobum. The single known population is found in close proximity to the coast, where summer fog ameliorates the otherwise dry, warm to hot days.

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Honey bees Apis mellifera Suspected Pollinator Floral Link
Bumble bees Bombus Floral Visitor Link
Carpenter bees Xylocopa Suspected Pollinator Floral Link
Butterflies & Moths
Skippers Hesperidae Floral Visitor Link
Blues Lepotes marina Suspected Pollinator Floral Link
Hairstreaks Strymon melinus Suspected Pollinator Floral Link

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