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Plant Profile

Cushenbury Milkvetch (Astragalus albens)

This small, silvery-white herb is a member of the pea family, a fact that is readily apparent when looking at its seed pods, as shown here. Photo Credit: Valerie Soza

Global Rank: G1 - Critically Imperiled
Legal Status: Federally Endangered
Family: Fabaceae
State: CA
Nature Serve ID: 159120
Lifeform: Forb/herb
Date Inducted in National Collection: 02/09/1992

Description:

Astragalus albens is a small, silvery-white, low-growing perennial herb of the pea family. It is a member of an increasingly rare suite of 5 endemic plant species restricted to carbonate deposits in the San Bernardino Mountains of southern California. This attractive plant blooms March-May, producing 5-14 purple flowers at the tips of the stems, which grow to about 1 foot (30 dm) in diameter. Cushenbury milkvetch is a federally-listed endangered species, with nearly all of its sites located on land that is actively mined or maintained for future mining (USFWS 1997).

Where is Cushenbury Milkvetch (Astragalus albens) located in the wild?

Habitat:

This species is found on cobbly/gravelly soils derived from decomposing limestone bedrock on gentle slopes and in rocky washes that have received limestone outwash. It grows in habitats with open canopies, low competition, and little organic material. Primary associated communities are pinyon-juniper woodlands with blackbush or flannelbush, and blackbrush scrub between 5,000 and 6,600 feet (1,500-2,000 m) elevation (USFWS 1994, 1997).

Distribution:

It is distributed over a 15 mile (24 km) stretch on the north side of the San Bernardino Mountains (Transverse Ranges), San Bernardino County, California, from Furnace Canyon southeast to Arrastre Cre

States & Provinces:

Cushenbury Milkvetch can be found in California

Which CPC Partners conserve Cushenbury Milkvetch (Astragalus albens)?

California Botanic Garden

Not Sponsored

Conservation Actions

Assigned 06/09/17

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

Cheryl Birker

11/19/2021

The California Botanic Garden made a conservation seed collection from a population of Astragalus albens (Cushenbury milkvetch) located near Baldwin Lake in the San Bernardino Mountains of San Bernardino County, California on June 3, 2021. This is a recollection of the 1995 seed collection made by Michael Gonnela (CalBG Accession #20919), and a seed sample was sent to the National Laboratory for Genetic Resources Preservation for use in the CPC/IMLS RNA Integrity Study.

Center for Plant Conservation

08/17/2021

In 2021, CPC contracted the California Botanic Garden to recollect seed from a population currently held in long term orthodox seed storage as part of an IMLS-funded seed longevity experiment. The National Laboratory for Genetic Resources Preservation will evaluate how germination tested viability and RNA Integrity of seed lots decline over time in storage.

09/01/2020

Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 5 accessions of Astragalus albens in orthodox seed collection. There are as many as 5253 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

08/05/2020

Based on an August 2020 extract of the California Plant Rescue Database, California Botanic Garden has collected 2 seed accessions of Astragalus albens from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 25 maternal plants

Nature Serve Biotics

05/02/2017

Restricted to a carbonate belt in the northeastern San Bernardino Mountains, San Bernardino County, California. Approximately 16 occurrences are believed extant (with another 2 historical and 1 of unknown status) within an area of approximately 80 square kilometers. Population size was estimated to be 7000-7500 plants, but is likely less in drought years. Habitat destruction and degradation associated with limestone mining is the major threat to this species. Other threats include off-highway vehicle use, target shooting, road building and maintenance, trash dumping, and potential development. The U.S. Fish and Wildlife Service (2002) has designated Critical Habitat and the U.S. Forest Service has developed the Carbonate Habitat Management Strategy (2003) with the aim of mitigating these threats.

Valerie Soza

01/01/2010

Threats and disturbances to the natural habitat of carbonate endemic plants within this region are primarily associated with limestone mining and include destruction of habitat by open or terraced mining techniques and quarries and associated overburden d

Valerie Soza

01/01/2010

Cushenbury milkvetch is known from 30-50 small occurrences with a total estimate of 2,000-7,000 individuals. Sizes of populations fluctuate with rainfall patterns, with larger-sized populations in years of substantial rain (USFWS 1997; Soza pers. comm.).

Valerie Soza

01/01/2010

Research has been conducted on habitat characteristics of this particular species in the San Bernardino Mountains with respect to restoration potential (Gonella and Neel 1993).

Valerie Soza

01/01/2010

The majority of carbonate deposits within the San Bernardino Mountains are owned by the USDA Forest Service, San Bernardino National Forest (SBNF), which has developed a forest management plan that aims to conserve some of the existing populations of the carbonate endemics by setting aside refugia. As part of this plan, the SBNF has supported ongoing surveys of carbonate habitat within the SBNF to expand knowledge of species distribution patterns and assist in identification of refugia potential (USFWS 1997).

Valerie Soza

01/01/2010

Management needs that have been identified by the USFWS include protection of significant extant populations by developing a reserve system on federally owned land of occupied areas, buffer zones, and habitat connections; restoring habitat, reintroduction efforts and enhancing populations; monitoring populations; and conducting surveys and taxonomic assessments to locate new populations and resolve questions about the identity of several existing populations (USFWS 1997).