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Astragalus sinuatus

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Taxonomy [top]

Kingdom Phylum Class Order Family
PLANTAE TRACHEOPHYTA MAGNOLIOPSIDA FABALES LEGUMINOSAE

Scientific Name: Astragalus sinuatus
Species Authority: Piper
Common Name(s):
English Whited's Milkvetch
Synonym(s):
Astragalus whitedii Piper
Homalobus sinuatus (Piper) Rydb.
Homalobus whitedii (Piper) Rydb.
Phaca sinuata (Piper) Piper

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii) ver 3.1
Year Published: 2012
Date Assessed: 2010-04-08
Assessor(s): Contu, S.
Reviewer(s): Hilton-Taylor, C.
Justification:
Astragalus sinuatus is an endemic species which has an extremely small range (EOO = 25 km²) and for which much of the habitat within its historic range has been converted or significantly degraded by agriculture, grazing and gravel pits. There is still quite a bit of suitable habitat remaining, but the species does not seem to be able to spread in those areas and the causes are not fully understood at present. There are also ongoing threats to the species and the habitat such as fire suppression, non-native species invasions, grazing, and agricultural development. There is also a lack of comprehensive data on populations trends. This is clearly a species of conservation concern and is therefore proposed its listing is upgraded from Endangered to Critically Endangered.

Geographic Range [top]

Range Description: Astragalus sinuatus is endemic to the Chelan County, Washington State (US). The species is restricted to central Washington, along the western edge of the Columbia Basin, within a small creek drainage area.
Countries:
Native:
United States (Washington)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: In 1984 the population was estimated to be of 5,000 individuals, but no up to date data is currently available, but the populations might have decrease due to the threats to the species' habitat. A. sinuatus has been described as globally rare, but locally common in a collection in 2005 in Chelan County (Combs #15), but fieldwork and monitoring programs are necessary to make sure of the status and health of the species.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: A. sinuatus is a perennial herb which grows among sagebrush on rocky hillsides on predominantly south facing slopes at 250-610 m elevation. Grows in loess soils with small amounts of volcanic ash. Associated species include sulfur lupine (Lupinus sulphureus), desert yellowdaisy (Erigeron linearis), longleaf phlox (Phlox longifolia), woodsia (Woodsia oregana), balsamroot (Balsamorhiza sagittata), fernleaf desertparsley (Lomatium dissectum), bulbiferous fringecup, (Lithophragma bulbifera), and woolly-pod milkvetch (Astragalus purshii). Periodic fire (within a 30 to 90 year frequency interval) probably played a role historically in maintaining habitat for this species. However, fire today might promote weedy annuals at the expense of A. sinuatus.
Systems: Terrestrial

Threats [top]

Major Threat(s): The species' habitat is threatened by fire suppression, non-native species invasions, grazing, and agricultural development. Herbicide application for weed control may also pose a threat. The species itself is perhaps fairly resistant to disturbance. However, its natural habitat, in terms of ecological condition, is quite susceptible to grazing impacts (NatureServe 2009). A. sinuatus has been listed as probably present in the Rocky Reach reservoir and project (2000), therefore this population might be threatened by the project.

Conservation Actions [top]

Conservation Actions: There are no known conservation measures specifically for A. sinuatus, and the species is not currently known to occur within the protected areas network. Samples of seed of the species are stored in the Miller Seed Vault as part of the Washington Rare Plant Care and Conservation at the University of Washington Botanis Gardens. The species has been assessed as Critically Imperiled (G1) from NatureServe (2009), which is equivalent to IUCN category Critically Endangered (CR) or Endangered (EN), and as Endengered (E) in Washington State in the 1997 Red List of threatened Plants (1998).

Citation: Contu, S. 2012. Astragalus sinuatus. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 19 September 2014.
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