Osterhout's Milkvetch / Center For Plant Conservation
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Plant Profile

Osterhout's Milkvetch (Astragalus osterhoutii)

View of this tall plant with numerous upright stems. Photo Credit: Carol Dawson
  • Global Rank: G2 - Imperiled
  • Legal Status: Federally Endangered
  • Family: Fabaceae
  • State: CO
  • Nature Serve ID: 155315
  • Lifeform: Forb/herb
  • Date Inducted in National Collection: 02/10/1987
Description:

Osterhout milkvetch grows in high-selenium soils. Selenium is concentrated in its plant tissue, producing an unpleasant odor (Dornbirer 1995). The plant is a tall, herbaceous perennial with rush-like stems. It produces numerous cream-colored flowers. A significant part of the known range and population was lost when a new reservoir was filled on the Muddy Creek in 1995. (Von Bargen 1997)

Where is Osterhout's Milkvetch (Astragalus osterhoutii) located in the wild?

Habitat:

Highly seleniferous, grayish-brown clay soils derived from shales of the Niobrara, Pierre and Troublesome formations (USFWS 1998, 1989, 1992). On moderate slopes, sometimes growing up through sagebrush at elevations of 7400-7900 feet. The milkvetch is found in badlands of shale and siltstone barrens in high elevation sagebrush habitat. (Spackman 1997).

Distribution:

Colorado endemic (Muddy and Troublesome Creek drainages, Grand Co.). (Spackman 1997)

States & Provinces:

Osterhout's Milkvetch can be found in Colorado

Which CPC Partners conserve Osterhout's Milkvetch (Astragalus osterhoutii)?

  • Denver Botanic Gardens

    Sponsored
    Sponsors Add

    Silver Sponsor

    Andrew W. Mellon Foundation

    Denver Botanic Garden

    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

    Alexandra Seglias
    • 10/28/2024

    Seed was collected in 2024 and is held at Denver Botanic Gardens.

    • 08/26/2020
      • Propagation Research

    The populations surrounding Kremmling, CO have been monitored by Denver Botanic Gardens since 1993. Additionally, a habitat manipulation experiment was conducted to test the establishment of seeds and seedlings under soil disturbance and sagebrush removal. Seed has been collected for storage and propagation studies.

    • 08/26/2020
      • Orthodox Seed Banking

    Maintain a seed bank that represents the genetic diversity of the species. Seed has been collected for storage and propagation studies.

    • 08/26/2020
      • Seed Collection

    Maintain a seed bank that represents the genetic diversity of the species. Seed has been collected for storage and propagation studies.

    Nature Serve Biotics
    • 05/02/2017

    Endemic to small area in Grand County, Colorado, mostly near a single creek. Construction of a dam in 1995 flooded at least 1 occurrence and impacted others. Other threats to this species include off-road vehicles, road maintenance, oil and gas drilling, and mining.

    Carol Dawson
    • 01/01/2010

    Off-road vehicle use, mineral exploration, Muddy Creek Reservoir recreational development, private development stimulated by the construction of the reservoir. (Von Bargen 1997)

    Carol Dawson
    • 01/01/2010

    Occurs in scattered colonies over a 15 mile range with ca. 25,000-50,000 individuals. (USFWS 1989, Von Bargen 1997)

    Carol Dawson
    • 01/01/2010

    The populations surrounding Kremmling, CO have been monitored by Denver Botanic Gardens since 1993. Additionally, a habitat manipulation experiment was conducted to test the establishment of seeds and seedlings under soil disturbance and sagebrush removal. Seed has been collected for storage and propagation studies.

    Carol Dawson
    • 01/01/2010

    Since the time of listing, the Bureau of Land Management has initiated habitat purchases, land exchanges, and formal land management designations (including Areas of Critical Environmental Concern) for this species. (USGS 2002)

    Carol Dawson
    • 01/01/2010

    Continue research to determine best habitat management practices for this species. Negotiate with habitat owners and managers to put best management practices in place. Continue monitoring to get more data on reproductive success and population trends.

    Carol Dawson
    • 01/01/2010

    Maintain a seed bank that represents the genetic diversity of the species.

    MORE

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    Nomenclature
    Taxon Astragalus osterhoutii
    Authority M.E. Jones
    Family Fabaceae
    CPC Number 461
    ITIS 25618
    USDA ASOS
    Duration Perennial
    Common Names Osterhout milkvetch | Kremmling milkvetch | Osterhout's milk-vetch | Osterhout milk-vetch | Kremmling milkvetch
    Associated Scientific Names Astragalus osterhoutii | Lonchophaca osterhoutii
    Distribution Colorado endemic (Muddy and Troublesome Creek drainages, Grand Co.). (Spackman 1997)
    State Rank
    State State Rank
    Colorado S1
    Ecological Relationships

    Photos

    View of this tall plant with numerous upright stems. Photo Credit: Carol Dawson

    Close-up of the creamy white flowers characteristic of this species. Photo Credit: Carol Dawson

    Photo Caption

    Photo Credit: Alex Seglias
    Pollinators
    Common Name Name in Text Association Type Source InteractionID
    Bees
    Polylectic bees Confirmed Pollinator Link

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