Welsh's Milkweed / Center For Plant Conservation
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Plant Profile

Welsh's Milkweed (Asclepias welshii)

In the foreground is Welsh's milkweed, growing on the beautiful pink sand dunes where the species is found. Photo Credit: Joyce Maschinski
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Threatened
  • Family: Apocynaceae
  • State: AZ, NN, UT
  • Nature Serve ID: 146639
  • Lifeform: Forb/herb
  • Date Inducted in National Collection: 04/04/1991
Description:

Welsh's milkweed is an herbaceous perennial with extremely hairy and broad ovate leaves. Cream-colored flowers with rose-tinged centers are produced in a ball shaped cluster from May to June. Large seeds with rudimentary tufts of hairs develop and are dispersed from July to early September. However, two other growth forms are known to exist. What is designated as the primary growth form has narrow linear leaves and looks very similar to A. subverticillata. A second form exhibits intermediate leaf traits of the primary form and the first description (referred to as the mature form) and is called the secondary form. (Palmer & Armstrong 2000) This species grows in coral pink colored sand dunes and was listed as threatened in 1987 in response to increased threats of off-road vehicle (ORV) activity (USFWS 1987).

Where is Welsh's Milkweed (Asclepias welshii) located in the wild?

Habitat:

A. welshii grows on active sand dunes in sagebrush, juniper, and ponderosa pine communities, between 4700 and 6250 ft in elevation. (NatureServe 2001)Co-occurring species include Wyethia scabra, Calamovilfa gigantea, Chrysothamnus nauseosus and Sophora stenophylla.

Distribution:

Kane Co., UT, near Kanab, and adjacent Coconino Co., AZ, near the Utah-Arizona state line.

States & Provinces:

Welsh's Milkweed can be found in Arizona, Navajo Nation, Utah

Which CPC Partners conserve Welsh's Milkweed (Asclepias welshii)?

  • The Arboretum at Flagstaff

    Sponsored
    Sponsors Add

    Bronze Sponsor

    Elisa Rios

    Conservation Actions
    Assigned 06/09/17

  • Red Butte Garden and Arboretum

    Not Sponsored
    Conservation Actions
    Assigned 01/08/24

  • National Laboratory for Genetic Resource Preservation (USDA-ARS)

    Not Sponsored
    Conservation Actions
    Assigned 01/08/24
    • 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

    Tina Stanley
    • 01/08/2024
      • Orthodox Seed Banking

    Red Butte Garden has sent at least 4,000 wild-collected seeds of Asclepias welshii to the USDA-ARS National Laboratory for Genetic Resources Preservation for long term storage.

    Tina Stanley
    • 01/08/2024
      • Seed Collection Orthodox Seed Banking

    Between 1988 and 2014, Red Butte Garden staff made 6 wild seed collections representing more than 8,000 seeds from 110 individuals of Asclepias welshii. 4,100 of these seeds are held in long term storage at Red Butte Garden.

    • 08/19/2020
      • Propagation Research

    Seed germination protocol has been determined, but cultivation for more than 2 years has been problematic. Further cultivation trials are needed.

    • 08/19/2020
      • Demographic Research

    Palmer and Armstrong (2000) have monitored two populations for 12 years. The species colonizes shifting dunes and tends to be outcompeted when dunes stabilize. The authors believe that education and enforcement of regulations to protect dune habitat from off-road vehicles has effectively helped to preserve the species. At the time of listing, there were thought to be no more than 11,000 individuals of this species, with populations scattered in a fairly localized area in Utah and on the Utah-Arizona state line. (USFWS 1987) There are now three Utah populations: Coral Pink Sand Dunes (ca. 10,000 individuals), 2) Sand Hills ( ca. 500 individuals), 3) Sand Cove (ca. 600 individuals). At least two others are known to exist near Page County, Arizona and in the Paria-Vermillion Cliffs Wilderness are near the Utah/Arizona border in Kane County, Utah and Coconino County, Arizona (Palmer & Armstrong 2000).

    Nature Serve Biotics
    • 05/02/2017

    Known from only six population areas with a total of approximately 20,000 above-ground stems (the number of genetic individuals is unknown). The known range includes Kane County, Utah, BLM land in Coconino County, Arizona, and Navajo Nation lands in Arizona (Navajo, Apache, and Coconino counties). The two Utah occurrences face the greatest threats, with parts of the species' very fragile sand dune habitat impacted primarily by off-road vehicle activity. The two Navajo Nation occurrences are smaller, but are relatively remote and are believed to have good to excellent viability. The two occupied areas on BLM land in Arizona are relatively remote, and not affected by ORV disturbance.

    Joyce Maschinski, Ph.D.
    • 01/01/2010

    As stated by the U.S. Fish and Wildlife Service at the time of listing (USFWS 1987), threats include: Off-road vehicles Drought

    Joyce Maschinski, Ph.D.
    • 01/01/2010

    At the time of listing, there were thought to be no more than 11,000 individuals of this species, with populations scattered in a fairly localized area in Utah and on the Utah-Arizona state line. (USFWS 1987) There are now three Utah populations: Coral Pink Sand Dunes (ca. 10,000 individuals), 2) Sand Hills ( ca. 500 individuals), 3) Sand Cove (ca. 600 individuals). At least two others are known to exist near Page County, Arizona and in the Paria-Vermillion Cliffs Wilderness are near the Utah/Arizona border in Kane County, Utah and Coconino County, Arizona (Palmer & Armstrong 2000).

    Joyce Maschinski, Ph.D.
    • 01/01/2010

    Palmer and Armstrong (2000) have monitored two populations for 12 years. The species colonizes shifting dunes and tends to be outcompeted when dunes stabilize. The authors believe that education and enforcement of regulations to protect dune habitat from off-road vehicles has effectively helped to preserve the species.

    Joyce Maschinski, Ph.D.
    • 01/01/2010

    BLM has monitored the species for the past 12 years and has been enforcing ORV regulations to protect dunes. (Palmer & Armstrong 2000)

    Joyce Maschinski, Ph.D.
    • 01/01/2010

    The possibility of creating new dune habitat adjacent to occupied habitat could be explored.

    Joyce Maschinski, Ph.D.
    • 01/01/2010

    Seed germination protocol has been determined, but cultivation for more than 2 years has been problematic. Further cultivation trials are needed.

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    Nomenclature
    Taxon Asclepias welshii
    Authority N. Holmgren & P. Holmgren
    Family Apocynaceae
    CPC Number 312
    ITIS 30325
    USDA ASWE3
    Duration Perennial
    Common Names Welsh's milkweed
    Associated Scientific Names Asclepias welshii
    Distribution Kane Co., UT, near Kanab, and adjacent Coconino Co., AZ, near the Utah-Arizona state line.
    State Rank
    State State Rank
    Arizona S1
    Navajo Nation 4
    Utah S1
    Ecological Relationships

    Photos

    In the foreground is Welsh's milkweed, growing on the beautiful pink sand dunes where the species is found. Photo Credit: Joyce Maschinski

    The leaves and seed pods of this milkweed. Photo Credit: Joyce Maschinski
    Pollinators
    Common Name Name in Text Association Type Source InteractionID
    Bees
    Leaf-cutting bees Anthidium rodecki Floral Visitor Link
    Honey bees Apis mellifera Confirmed Pollinator Link
    Bumble bees Bombus bifarius Confirmed Pollinator Link
    Centris bees Ceratina nanula Floral Visitor Link
    Sweat bees Dialictus albohirtus Floral Visitor Link
    Sweat bees Dialictus ruidosensis Floral Visitor Link
    Leaf-cutting bees Heriades timberlakei Floral Visitor Link
    Carpenter bees Xylocopa californica arizonensis Confirmed Pollinator Link
    Butterflies & Moths
    Brush-footed butterflies Euphydryas anicia hermosa Confirmed Pollinator Link
    Noctuid moths Euxoa aurulenta Confirmed Pollinator Link
    Other
    Sand wasps Bembix americana Floral Visitor Link
    Sand wasps Microbembex californica Floral Visitor Link
    Square-headed wasps Mimesa Floral Visitor Link
    Square-headed wasps Oxybelus californicus Floral Visitor Link
    Paper wasps Polistes dorsalis Floral Visitor Link

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