CPC Plant Profile: Mulford's Milkvetch
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Plant Profile

Mulford's Milkvetch (Astragalus mulfordiae)

Chuck Wellner shows off the long taproot of Astragalus mulfordiae. Photo Credit: Roger Rosentreter
Description
  • Global Rank: G2 - Imperiled
  • Legal Status: N/A
  • Family: Fabaceae
  • State: ID, OR
  • Nature Serve ID: 142398
  • Date Inducted in National Collection: 03/08/1989

Mulford's milk vetch is in danger of being ignored out of existence. Like many other species not particularly attractive to the general public, Astragalus mulfordiae does not get the attention that it deserves. While this plant may not qualify beautiful by the average member of the public, does not cure cancer, and is not found in a highly populated area, it does play an important role in its native ecosystem and is no less deserving of protection than a beautiful lily. There appear to be many populations, but many, especially in Idaho, occur on privately owned land, much of which is grazed. In Idaho, 18 of the 34 known populations (over half) occur entirely on private land. Only 8 populations occur entirely on Federal land. Plants in Oregon have had better luck. Until 1988, only one population was known in Oregon. As of 1995, 38 are known, 33 of which are on Bureau of Land Management property, and 5 of which are on Private land (DeBolt 1995). Why is it worrisome that so many populations in Idaho are on private land Those populations on private land are not subject to laws or regulations that the federal or state government may make in regards to this rare species.

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Updates
  • 08/26/2020
  • Propagation Research

Monitoring studies have been conducted at several sites in Oregon, and show evidence of drastic declines in population sizes. Individuals that were grazed by cattle were weakened in the second year and absent in the third year. However, there was no control treatment, and so it cannot be concluded that livestock alone are responsible for the decline (DeBolt 1995). Micropropagation techniques using seeds and shoot-tip explant in culture has been explored by Edson (1998). Astragalus mulfordiae seedling establishment, adult survival and reproduction were studied at two populations between 1995 and 1997. The effects of re-vegetation (seeding) with Agropyron desertorum (or A. cristatum) and the impacts of cattle grazing on the demography of A. mulfordiae were observed. Using a visual estimate of grazing severity per plant, those plants in the seeded area that was exposed to cattle grazing were grazed more severely than the un-seeded area that had light horse grazing. Fruits per inflorescence, inflorescence per plant and adult plant survival were all significantly lower in the cattle-grazed area (David Pyke, personal communication).

  • 08/26/2020
  • Propagation Research

Germination trials at The Berry Botanic Garden indicate no specific requirements. Seeds were scarified and then subjected to cold stratification or no cold stratification and were then placed in germination chambers with constant 68F (20C) temperatures or alternating 50F/68F (10/20C) temperatures. Several treatments resulted in 100% germination (BBG File). Pollination studies (Idaho BLM) (DeBolt 2001).

  • 08/26/2020
  • Demographic Research

As of 1995, 34 populations in Idaho, and 38 in Oregon. (DeBolt 1995) Population sizes in Oregon vary from 1 to 1000 (ONHDB 2000). Monitoring studies have been conducted at several sites in Oregon, and show evidence of drastic declines in population sizes. Individuals that were grazed by cattle were weakened in the second year and absent in the third year. However, there was no control treatment, and so it cannot be concluded that livestock alone are responsible for the decline (DeBolt 1995). Micropropagation techniques using seeds and shoot-tip explant in culture has been explored by Edson (1998). Astragalus mulfordiae seedling establishment, adult survival and reproduction were studied at two populations between 1995 and 1997. The effects of re-vegetation (seeding) with Agropyron desertorum (or A. cristatum) and the impacts of cattle grazing on the demography of A. mulfordiae were observed. Using a visual estimate of grazing severity per plant, those plants in the seeded area that was exposed to cattle grazing were grazed more severely than the un-seeded area that had light horse grazing. Fruits per inflorescence, inflorescence per plant and adult plant survival were all significantly lower in the cattle-grazed area (David Pyke, personal communication).

  • 08/26/2020
  • Orthodox Seed Banking

Seed from 9 sites in Oregon and 4 in Idaho collected and stored at The Berry Botanic Garden.

  • 08/26/2020
  • Seed Collection

Seed from 9 sites in Oregon and 4 in Idaho collected and stored at The Berry Botanic Garden.

Nature Serve Biotics
  • 05/02/2017

Endemic to the western Snake River Plain in southwestern Idaho and adjacent Oregon. Several populations have been at least partially destroyed. There are only 34 known extant occurrences in Idaho and about half as many in Oregon. The majority of these populations are small in number of plants and in extent. Habitat destruction and degradation due to some combination of residential and agricultural development, sand mining, off-road vehicle activity, and livestock grazing has taken place in nearly all known populations.

Edward Guerrant, Ph.D.
  • 01/01/2010

General habitat degradation (DeBolt 2001). Urban expansion (DeBolt 2001). Livestock grazing and trampling (DeBolt 1995). Fires leading to cheatgrass (Bromus tectorum) invasion (DeBolt 1995). Off Road Vehicle (ORV) use (DeBolt 1995). Agricultura

Edward Guerrant, Ph.D.
  • 01/01/2010

As of 1995, 34 populations in Idaho, and 38 in Oregon. (DeBolt 1995) Population sizes in Oregon vary from 1 to 1000 (ONHDB 2000).

Edward Guerrant, Ph.D.
  • 01/01/2010

Monitoring studies have been conducted at several sites in Oregon, and show evidence of drastic declines in population sizes. Individuals that were grazed by cattle were weakened in the second year and absent in the third year. However, there was no control treatment, and so it cannot be concluded that livestock alone are responsible for the decline (DeBolt 1995). Micropropagation techniques using seeds and shoot-tip explant in culture has been explored by Edson (1998). Astragalus mulfordiae seedling establishment, adult survival and reproduction were studied at two populations between 1995 and 1997. The effects of re-vegetation (seeding) with Agropyron desertorum (or A. cristatum) and the impacts of cattle grazing on the demography of A. mulfordiae were observed. Using a visual estimate of grazing severity per plant, those plants in the seeded area that was exposed to cattle grazing were grazed more severely than the un-seeded area that had light horse grazing. Fruits per inflorescence, inflorescence per plant and adult plant survival were all significantly lower in the cattle-grazed area (David Pyke, personal communication). Germination trials at The Berry Botanic Garden indicate no specific requirements. Seeds were scarified and then subjected to cold stratification or no cold stratification and were then placed in germination chambers with constant 68F (20C) temperatures or alternating 50F/68F (10/20C) temperatures. Several treatments resulted in 100% germination (BBG File). Pollination studies (Idaho BLM) (DeBolt 2001).

Edward Guerrant, Ph.D.
  • 01/01/2010

Most populations on BLM land in Idaho are subject to springtime grazing (DeBolt 2001) Inventory of public lands in Idaho in the early to mid 1990's. Annual visit to many sites. Little formal monitoring (DeBolt 2001). Monitoring of burned and seeded sites on BLM land in Oregon. Seed from 9 sites in Oregon and 4 in Idaho collected and stored at The Berry Botanic Garden.

Edward Guerrant, Ph.D.
  • 01/01/2010

Determine pollination mechanism Study effect of grazing on population survival Study possible genetic differences between populations north and south of the Snake River (DeBolt 2001)

Edward Guerrant, Ph.D.
  • 01/01/2010

Collect and store seeds from across range. Determine propagation and reintroduction protocols.

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Photos
Nomenclature
Taxon Astragalus mulfordiae
Authority M.E. Jones
Family Fabaceae
CPC Number 450
ITIS 25594
USDA ASMU
Common Names Mulford's milkvetch | Mulford's milk-vetch
Associated Scientific Names Astragalus mulfordiae | Onix mulfordae
Distribution The """"Western Snake River Plain,"""" found in the Owyhee Uplands (Malheur Co.) of eastern Oregon and the Owyhee Front and Boise Foothills of western Idaho.
State Rank
State State Rank
Idaho S2
Oregon S1
Habitat

Found in shrub-steppe and desert shrub communities in the semi-arid, cold-desert region of southeast Oregon and southwest Idaho. The mean annual temperature is 50-52F (10-11C) with 8-13 inches (20-33cm) of precipitation. Plants are found on moderately steep to steep southeast, south, and southwest facing slopes consisting of old river deposits, sandy areas near rivers, sandy bluffs and dune-like talus. Elevations range from approximately 2,100 to 3,200 ft (640-975 m).

Ecological Relationships

Astragalus mulfordiae occurs within the western Snake River Plain, which has a semi-arid, cold-desert climate. Here it is found in deep lacustrine and alluvial deposits of relatively coarse substrates. Astragalus mulfordiae is associated with shrub-steppe and desert shrub communities, generally among Purshia tridentata and Stipa comata (antelope bitterbrush and needle and thread grass) (DeBolt 1995). Astragalus mulfordiae reproduces only by seed. The pollination mechanism unknown, but is most likely either flying insects or self-pollination. Seed is dispersed by gravity and wind as the stems and pods gradually weather away in the harsh winter conditions (DeBolt 1995).The weather patterns in late winter and early spring greatly influence timing of re-growth and phenological stages. In general, re-growth begins in early March, with flowering in April, May, and sometimes in to June. Fruit maturation is in June and July followed shortly by senescence (loss of leaves) (DeBolt 1995). Populations appear different in their abilities to withstand disturbances. Some sites have been extirpated through ORV use, cattle grazing and fire. However, there are some areas that are grazed in the spring where the plants have persisted. Some botanists have suggested that there may be a genetic difference between populations that are more susceptible or more tolerant of disturbances (DeBolt 2001).

Pollinators
Common Name Name in Text Association Type Source InteractionID
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting

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