CPC Plant Profile: Wyoming Tansy-mustard
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Plant Profile

Wyoming Tansy-mustard (Descurainia torulosa)

Description
  • Global Rank: G2 - Imperiled
  • Legal Status: N/A
  • Family: Brassicaceae
  • State: WY
  • Nature Serve ID: 156766
  • Date Inducted in National Collection: 02/09/1992

Descurainia torulosa is a small multi-stemmed biennial or short lived perennial in the mustard family. Tiny yellow flowers grow from the stems' tips and bloom in June. In late July the plant produces linear, hairy fruits, 8-15 mm long. (Atwood 1994). The tansy mustard does not seem to tolerate competition or excessive exposure to the sun or wind and grows under slight overhangs or in small cavities in volcanic rock. However, it has been found on fully exposed habitats such as small ledges (Marriott 1991). The remaining known populations are scattered and extremely small making this species quite vulnerable (Dorn, 1989). There is much confusion about the status of this species. Prior to 1990 there were only four sites reported for this species in the world, all in Wyoming. When visited in 1989, one population was not relocated and another was determined to be a separate taxon.

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Updates
  • 09/08/2020
  • Seed Collection

Additional seed collection needed.

  • 09/08/2020
  • Genetic Research

A limited taxonomic study has been done on this plant and members of the Descurainia genus, but further work is necessary (Marriott 1991).

Nature Serve Biotics
  • 05/02/2017

Known only from the high volcanic mountains of the Absaroka Range (northwest Wyoming) and isolated buttes in the Great Divide Basin (Pine Butte; Lions Bluff in southwest Wyoming). Thirteen small occurrences have been documented and much suitable habitat has not yet been searched. Populations tend to be very small in area and number of individuals and may fluctuate greatly from year to year. The species is largely protected from human disturbance by its rugged habitat, but is vulnerable to extinction due to intrinsic habitat instability and natural population fluctuations.

Thomas Grant
  • 01/01/2010

Threats include road building, drilling for oil and gas and natural disturbance such as rock fall and erosion (Marriott 1991).

Thomas Grant
  • 01/01/2010

Six populations known, but one is presumed to be a separate taxon. (Marriott 1992)

Thomas Grant
  • 01/01/2010

A limited taxonomic study has been done on this plant and members of the Descurainia genus, but further work is necessary (Marriott 1991).

Thomas Grant
  • 01/01/2010

Found on Forest Service and Bureau of Land Management lands that are managed. (Fertig 2000)

Thomas Grant
  • 01/01/2010

Taxonomic studies (lacking because of impoverished number of collections). Population monitoring is necessary.

Thomas Grant
  • 01/01/2010

Additional seed collection needed.

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Photos
Nomenclature
Taxon Descurainia torulosa
Authority Rollins
Family Brassicaceae
CPC Number 1395
ITIS 502006
USDA DETO2
Common Names Wyoming tansy-mustard | mountain tansymustard | Wind River tansymustard
Associated Scientific Names Descurainia torulosa
Distribution Endemic to the Absaroka Mountains and Rock Springs Uplift in Wyoming (Fremont, Park, Sweetwater, and Teton Cos.). (Marriott 1991, 1992)
State Rank
State State Rank
Wyoming S2
Habitat

This species is found growing on volcanic breccia, sandstone, and sparsely vegetated sandy slopes at base of N and NW facing cliffs at about 8,300-10,000 feet. This species has also been found in S to SW, E and N facing slopes, some growing under slight overhands, or in small cavities in the volcanic rock, others were in fully exposed habitat such as small ledges. (Marriott 1991)This species is associated with: Achillea millefolium (western yarrow), Erigeron compositus (cut-leaved daisy), and Oxyria digyna (mountain sorrel). (Dorn 1998)

Ecological Relationships

Ecological relationships are unknown.

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

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