Heliotrope Milk-vetch

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Heliotrope Milk-vetch

Astragalus montii

Status Threatened
Listed November 6, 1987
Family Leguminosae (Fabaceae)
Description Perennial herb with tiny compound leaves and pink-purple flowers.
Habitat Limestone outcrops.
Threats Mineral exploration, grazing animals.
Range Utah

Description

Heliotrope milk-vetch, Astragalus montii, is a perennial herbaceous plant in the legume family, with tiny compound leaves and two to eight pinkish purple white-tipped flowers. The fruit is a mottled, inflated pod. The species is very low-growing, nearly stemless plant approximately 0.4-2 in (1-5 cm) tall.

A. limnocharis var. montii is a synonym for heliotrope milk-vetch.

Habitat

Heliotrope milk-vetch is restricted to outcrops of limestone barrens near the timberline of the Wasatch Plateau in the Utah Plateau section of the Intermountain region. In this region some 40 endemic plant species occur as related pairs, such as the rare and northerly A. montii and its somewhat more plentiful and southern counterpart, A. limnocharis.

The elevation of this region is generally from 4921-8,858 ft (1,500-2,700 m). These strongly sloping to precipitous mountains have narrow crests and valleys. Some high plateaus have gently sloping tops and steep sides, and the mountains are dissected by numerous streams.

Distribution

Heliotrope milk-vetch, endemic to the Wasatch Plateau, has long been rare, and has a very limited distribution. It is known from three populations in the Heliotrope Mountain in Sanpete County, Utah, and White Mountain in Sevier County, Utah. In 1985, about 2,500 plants were known to grow on the western portion of Heliotrope Mountain. This population, spread over 60 acres (24 hectares), is divided between two colonies less than a mile apart, separated by the mountain crest.

A second population of about 4,000 plants, discovered in 1983, grows on 37 acres (15 hectares) of Heliotrope Mountain, near where it joins Ferron Mountain. A third population, also of some 4,000 plants discovered in the mid 1980s, occurs about 6 mi (9.7 km) south of Heliotrope Mountain on White Mountain in Sevier County. No other populations have been located; but within a decade, the known populations had increased significantly: In 1995, the combined estimates of the three known populations stood at approximately 200,000 individuals, occupying a total area of about 400 acres (161.9 hectares).

Threats

The Heliotrope milk-vetch was listed as Endangered due to its limited habitat and small population size, and to current and potential threats from grazing and oil and gas surface disturbing activities to the species habitat. The general area of the Heliotrope and White Mountains is an active oil and gas exploration region, associated with the over-thrust belt of the western United States. Oil and gas exploration could eventually threaten this species. Leases for the area, as issued by the Bureau of Land Management, stipulate that Endangered and Threatened species be protected during any exploration activity.

Conservation and Recovery

Critical Habitat has been designated to include the population on Heliotrope Mountain in Sanpete County, Utah. Because there is little horticultural or scientific interest in this species, the Wildlife Service felt that publicizing Critical Habitat boundaries would not create undue collection interest.

The plant's Recovery Plan, announced in draft form in 1995, has the stated goal of maintaining viable populations of the species at its known sites to ensure the species survival, and guiding recovery efforts to facilitate delisting of the species. Recovery efforts will focus on protecting the species population and habitat from habitat destroying activities. The plan also calls for biological and ecological research of the species' biology and its relationship and interaction with its environment to guide future management of the species population and habitat to ensure its continued survival and the preservation of the species ecosystem. Additional recovery efforts will focus on inventory of potential habitat and minimum viable population studies of its known populations.

Contact

Regional Office of Endangered Species
U.S. Fish and Wildlife Service
P.O. Box 25486
Denver Federal Center
Denver, Colorado 80225
http://www.r6.fws.gov/

References

Cronquist, A., A. H. Holmgren, N. H. Holmgren, and J. L. Reveal. 1972. Intermountain Flora. Hafner Publishing Company, New York.

Thompson, R. 1980. "Status Report on Astragalus montii." U.S. Forest Service, Manti-LaSal National Forest, Utah.

Welsh, S. L. 1978. "Endangered and Threatened Plants of Utah: A Reevaluation." Great Basin Naturalist 38:1-18.

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