Layne's Butterweed
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Sacramento Fish & Wildlife Office
Species Account
LAYNE'S BUTTERWEED
(Senecio layneae)
CLASSIFICATION: Federal Threatened Species (Federal Register 61:54346 pdf; October 18, 1996)
CRITICAL HABITAT: None designated.
RECOVERY PLAN: Recovery Plan for Gabbro Soil Plants of the Central Sierra Foothills. 2002
DESCRIPTION:
Layne's butterweed (Senecio layneae), also known as Layne's ragwort, is a perennial herb of the aster family (Asteraceae). The plant sprouts from a rootstock. Its mostly basal lance-shaped leaves are 3 to 10 inches long.
Flowers appear between April and June. The several flower heads are 2 to 3 inches wide, each having five to eight orange-yellow ray flowers and many yellow disk flowers. See Hickman (1993) in General Information about California Plants, below, for a detailed description of the species, as Layne's ragwort.
DISTRIBUTION:
Layne's butterweed grows in open rocky areas of gabbro and serpentine soils within chaparral plant communities. Most known sites are scattered within a 40,000 acre area in western El Dorado County that includes the Pine Hill intrusion and adjacent serpentine. A few other colonies occur in the Eldorado National Forest in El Dorado County, in the Bureau of Land Management (BLM) Red Hills Management Area in Tuolumne County, and on BLM land in Yuba County. However, most colonies are on privately owned land. One site is on land managed by the California Department of Forestry and the California Department of Fish and Game.
Gabbro soils originate from volcanic rocks (gabbrodiorite) that are mildly acidic, are rich in iron and magnesium, and often contain other heavy metals such as chromium. Gabbro, a dark large-crystalled rock, is formed when liquid magma cools slowly underground. A red soil is formed when the rock is exposed and weathers at the earth's surface. These soils are well-drained and are underlain by gabbrodiorite rocks at a depth of more than 3 feet.
Serpentine-derived soils are formed through a process similar to formation of gabbro soils. Serpentine soils are derived from serpentinite, dunite, and peridotite. They tend to have high concentrations of magnesium, chromium, and nickel, and low concentrations of calcium, nitrogen, potassium, and phosphorus. Most plants do not grow well on gabbro or serpentine soils.
SPECIAL CONSIDERATIONS:
Residential and commercial development, road maintenance, change in fire frequency, off-road vehicle use, competition with nonnative vegetation, excessive horse paddocking, mining, and other human-caused conditions variously threaten and are responsible for the declining trend for Layne's butterweed.
The species was listed as rare by the California Department of Fish and Game in November 1979 under the name Layne's ragwort. The California Native Plant Society has placed it on List 1B (rare or endangered throughout its range), also as ragwort.
Learn more about protection efforts by the Pine Hill Preserve.
REFERENCES FOR ADDITIONAL INFORMATION:
Kruckeberg, A. 1984. California Serpentines: Flora, Vegetation, Geology, and Management Problems. Berkeley, CA: University of California Press.
U.S. Fish & Wildlife Service. 1996. Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Four Plants and Threatened Status for One Plant From the Central Sierran Foothills of California. Portland, Oregon.
U.S. Fish and Wildlife Service. 2002. Recovery Plan for Gabbro Soil Plants of the Central Sierra Nevada Foothills. Portland, Oregon.
Wilson, J. L. 1986. A study of plant species diversity and vegetation pattern associated with the Pine Hill gabbro formation and adjacent substrata, El Dorado County, California. Sacramento, CA: California State University, Sacramento. Thesis.
General Information about California Plants
Photo credit: Layne's butterweed by Harry Mossman, U.S. Fish & Wildlife Service
Prepared by Endangered
Species Div., Sacramento Fish & Wildlife
Office, U.S. Fish & Wildlife
Service
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