Overview
Layne鈥檚 butterweed is an early successional perennial herb of the aster family with orange-yellow flowers that is found at Pine Hill Preserve and in five general areas: two locations near Brownsville in Yuba County; Sugarpine Reservoir and Michigan Bluff on Tahoe National Forest in Placer County; Little Bald Mountain and along Traverse Creek near Georgetown on El Dorado National Forest in El Dorado County; scattered private lands in El Dorado County outside the Pine Hill Preserve; and roughly six locations near Don Pedro Reservoir in Tuolumne County. The Layne鈥檚 butterweed populations in Yuba and Placer counties and two of the six Tuolumne County populations have been newly discovered since listing.
The primary threat to Layne鈥檚 butterweed is the encroachment of native vegetation due to succession, even on lands in conservation ownership, in the absence of the natural fire regime. The long fire return interval due to fire suppression is preventing the formation of necessary clearings for Layne鈥檚 butterweed establishment and possibly the scarification of seeds needed for their germination. Other threats include invasive plants and development and habitat fragmentation. Invasive species including yellow starthistle (Centaurea solstitalis) and distaff thistle (Carthamus lanatus) have threatened a population within the Bureau of Land Management Red Hills Kanaka Point Property in Tuolumne County. Threats from fire suppression activities, off-road vehicle use and mining activities affect Layne鈥檚 butterweed on Tahoe and Eldorado National Forests.
Layne鈥檚 butterweed was listed as threatened on October 18, 1996.
Characteristics
Physical Characteristics
Layne鈥檚 butterweed is a perennial herb of the aster family that sprouts from a rootstock. Leaves are mostly basal lance-shaped and are 3 to 10 inches long. Each flower head has 5 to 8 orange-yellow petal-like ray flowers and numerous yellow disk flowers. The flower heads are 2 to 3 inches wide.
Habitat
Layne鈥檚 butterweed grows in open rocky and disturbed areas within chaparral plant communities, primarily on gabbro soil formations and occasionally on serpentine soils. At Traverse Creek on the Eldorado National Forest, Layne鈥檚 butterweed occurs on serpentine soil within chaparral associated with buckbrush, blue oak and foothill pine. In other parts of the National Forest, Layne鈥檚 butterweed is also associated with California bay.
Life Cycle
Layne鈥檚 butterweed flowers from April to July. Observations suggest that it鈥檚 an early successional species that occupies temporary openings on gabbro or serpentine soils and is eliminated as vegetation grows up around it. The predominant breeding system for Layne鈥檚 butterweed is likely outcrossing pollination. It is unclear whether the species has the ability to resprout from its caudex after disturbance. Although the seed of this species seems to germinate in a wide range of soil conditions and adult plants grow in a wide range of slope, aspect, light and elevation levels, it appears to have little or no persistent seedbank, a short seed dispersal distance, and is also shade intolerant.