San Mateo woolly sunflower is a California endangered plant species, which means that killing or possessing plants is prohibited by the California Endangered Species Act (CESA). The species is also listed as endangered under the federal Endangered Species Act. San Mateo woolly sunflower is a 12- to 16-inch tall herbaceous perennial of the sunflower family (Asteraceae) that has deeply cleft leaves consisting of an upper surface that is smooth and dark green and a lower surface that is covered with densely interwoven white hairs. The gold-colored loose clusters of flower heads typically bloom from April to June. San Mateo woolly sunflower is found in moist shady locations on sparsely wooded or steep grassy slopes in San Mateo County. At the time of this webpage posting, the California Natural Diversity Database reported 3 natural occurrences of the species that are presumed to still exist.
The historical distribution of San Mateo woolly sunflower is unknown, but it is thought to be of hybrid origin from E. lanatum var. arachnoideum and E. confertiflorum. At the time of listing (1995) the greatest threat to San Mateo woolly sunflower was destruction of habitat through urban development, road maintenance and trail construction. San Mateo County Department of Public Works has eliminated the use of weed sprays and roadside mowing in the vicinity where the San Mateo woolly sunflower is known to occur. Conservation efforts are being made to protect the species and its habitat through control of non-native invasive species on San Francisco Public Utilities Commission property.
Other threats to San Mateo woolly sunflower include dumping of garden debris, downhill seepage of pesticides from homeowners living above some populations, dependency on rare soil types, competition with non-native plants, low germination rates, low seedling survival, limited ability for seed dispersal, and small population size, which makes this species extremely vulnerable to extinction from random catastrophic events. Impacts to this species as a result of climate change are unclear. Because San Mateo woolly sunflower is dependent on a rare soil type and has a limited ability for seed dispersal, climate change may pose a significant threat to the species in the future.
CDFW may issue permits for San Mateo woolly sunflower pursuant to CESA, and you can learn more about the California laws protecting San Mateo woolly sunflower and other California native plants. Populations of San Mateo woolly sunflower occur in CDFW’s Bay Delta Region. More information is also available from the U.S. Fish and Wildlife Service Species Profile for San Mateo woolly sunflower.