San Mateo Woolly Sunflower

Eriophyllum latilobum

Description

The San Mateo woolly sunflower, Eriophyllum latilobum, is an herbaceous perennial of the aster family (Compositae or Asteraceae) with leafy stems 12-16 in (30.5-40.6 cm) high. The upper surfaces of the deeply cleft leaves are a smooth dark green and the lower surfaces are covered with densely interwoven white hairs. The golden flower heads are borne in loose clusters.

E. latilobum differs from E. confertiflorum, golden yarrow, in having seven to eight ray flowers rather than five ray flowers, and a more open inflorescence. E. lanatum var. arachnoideum, common woolly sunflower, differs from the other two species in having 13 ray flowers and shallowly cleft leaves. San Mateo woolly sunflower can be mistaken for plants from several populations that seem to be of hybrid origin between E. lanatum and E. confertiflorum. Plants of these populations have either four or six sets of chromosomes and are located near Black Mountain and Montebello Ridge.

San Mateo woolly sunflower is an herbaceous perennial that flowers from April to June. Its pollinators include syrphid flies and bees. Although the species grows side-by-side with one of its presumed progenitors, E. confertiflorum, no intermediate plants have been found to suggest that ongoing hybridization is occurring. Because seed dispersal is by gravity, most seeds fall close to the parent plant. Germination rates for San Mateo woolly sunflower appear to be lower than those of other species of the same genus and other related species. The species is difficult to grow in the greenhouse because of its susceptibility to white flies.

Habitat

San Mateo woolly sunflower is found in shaded moist sites on steep grassy or sparsely wooded slopes, apparently growing best under or very near coast live oak. The species has been reported on serpentine soils and, in some cases, on soils not considered serpentine. The single remaining population occurs at an elevation of 150 ft (45.7 m). The federally listed threatened Marin dwarf-flax reportedly grows in association with San Mateo woolly sunflower.

Distribution

The single remaining population of San Mateo woolly sunflower consists of a few hundred plants scattered along 2.5 mi (4 km) of Crystal Springs Road in San Mateo County. The plants are distributed in less than a dozen small subpopulations from the Eugene A. Doran Bridges to just south of the intersection of Crystal Springs Road and Memer Road. These subpopulations are probably the fragments of a once-continuous population. San Mateo woolly sunflower has also been reported from southern San Mateo County, on Pescadero Road southwest of La Honda, but this report is most likely erroneous.

The remaining population contained 315 plants in 1992, about 60 in 1993, and 163 in 1994. Some years the number of plants in some subpopulations ranges from zero to less than five; other years the same subpopulations contain 500% more plants. Some subpopulations consistently have higher numbers of plants. According to Roman Gankin, especially large numbers were observed in 1996. Gankin observed 100 or more plants scattered throughout the north-facing cliff area along Crystal Springs Road, approximately 328 ft (100 m) east of the junction of Polhemus and Crystal Springs Roads.

Threats

The single remaining population consists of a few hundred plants that occur along 2.5 mi (4 km) of Crystal Springs Road in San Mateo County. Seventy-five percent of the plants occur within 30 ft (9.1 m) of the road. The city of Hillsborough, the San Mateo county, and the San Francisco Water Department have varying jurisdictions over the land. San Mateo woolly sunflower is threatened by erosion and soil slippage, recreational development, road maintenance, and garbage dumping.

The steep slopes along Crystal Springs Road provide a very risky habitat for San Mateo woolly sunflower. The slopes are subject to erosion and soil slippage. After soil slippage occurs, the slumped soil, which may contain mature individuals, seedlings, and/or seeds, is removed by road maintenance crews. The road cut is then reshaped, which may damage plants remaining on the banks. Slide repair work in 1997 took place along Polhemus Road, but did not impact the San Mateo woolly sunflower population.

The San Francisco Water Department has a recreational easement through the population. The proposed construction of the San Mateo Creek Trail, part of the San Mateo County Trails Plan, would have adverse impacts on the plant if trail design does not incorporate plant conservation. The paved trail, which is 10 ft (3 m) wide, is expected to run adjacent to Crystal Springs Road from Skyline Boulevard to the San Mateo City boundary. Construction of the trail could damage or eliminate colonies of San Mateo woolly sunflower, alter site hydrology, accelerate soil erosion through increased pedestrian and bicycle traffic, and allow for the introduction of aggressive non-native plant species. However, according to Sam Hertzberg of the San Mateo County Planning Department, the trail is unlikely to be constructed in the near future.

Road maintenance also threatens San Mateo woolly sunflower. Threats include reshaping of the slope and periodic mowing to reduce fuel loads. Mowing by San Mateo County is probably the main threat to the species at sites outside the Hillsborough City limits. San Mateo County road maintenance crews were alerted to the existence of San Mateo woolly sunflower in 1990 and were instructed by the San Mateo County Planning Department to avoid the plants; however, road maintenance activities are not monitored to ensure protection. The San Mateo County Department of Public Works has eliminated the use of weed sprays along the section of road where the species occurs.

Dumping of garden debris and downhill seepage of herbicides and insecticides from homeowners living above the population may have negative impacts on San Mateo woolly sunflower habitat. The plant also is threatened by competition with non-native plants; its habitat is more densely populated with plumeless thistle and brome than it was 10 years ago.

Unrestricted collecting for scientific or horticultural purposes, or excessive visits by individuals interested in seeing rare plants could be a threat to the species. San Mateo woolly sunflower, with its showy golden flowers and proximity to roads and the proposed San Mateo Creek Trail, might prove to be especially tempting to collectors.

San Mateo woolly sunflower is not a vigorous reproducer; low germination rates and low seedling survival have been observed under greenhouse conditions. In the natural population, competing species such as plumeless thistle may affect germination and seedling establishment. Beetle larvae have been observed in seed heads of San Mateo woolly sunflower; however, the extent of predation is unknown. Because of the existence of only a single population exhibiting low viability and located in an unstable habitat, this species is extremely vulnerable to extinction from random catastrophic events.

Conservation and Recovery

Roadside mowing by San Mateo County in the vicinity of San Mateo woolly sunflower has been stopped, and the use of weed sprays has been eliminated by the San Mateo County Department of Public Works along the section of road where the species occurs.

Contact

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

Reference

U.S. Fish and Wildlife Service. 1998. "Recovery Plan for Serpentine Soil Species of the San Francisco Bay Area." Portland, Oregon, 330+ pp.