Pine Hill Flannelbush

Fremontodendron californicum ssp. decumbens

Description

Pine Hill flannelbush, Fremontodendron californicum ssp. decumbens is a branched spreading shrub of the cacao family (Sterculiaceae) growing to 4 ft (120 cm) tall. Dense star-shaped hairs cover the leaves and the younger twigs and branchlets. The leaves of the subspecies are elliptic-ovate to ovate, shallowly or deeply palmately lobed with 5 to 7 lobes. Showy light-orange to reddish-brown flowers appear from late April to early July. Its fruit is a capsule. Fremontodendron californicum ssp. decumbens can be distinguished from F. californicum ssp. californicum and F. mexicanum by its decumbent growth habit, its relatively long peduncles, and its copper-orange flowers.

Beecher Crampton made the first collection of Fremontodendron californicum ssp. decumbens in 1956. Nine years later, Robert Lloyd described F. californicum ssp. decumbens as F. decumbens based on the type specimen Lloyd collected in May 1964 from "California, El Dorado Co., Pine Hill, ca. 3 km north of Rescue." Philip Munz reduced F. decumbens to a subspecies of F. californicum in 1968. Walter Kelman, in his 1991 revision of Fremontodendron, recognizedF. californicum ssp. decumbens as a full species based upon morphological variation. Nonetheless, the plant is treated as F. californicum ssp. decumbens in the Jepson Manual.

Habitat

Pine Hill flannelbush occurs on scattered rocky outcrops either in fire-dependent chaparral or in the ecotone between woodland and chaparral. This taxon also appears in the ecotone between chaparral and oak woodland. The subspecies depends on fire to promote seed germination, and it was documented that seeds are dispersed by ants in 1996.

Distribution

It is only known from one localized area near Pine Hill in western El Dorado County scattered within an area of approximately 5,000 acres (2,000 hectares). Although there are some reports of Pine Hill flannelbush occurring in some small scattered populations in Yuba or Nevada County, other reports describe these individuals as aberrant F. californicum ssp. californicum. Pine Hill flannelbush occurs primarily on private land, but one site is on Bureau of Land Management land. The California Department of Forestry and the California Department of Fish and Game also own another site. The largest population of Pine Hill flannelbush is on the Pine Hill Ecological Reserve managed by CDFG.

Threats

The proximity of this plant to human population centers and intensive development activities renders Pine Hill flannelbush vulnerable to the long-term effects of fire suppression. The restricted distribution of the subspecies increases its susceptibility to catastrophic events such as disease or pest outbreak, severe drought, or other natural or human-caused disasters. In addition, residential and commercial development, including unregulated grading for homes or barns on existing large parcels, and trash dumping threaten this taxon.

Construction of houses on and near Pine Hill resulted in the loss of many individuals of Pine Hill flannelbush. Land clearing activities that occur with road construction also threaten this plant. In 1968, all the vegetation along the Pine Hill approach road was cut. The west slope of Pine Hill was cleared by the CDF in 1969, demolishing 80% of the Pine Hill flannelbush within the boundaries of the current Pine Hill Ecological Reserve. Most of these shrubs have resprouted. The Pine Hill Ecological Reserve, managed by CDFG, presently has the largest occurrence of this taxon.

Disease is a potential threat for Pine Hill flannelbush. In cultivation, this taxon is highly susceptible to a wilt disease that can kill the plant almost overnight. This mortality has not been observed in the field. Plants proximate to residences may be vulnerable to supplemental moisture from irrigation of lawns or gardens.

Intense insect and rodent predation occurs on Pine Hill flannelbush. Reproductive attrition in this taxon was studied, and it was found that less than 2% of flower buds produced fruit because of predation by insects. In addition, rodents destroyed 90% of seeds under shrubs within 8 to 10 months. Because Pine Hill flannelbush is very restricted in range and few individuals exist, this predation increases the chance for stochastic extinction.

Excessive fire frequency also potentially threatens Pine Hill flannelbush. This plant needs sufficient time between burns to set enough seed to replenish the soil seedbank. Mature plants of this taxon also need to build up carbohydrate reserves to be able to resprout after a fire. Pine Hill flannel-bush seeds require heat from fire to germinate. This taxon also resprouts vegetatively after a burn. In a 1992 study of reproductive attrition in Pine Hill flannelbush, it was found that seeds of this plant cannot successfully develop and germinate without the benefit of fire. The study concluded that to maintain genetic diversity and establish plants at new localities within the boundaries of the current populations, sexual reproduction versus plant root sprouting may be necessary over long time periods. These goals could be accomplished by controlled burns.

Habitat degradation from garbage dumping on ridge-tops around Pine Hill is a minor threat to this plant.

Pine Hill flannelbush has been used horticulturally, but does not appear to be threatened by collection in the wild.

Conservation and Recovery

The Pine Hill flannelbush is restricted to scattered populations in one localized area. One critical habitat is in the Pine Hill Ecological Reserve owned by the CDFG, and is being kept in a natural condition. Other populations are on land owned by the Federal Bureau of Land Management and the CDF. These government-owned habitats must be protected against any threatening activities, and this action should be reflected in the management plans for these public lands. All other critical habitats are on privately owned lands. The best critical habitats on private land should be identified and protected. This could be done by acquiring the land and designating ecological reserves, or by negotiating conservation easements with the landowners. The habitat will have to be managed to maintain its suitability for the Pine Hill flannelbush, possibly by the use of prescribed burns. The populations of the rare plant must be monitored, and research undertaken into its basic biology and ecological requirements, particularly with regard to fire ecology.

Contact

U.S. Fish and Wildlife
Service Sacramento Fish and Wildlife Office
Federal Building
2800 Cottage Way, Room W-2605
Sacramento, California 95825-1846
Telephone: (916) 414-6600
Fax: (916) 480-4619

Reference

U.S. Fish and Wildlife Service. 18 October 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." Federal Register 61 (203): 54346-54358.