Pine Hill Ceanothus
Pine Hill Ceanothus
|Listed||October 18, 1996|
|Description||Prostrate evergreen shrub with smooth gray-brown branches and small white flowers tinged with blue.|
|Habitat||Fire-dependent chaparral habitat.|
|Threats||Residential and commercial development, off-road vehicle use, road-widening, change in fire frequency.|
Pine Hill ceanothus, Ceanothus roderickii, is a prostrate evergreen shrub of the buckthorn family (Rhamnaceae) that generally grows to 9.8 ft (294 cm) in diameter. The smooth gray-brown branches radiate from a central axis and root when they come into contact with the ground. The leaves of the species are semi-erect with entire margins. Small whitish flowers tinged with blue appear from May through June. Its fruit is an inconspicuously horned globe-shaped capsule.
Beecher Crampton first collected Pine Hill ceanothus in 1956 from Pine Hill in El Dorado County, California. Walter Knight described C. roderickii in 1968, naming it after Wayne Roderick, who first suspected the horticultural value of this endemic shrub. Knight considered C. roderickii to be most closely related to C. cuneatus, which also grows throughout the area. Pine Hill ceanothus can be differentiated from its congeners by its blue-tinged flowers, prostrate habit, and inconspicuously horned fruit.
Pine Hill ceanothus is restricted to gabbro-derived soil in openings in chaparral or more infrequently on previously disturbed sites within chaparral. Pine Hill ceanothus occurs in fire-dependent chaparral habitat.
The species is restricted to one localized area of approximately ten known extant occurrences discontinuously scattered in the Pine Hill intrusion. Pine Hill ceanothus occurs primarily on private land. The Bureau of Land Management owns part of one site and the California Department of Forestry owns another site.
Residential and commercial development, inadequate regulatory mechanisms, off-road vehicle use, road-widening, change in fire frequency, and other human-caused conditions are responsible for the decline of C. roderickii. Commercial development has extirpated two known occurrences.
Shopping center construction and other commercial development extirpated two occurrences of Pine Hill ceanothus. Road-widening also threatens the habitat of C. roderickii at one site. Off-road vehicle use degrades the habitat at three sites in the northern part of the area.
Excessive fire frequency also potentially threatens Pine Hill ceanothus. 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. In a study conducted in 1985 and 1987 of the effects of controlled burning on three rare plants occurring on Pine Hill within western El Dorado County, it was discovered that fire killed C. roderickii shrubs, but caused a twenty-two-fold increase in seed germination and that the growth rate of seedlings was greater in the burned area than in the unburned area.
Herbicide spraying and trash dumping threaten one occurrence of Pine Hill ceanothus. Pine Hill ceanothus has been used horticulturally, but it does not appear to be threatened by collection in the wild.
Conservation and Recovery
The Pine Hill ceanothus is restricted to only about ten populations in one localized area. One critical habitat is owned by the federal Bureau of Land Management, and another by the California Department of Forestry. These habitats must be strictly 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 ceanothus, 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 regards to fire ecology.
U.S. Fish and Wildlife Service
Sacramento Fish and Wildlife Office
2800 Cottage Way, Room W-2605
Sacramento, California 95825-1846
Telephone (916) 414-6600
Fax: (916) 480-4619
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.