White Coast Ceanothus [Ceanothus verrucosus Nutt. in T. & G.]
Listing CNPS List 2 R-E-D Code 1-2-1
State/Federal. Status -- /C2 RHAMNACEAE Jan.-Apr.
Global Rank G2? State Rank S2
Distribution: San Diego County; Baja California, Mexico
Habitat: Coastal Chaparral intermixed with Chamise and Mission Manzanita is the preferred habitat for this sizeable shrub. Typically, the White Coast Ceanothus is a dominant shrub within the vegetation community where it occurs. It may be particularly vigorous on north-facing slopes, but can accommodate more xeric aspects. Exchequer rocky silt loams and San Miguel-Exchequer rocky silt loams are utilized by the dense populations of this ceanothus in the Mount Whitney (San Diego County) area. Terrace Escarpments are the soil type mapped beneath this shrub at Torrey Pines, while Gaviota fine sand loams are found at the Point Loma populations.
Known Sites: Sizeable populations are found on the Point Loma Subase, at Carmel Mountain, on north-facing slopes near the Miramar Landfill in San Clemente Canyon, and on the north-facing slopes of Escondido Creek 1 mile east of Lake Val Sereno. Another substantial population grows at Torrey Pines. A small population is still extant on an urban hillside in East San Diego, indicating that sizeable tracts of urban lands may once have been cloaked in White Coast Ceanothus. This shrub is the dominant plant in rugged terrain south of Mount Whitney. Here and surrounding the nearby Questhaven Retreat it occurs in the tens of thousands. It is also common at the crest of the road to Mount Israel on Rancho Cielo; as well as in the hills to the north. Once regionally abundant within the coastal canyons of the county, Ceanothus verrucosus has been substantially reduced in numbers because of urban sprawl. Other locales where this shrub is found include near Rossini Drive in Cardiff, north of the terminus of Swallowtail Road in Encinitas, near Del Mar Heights Road and Dunham Road, south of Del Mar Heights Road and east of El Camino Real, in La Zanja Canyon, north of Woodwind Drive in Olivenhain, on Carmel Mountain, and well distributed in the canyons between the Miramar landfill and the Interstate 805. Numerous other locales between La Jolla and Carlsbad could be identified. Old biological survey reports are from between La Glorietta and Rambla de las Flores in Rancho Santa Fe, southwest of Sienna Canyon Drive in Encinitas, south of Avenida del Diablo in western Escondido, near the intersection of Fairmont and Montezuma Road in the vicinity of San Diego State University, in San Elijo Canyon southwest of Harmony Grove, in the Crest Canyon drainage in Del Mar, near El Apajo Road just south and beyond the Rancho San Dieguito boundary, 0.5 mile northeast of Lake Hodges, at Fairbanks Ranch 0.5 mile north of La Zanja Canyon and 1 mile east of San Dieguito Valley, near Quail Gardens in Encinitas, and east of Interstate 5 and south of Palomar Airport Road.
Twenty-seven collections from Baja California are found at the San Diego Herbarium; south to 28 21' North where collected by Moran (SD 78000) on Cedros Island. It is locally common in coastal chaparral north of Ensenada, Mexico; occasional on Punta Banda Peak.
Status: Several very vigorous populations of White Coast Ceanothus are extant; however, it is declining locally on the periphery of the coastal cities in San Diego County. It is recommended that protection focus on several massive populations in the Mount Whitney and Mount Israel areas.
Copyright © May 1994 Craig H. Reiser.
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