Del Mar Manzanita [Arctostaphylos glandulosa Eastw. ssp. crassifolia (Jeps.) Wells]

Del Mar Manzanita [Arctostaphylos glandulosa Eastw. ssp. crassifolia (Jeps.) Wells]

Listing CNPS List 1B R-E-D Code 3-3-2

State/Federal. Status -- /PE ERICACEAE Dec.-Apr.

Global Rank G5T1 State Rank S1.1

Distribution: Coastal San Diego County; Baja California, Mexico

Habitat: Del Mar Manzanita occurs in chaparral with Adenostoma fasciculatum and often Ceanothus verrucosus. Typically, the substrate is eroding sandstone, and the chaparral vegetation is relatively low-growing. Soils include Terrace Escarpments and Loamy alluvial land of the Huerhuero complex.

Known Sites: This manzanita grows in both northern and southern extensions of the Torrey Pines State Preserve. It is occasional in Lomas Santa Fe such as in San Dieguito County Park, near Del Mar Heights Road and Dunham Way, in Encinitas near Whisper Wind Lane, east of El Nido Road in Rancho Santa Fe, at Oak Crest Park in Encinitas, west of Ivy Glen Drive in Encinitas, as well as south of Encinitas Creek and east of El Camino Real. Several hundred shrubs grow south of Del Mar Heights Road and east of El Camino Real in a vestigial stand of chaparral not yet developed. Herbarium specimens at SD are for the bluffs south of Del Mar Heights School, on the west side of Lux Canyon in Cardiff, 0.8 km west southwest of Alga Road southeast of Carlsbad, south of Encinitas Boulevard and west of Manchester Avenue in Encinitas, and 0.1 km east of El Camino Real and 0.6 km south of Palomar Airport. Reports are from a canyon drainage on the western slopes of Carmel Mountain, and east of Rancho Santa Fe Road near Avenida La Posta. Old biological survey reports note sites northeast and east and southeast of Miramar Lake (unconfirmed and well east of the typical range; this site needs to be compared with the more common var. zacaensis), on the northern slopes of La Zanja Canyon, north of Willow Spring Drive in Olivenhain, between La Glorieta and Rambla de las Flores in Rancho Santa Fe, west of the Olivenhain Cemetery, by Mountain View Road and El Camino Real in Encinitas, at Oak Crest Park in Encinitas, the northwest end of Green Valley in Encinitas, near Circo Diegueno Road east of Del Mar, the Crest Canyon drainage in Del Mar, El Apajo Road just south and beyond the Rancho San Dieguito boundary, 1 mile north of Batiquitos Lagoon and 0.5 mile west of El Camino Real. One unconfirmed report is well to the north of concentrated populations at Fire Mountain in Oceanside; reports from near Mount Whitney and Del Dios need to be verified as not the more common var. zacaensis. Data Base Reports are from northeast of Palomar Airport Road near the El Camino Real Intersection, west of Letterbox Canyon and north of Palomar Airport, scattered along both sides of El Camino Real from Batiquitos Lagoon to Palomar Airport, 1 km north of Batiquitos Lagoon and 1.5 km west of El Camino Real, 0.5 km south of Encinitas Creek and 0.7 km east of Manchester Avenue, at Eden Gardens in Solana Beach 0.8 km northwest of Interstate 5 near the Via de la Valle intersection, south of the San Dieguito River and 1 km south of Via De la Valle on the southeast side of El Camino Real, 0.3 km southwest of mouth of Shaw Valley in Carmel Valley.

Five herbarium specimens (annotated by Wells) from Baja California are found at the San Diego Natural History Museum; south to 32 degrees 10 1/2 minutes North where collected by Moran on the western edge of Mesa de Descanso, east of Medio Camino (SD 110476). It is also recorded on the north slope of the southern peak of Cerro Jesus Maria, on a ridge 4 miles east of Cerro Coronel, and as abundant on Cerro del Coronel.

Status: This substantial shrub is slowly declining in San Diego County as infilling occurs in residential areas from Torrey Pines and Del Mar north to Encinitas. Primary impacts are due to urban expansion. All of the larger, relatively intact populations (i.e., not already fragmented by piecemeal development) are recommended for protection. Isolated, individual shrubs should be placed into biological open space whenever possible.

Copyright May 1994 Craig H. Reiser.

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