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Plant Profile

Del Mar Manzanita (Arctostaphylos glandulosa ssp. crassifolia)

Global Rank: T2 - Imperiled
Legal Status: Federally Endangered
Family: Ericaceae
State: CA
Nature Serve ID: 134136
Lifeform: Shrub
Date Inducted in National Collection:

Description:

The Del Mar manzanita is the rarest of the six recognized subspecies of Eastwood Manzanita, Arctostaphylos glandulosa. The Del Mar or Costa Baja manzanita, is a small to medium sized evergreen shrub with thick leathery leaves and clusters of dainty urn-shaped white to pink flowers in late winter to early spring (NatureServe 2016). This manzanita species, like its many other relatives endemic to California, is an important member of the chaparral plant community. It can survive long periods of drought and periodic fires by crown-sprouting from a well developed basal burl (USFWS 2010). Like other manzanitas the flowers are an important source of nectar for insect and hummingbird species while the fruits serve as an important food source for mammals that live in the region where the plants occur.

Where is Del Mar Manzanita (Arctostaphylos glandulosa ssp. crassifolia) located in the wild?

Habitat:

The Del Mar manzanita is only found on coastal bluffs on sandstone substrates in San Diego County and northern Baja California. They grow only within the rare and threatened maritime chaparral plant community. Due to extensive urban expansion, through a good portion of this species range, many former substantial populations have since been severely fragmented and exist only as isolated individuals on remnant city parcels. Some of the best populations exist and are protected at Torrey Pines State Reserve (USFWS 2010.

Distribution:

This endangered taxon is endemic to the southcentral coast of San Diego County south into extreme northwestern Baja California, Mexico (40 km south of the U.S.-Mexico border) (USFWS 2010).

States & Provinces:

Del Mar Manzanita can be found in California

Which CPC Partners conserve Del Mar Manzanita (Arctostaphylos glandulosa ssp. crassifolia)?

California Botanic Garden

Not Sponsored

Assigned 06/09/17

San Diego Botanic Garden

Not Sponsored

Assigned 12/29/17

University of California-Santa Cruz Arboretum & Botanic Garden

Not Sponsored

Assigned 01/17/19

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

Nature Serve Biotics

05/02/2017

Endemic to the southcentral coast of San Diego County south into extreme northwestern Baja California, Mexico (40 km south of the U.S.- Mexico border). Only 1 of the 26 known populations is known to have been extirpated, but most of the 25 extant populations have been reduced and fragmented by recent urban and agricultural development: a 50% decline in the number of individuals has been estimated since 1982. There are now approximately 9,000-10,000 individuals remaining in the U.S. and an unknown number remaining in the 5 Mexican populations. Approximately 82-93% of the species' maritime chaparral habitat in the U.S. has been lost to development, and development in northwestern Baja Califoria has been similarly intense. Remaining habitat is highly fragmented; most of the surviving plants are near the margins of residential developments. Proposed and ongoing development is the most imminent threat facing the species; associated change in the natural fire cycle is also a threat.

01/01/2010

Approximately 82-93% of the species' maritime chaparral habitat in the U.S. has been lost to development, and development in northwestern Baja Califoria has been similarly intense. Remaining habitat is highly fragmented; most of the surviving plants are n

01/01/2010

Only 1 of the 26 known populations is known to have been extirpated, but most of the 25 extant populations have been reduced and fragmented by recent urban and agricultural development: a 50% decline in the number of individuals has been estimated since 1982. There are now approximately 9,000-10,000 individuals remaining in the U.S. and an unknown number remaining in the 5 Mexican populations.

01/01/2010

This species is considered and provided some protection and management guidelines under a local Multiple Species Conservation Plan (MSCP). Management actions called for within this plan are 1.) preservation of the majority of the remaining populations within the subregion including two major populations; 2.) plans to address impacts from fuel management and proximity to exisitng and proposed development; 3.) monitoring of the status of these populations. The final ruling Federal Register document October 7, 1996 page 52383 states that ""Some populations within this subregion will be eliminated or reduced, but it has been determined that the populations preserved under the plan will be adequate to stabilize the status of this taxon within the MSCP planning area."" Federal Register document Vol. 61, No. 195 October 7, 1996 pages 52370 to 52384

01/01/2010

Population surveys, monitoring, assessment of threats and impacts to population sites

01/01/2010

Collect, develop and maintain germplasm collections from the most at risk remaining sites throughout the plants range. Develop effective seed germination protocols