CPC National Collection Plant Profile

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CPC National Collection Plant Profile

Arctostaphylos glandulosa ssp. crassifolia


Family: 
Ericaceae  
Common Names: 
Del Mar manzanita, Costa Baja manzanita, Eastwood manzanita
Author: 
(Jepson) P. Wells
Growth Habit: 
Shrub
CPC Number: 
216

Distribution
Protection
Conservation
References


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Arctostaphylos glandulosa ssp. crassifolia is Not Sponsored
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Arctostaphylos glandulosa ssp. crassifolia


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. This manzanita species, like itís 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. 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.

Distribution & Occurrence

State Range
  California
State Range of  Arctostaphylos glandulosa ssp. crassifolia
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.

Distribution
  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).

Number Left
  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.

Protection

Global Rank:  
G5T1
 
3/8/1999
Guide to Global Ranks
Federal Status:  
LE
 
10/7/1996
Guide to Federal Status
Recovery Plan:  
No
 

State/Area Protection
  State/Area Rank Status Date  
  California S1.1  

Conservation, Ecology & Research

Ecological Relationships
 

Threats
  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.

This plant species is considered seriously endangered by the California Native Plant Society (CNPS 1B red code 333).

Current Research Summary
 

Current Management Summary
  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

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

Ex Situ Needs
  Collect, develop and maintain germplasm collections from the most at risk remaining sites throughout the plants range.

Develop effective seed germination protocols

References

Books (Edited Volumes)

James C. Hickman, Editor. 1993 The Jepson Manual. Berkeley, California: University of California Press.

Electronic Sources

California Native Plant Society (CNPS). (2003). Inventory of Rare and Endangered Plants (online edition, v6.2). Rare Plant Scientific Advisory Committee, David P. Tibor, convening editor. v6.2. http://www.cnps.org/inventory.

Reiser, C.H. (1994). http://sandiego.sierraclub.org/rareplants/010.html.


  This profile was updated on 3/4/2010
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