Arctostaphylos pallida
Encyclopedia
Arctostaphylos pallida, commonly known as Pallid Manzanita, Oakland Hills Manzanita, and Alameda Manzanita, is an upright Manzanita
shrub from the Ericaceae
, or heath family. It is endemic to the eastern San Francisco Bay Area
of Northern California
.
The dense, white flowers are urn-shaped and 0.2 to 0.3 inches (7.6 mm) long. The flowering period is from November to March.
A. pallida commonly co-occurs with another manzanita species, Brittle Leaf Manzanita (Arctostaphylos tomentosa
ssp. crustacea), but the latter is a burl
-forming species with spreading leaves. A. pallida does not form burls.
and shale
. The plants are found in manzanita chaparral habitat of the montane chaparral and woodlands
ecosystem, and is frequently surrounded by oak woodlands
and other chaparral
shrubs.
Endemism
Arctostaphylos pallida is known from approximately 13 populations in Alameda
and Contra Costa
counties. The two largest populations, which are owned by the East Bay Regional Park District
, are located at Huckleberry Ridge—Huckleberry Botanic Regional Preserve
in Alameda and Contra Costa Counties and at Sobrante Ridge Regional Park
in Contra Costa County.
Several other small, natural and planted populations occur in Alameda and Contra Costa counties. The two largest groups occupy an area of approximately 82 acres (331,842.5 m²). These two populations are found in maritime sage and chaparral, a habitat with mesic soil conditions and a maritime influence. Many smaller populations occur in coastal scrub.
s, and introduced
and invasive species
. To a lesser extent, the species is threatened by fungal infection, herbicide spraying, hybridization, construction of road
s, and the ongoing effects of habitat fragmentation
and loss.
This is a federally listed threatened species. It was listed as an endangered species
by the California Department of Fish and Game
in November 1997. The California Native Plant Society
has placed it on List 1B (rare or endangered throughout its range).
Manzanita
Manzanita is a common name for many species of the genus Arctostaphylos. They are evergreen shrubs or small trees present in the chaparral biome of western North America, where they occur from southern British Columbia, Washington to California, Arizona and New Mexico in the United States, and...
shrub from the Ericaceae
Ericaceae
The Ericaceae, commonly known as the heath or heather family, is a group of mostly calcifuge flowering plants. The family is large, with roughly 4000 species spread across 126 genera, making it the 14th most speciose family of flowering plants...
, or heath family. It is endemic to the eastern San Francisco Bay Area
San Francisco Bay Area
The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...
of Northern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
Description
Arctostaphylos pallida grows to around 6–13 ft (1.8–4 m) in height. The branches on the shrub are reddish or grayish (more reddish) and they have twigs that tend to be bristly. The ovate to triangular leaves are bristly, strongly overlapping and clasping. They are 1.0 to 1.8 inches (45.7 mm) long and 0.8 to 1.2 inches (30.5 mm) wide.The dense, white flowers are urn-shaped and 0.2 to 0.3 inches (7.6 mm) long. The flowering period is from November to March.
A. pallida commonly co-occurs with another manzanita species, Brittle Leaf Manzanita (Arctostaphylos tomentosa
Arctostaphylos tomentosa
Arctostaphylos tomentosa is a species of manzanita known by the common name woollyleaf manzanita. This shrub is endemic to California where it is a resident of chaparral canyons, foothills, and lower-elevation mountains. One specialized habitat in which A...
ssp. crustacea), but the latter is a burl
Burl
A burl or bur or burr is a tree growth in which the grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds.A burl results from a tree undergoing some form of stress. It may be caused...
-forming species with spreading leaves. A. pallida does not form burls.
Distribution
The species is found from 656–1460 ft (199.9–445 m) in elevation, primarily on thin soils composed of chertChert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
. The plants are found in manzanita chaparral habitat of the montane chaparral and woodlands
California montane chaparral and woodlands
The California montane chaparral and woodlands ecoregion covers , including the mountains of the Transverse, Peninsular, and Santa Lucia Ranges of California. It is part of the Mediterranean forests, woodlands, and scrub biome, with cool, wet winters and hot, dry summers...
ecosystem, and is frequently surrounded by oak woodlands
California oak woodland
California oak woodland is a plant community found throughout the California chaparral and woodlands ecoregion of California in the United States and northwestern Baja California in Mexico...
and other chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
shrubs.
Endemism
Arctostaphylos pallida is known from approximately 13 populations in Alameda
Alameda County, California
Alameda County is a county in the U.S. state of California. It occupies most of the East Bay region of the San Francisco Bay Area. As of the 2010 census it had a population of 1,510,271, making it the 7th most populous county in the state...
and Contra Costa
Contra Costa County, California
Contra Costa County is a primarily suburban county in the San Francisco Bay Area of the U.S. state of California. As of the 2010 census, it had a population of 1,049,025...
counties. The two largest populations, which are owned by the East Bay Regional Park District
East Bay Regional Park District
The East Bay Regional Park District is a special district operating in Alameda County and Contra Costa County, California, within the East Bay area of the San Francisco Bay Area...
, are located at Huckleberry Ridge—Huckleberry Botanic Regional Preserve
Huckleberry Botanic Regional Preserve
Huckleberry Botanic Regional Preserve is a regional park and nature reserve in the eastern San Francisco Bay Area, in Alameda and Contra Costa Counties, Northern California. It is a park within the East Bay Regional Parks District system...
in Alameda and Contra Costa Counties and at Sobrante Ridge Regional Park
Sobrante Ridge Regional Park
Sobrante Ridge Regional Park, or simply Sobrante Ridge, is a regional park of the East Bay Regional Parks District in Richmond, California. It covers and protects the extremely endangered Alameda Manzanita, a native plant of the area...
in Contra Costa County.
Several other small, natural and planted populations occur in Alameda and Contra Costa counties. The two largest groups occupy an area of approximately 82 acres (331,842.5 m²). These two populations are found in maritime sage and chaparral, a habitat with mesic soil conditions and a maritime influence. Many smaller populations occur in coastal scrub.
Threats
The primary threats to the species are the effects of fire suppression, and shading and competition from native plantNative plant
Native plant is a term to describe plants endemic or naturalized to a given area in geologic time.This includes plants that have developed, occur naturally, or existed for many years in an area...
s, and introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
and invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
. To a lesser extent, the species is threatened by fungal infection, herbicide spraying, hybridization, construction of road
Road
A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...
s, and the ongoing effects of habitat fragmentation
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
and loss.
This is a federally listed threatened species. It was listed as an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
by the California Department of Fish and Game
California Department of Fish and Game
The California Department of Fish and Game is a department within the government of California, falling under its parent California Natural Resources Agency. The Department of Fish and Game manages and protects the state's diverse fish, wildlife, plant resources, and native habitats...
in November 1997. The California Native Plant Society
California Native Plant Society
The California Native Plant Society is a California not-for-profit organization that seeks to increase understanding of California's native flora and to preserve that flora. Its "paramount purpose is to preserve wild plants".-History:...
has placed it on List 1B (rare or endangered throughout its range).
See also
- List of California native plants
- Index: Endemic flora of California