Astragalus albens
Encyclopedia
Astragalus albens is a species of milkvetch
known by the common names Cushenbury milkvetch and silvery-white milkvetch.
, where it is known from the northern slopes of the San Bernardino Mountains
. Most of the plants are located in the woodland and scrub of the slopes between Big Bear
in the mountains and Lucerne Valley in the Mojave Desert
at the foot of the range.
It grows in habitat rich in carbonate
rock. It is a federally listed endangered species
which is known from 30 to 50 populations. There are a total of about 7000 plants, fewer in drought
years.
arises upright from the low patch of foliage and bears up to 14 pealike flowers. Each flower is dark-veined light to deep purple with a spot of white or light pink in the throat.
The fruit is a legume pod between one and two centimeters long. It is roughly hairy and crescent-shaped, drying to a thick papery texture.
mining, a large industry in this part of the San Bernardino Mountains. This form of mining alters the local habitat by physically removing plant life for quarries
, road construction
, and load dumping. It also produces major changes in the hydrology
of the area and releases large amounts of carbonate dust into the air which combines with water and forms a very thin layer of what is essentially cement
over the habitat. Most of the populations of this plant are located on sites of active mining or sites which are targeted for mining in the future.
Most of these sites are part of San Bernardino National Forest
, and there are plans to set aside pieces of habitat for this and other endemics. Other threats to the species include off-road vehicle
use and urban development
.
Astragalus
Astragalus is a large genus of about 3,000 species of herbs and small shrubs, belonging to the legume family Fabaceae, subfamily Faboideae. The genus is native to temperate regions of the Northern Hemisphere...
known by the common names Cushenbury milkvetch and silvery-white milkvetch.
Distribution
It is endemic to San Bernardino County, CaliforniaSan Bernardino County, California
San Bernardino County is a county in the U.S. state of California. As of the 2010 census, the population was 2,035,210, up from 1,709,434 as of the 2000 census...
, where it is known from the northern slopes of the San Bernardino Mountains
San Bernardino Mountains
The San Bernardino Mountains are a short transverse mountain range north and east of San Bernardino in Southern California in the United States. The mountains run for approximately 60 miles east-west on the southern edge of the Mojave Desert in southwestern San Bernardino County, north of the...
. Most of the plants are located in the woodland and scrub of the slopes between Big Bear
Big Bear Lake
Big Bear Lake is a reservoir in the San Bernardino Mountains, in San Bernardino County, California, United States. At a surface elevation of , it has an east-west length of approximately 7 miles and is approximately 2.5 miles at its widest measurement, though the lake's width mostly averages a...
in the mountains and Lucerne Valley in the Mojave Desert
Mojave Desert
The Mojave Desert occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
at the foot of the range.
It grows in habitat rich in carbonate
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
rock. It is a federally listed 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...
which is known from 30 to 50 populations. There are a total of about 7000 plants, fewer in drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
years.
Description
Astragalus albens is an annual or perennial herb producing a prostrate mat of delicate stems coated densely in silvery hairs. The leaves are generally a few centimeters long and made up of several gray-green oval-shaped leaflets less than a centimeter long each. The inflorescenceInflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
arises upright from the low patch of foliage and bears up to 14 pealike flowers. Each flower is dark-veined light to deep purple with a spot of white or light pink in the throat.
The fruit is a legume pod between one and two centimeters long. It is roughly hairy and crescent-shaped, drying to a thick papery texture.
Conservation
The main threat to this species is limestoneLimestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
mining, a large industry in this part of the San Bernardino Mountains. This form of mining alters the local habitat by physically removing plant life for quarries
Quarry
A quarry is a type of open-pit mine from which rock or minerals are extracted. Quarries are generally used for extracting building materials, such as dimension stone, construction aggregate, riprap, sand, and gravel. They are often collocated with concrete and asphalt plants due to the requirement...
, road construction
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...
, and load dumping. It also produces major changes in the hydrology
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
of the area and releases large amounts of carbonate dust into the air which combines with water and forms a very thin layer of what is essentially cement
Cement
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...
over the habitat. Most of the populations of this plant are located on sites of active mining or sites which are targeted for mining in the future.
Most of these sites are part of San Bernardino National Forest
San Bernardino National Forest
San Bernardino National Forest is a federally-managed forest covering more than 800,000 acres . There are two main divisions which are the San Bernardino Mountains on the easternmost of the Transverse Range, and the San Jacinto and Santa Rosa Mountains on the northernmost of the Peninsular...
, and there are plans to set aside pieces of habitat for this and other endemics. Other threats to the species include off-road vehicle
Off-road vehicle
An off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with deep, open treads, a flexible suspension, or even caterpillar tracks...
use and urban development
Urban planning
Urban planning incorporates areas such as economics, design, ecology, sociology, geography, law, political science, and statistics to guide and ensure the orderly development of settlements and communities....
.