Astragalus brauntonii
Encyclopedia
Astragalus brauntonii is a rare species of milkvetch
known by the common name Braunton's milkvetch. It is endemic to southern California
, where it is known from fewer than 20 extant occurrences in the hills and mountains surrounding Los Angeles
. It is a plant of the coastal prairie
grassland
s, coastal sage scrub
, and chaparral
plant communities of the region, especially in carbonate soils
areas.
and reaches up to 1.5 metres (4.9 ft) tall. The thick hollow stems are coated in coarse white hairs. Leaves are up to 16 centimetres (6.3 in) long and are made up of many pairs of oval-shaped leaflike leaflets.
The inflorescence
is a dense spike of up to 60 bright lilac flowers. Each pealike flower is about a centimeter long with a reflexed hood. The flowers wither and turn brown but remain on the plant instead of dropping off. The fruit is a small bent legume pod.
or other disturbance to propagate. The beanlike seeds require scarification
to break down their tough seed coats before they can germinate. The seeds persist for years in the soil until fire allows them to sprout, with populations of the plant springing up in an area that has been recently swept by wildfire. It is a pioneer species
, one of the first to grow in a disturbed area and one that is soon crowded out by plant species that appear later in ecological succession
. Wildfire suppression in the hills and mountains surrounding Los Angeles prevent the plant from reproducing. This is a federally listed endangered species
in the United States.
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 name Braunton's milkvetch. It is endemic to southern 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...
, where it is known from fewer than 20 extant occurrences in the hills and mountains surrounding Los Angeles
Los Angeles, California
Los Angeles , with a population at the 2010 United States Census of 3,792,621, is the most populous city in California, USA and the second most populous in the United States, after New York City. It has an area of , and is located in Southern California...
. It is a plant of the coastal prairie
California coastal prairie
California coastal prairie, also known as northern coastal grassland, is a grassland plant community of California and Oregon in the Temperate grasslands, savannas, and shrublands Biome...
grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
s, coastal sage scrub
Coastal sage scrub
Coastal sage scrub is a low scrubland plant community found in the California chaparral and woodlands ecoregion of coastal California and northern Baja California. It is characterized by low-growing aromatic, and drought-deciduous shrubs adapted to the semi-arid Mediterranean climate of the...
, and 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...
plant communities of the region, especially in carbonate soils
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....
areas.
Description
Braunton's milkvetch is a large perennial herb which grows from a woody caudexCaudex
A caudex is a form of stem morphology appearing as a thickened, short, perennial stem that is either underground or near ground level . It may be swollen for the purpose of water storage, especially in xerophytes...
and reaches up to 1.5 metres (4.9 ft) tall. The thick hollow stems are coated in coarse white hairs. Leaves are up to 16 centimetres (6.3 in) long and are made up of many pairs of oval-shaped leaflike leaflets.
The inflorescence
Inflorescence
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...
is a dense spike of up to 60 bright lilac flowers. Each pealike flower is about a centimeter long with a reflexed hood. The flowers wither and turn brown but remain on the plant instead of dropping off. The fruit is a small bent legume pod.
Fire ecology
This plant, like many chaparral species, is fire-adapted and requires wildfireWildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
or other disturbance to propagate. The beanlike seeds require scarification
Scarification (botany)
Scarification in botany involves cutting the seed coat using abrasion, thermal stress, or chemicals to encourage germination.-In botany:Scarification is a natural process important for germination of many species' seeds. This process involves the breaching of the natural seed coating by mechanical,...
to break down their tough seed coats before they can germinate. The seeds persist for years in the soil until fire allows them to sprout, with populations of the plant springing up in an area that has been recently swept by wildfire. It is a pioneer species
Secondary succession
Secondary succession is one of the two types of ecological succession of plant life. As opposed to the first, primary succession, secondary succession is a process started by an event that reduces an already established ecosystem Secondary succession is one of the two types of ecological...
, one of the first to grow in a disturbed area and one that is soon crowded out by plant species that appear later in ecological succession
Ecological succession
Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a fundamental concept in ecology, and refers to more or less predictable and orderly changes in the composition or structure of an ecological community...
. Wildfire suppression in the hills and mountains surrounding Los Angeles prevent the plant from reproducing. This 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...
in the United States.