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Home/Species/ Braunton's Milkvetch

Astragalus brauntonii

Parish

Braunton's Milkvetch

G2Imperiled Found in 13 roadless areas NatureServe Explorer →
G2ImperiledGlobal Rank
Very high - mediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.156760
Element CodePDFAB0F1G0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single state or province
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderFabales
FamilyFabaceae
GenusAstragalus
Other Common Names
Braunton's milkvetch (EN)
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Review Date2016-07-27
Change Date1988-03-08
Edition Date2003-07-24
Edition AuthorsBittman, R.L., rev. Maybury (1997), L. Oliver (2003)
Threat ImpactVery high - medium
Range Extent250-20,000 square km (about 100-8000 square miles)
Number of Occurrences6 - 20
Rank Reasons
Endemic to the mountains surrounding the Los Angeles basin, California, where it is currently known from 4 general areas. Currently, fewer than 100 individual plants are known, but the species' seed bank could generate larger populations if appropriate fire events occurred. The species may be restricted to limestone, which is a rare substrate within the limits of its known distribution. A. brauntonii is threatened by urban development and habitat fragmentation, and by the resultant alteration of natural fire cycles. The fact that the plants are only visible for 2-3 years following a fire or other disturbance (which may occur only once in 20-50+ years) may make the populations especially vulnerable to destruction.
Range Extent Comments
Foothills bordering the Los Angeles plain, from the Santa Monica, Santa Ana and San Gabriel Mtns. Los Angeles, River- side, Ventura and Orange counties, California.
Occurrences Comments
10 sites presumed extant; 5 probably extirpated; one erron- eous.
Threat Impact Comments
This species requires a fire regime and while the frequency of the required regime is unknown, estimates are between 20 and 100 years. Depending on the natural fire regime, plant populations are only visible every 20 to 50 years. More frequent fires have altered the habitat, and these fires are caused by arson (USFWS 1997, CNPS 2001, CNDDB 2003). This species is also threatened by urban development, fragmentation of habitat and reduced capability for sustained ecologic processes, fragmented ownership of single populations resulting in different landscape treatments, and extinction from natural occurring events due to small populations sizes and low individual numbers (USFWS 1997).
Ecology & Habitat

Description

"Young plants are herbaceous down to the ground, but after a year or two develop a ligneous trunk several centimeters in diameter. The species is easily recognized by its tall, fistular stems whitened by a coat of spreading or entangled hairs, by the ample leaves composed of 12-16 pairs of dorsally keeled leaflets, and especially by the narrow, dense racemes of small, nodding, purplish flowers which arise from several distal axils and form a sort of panicle of spikes. As the flowers fade the petals turn brown and papery, investing with the somewhat accrescent calyx the base of the forming pod; they are not promptly shed as in most of the genus" (Barneby, 1964).

Diagnostic Characteristics

Stem erect to widely ascending, 60-150 cm. Flowers refexed; corolla dull lilac; fruit reflexed, deciduous, <10 mm, densely wavy-hairy.

Habitat

Brush/chaparral communities. The seeds germinate after fire or other disturbance and the plants live only 2-3 years before senescing or being crowded out by developing vegetation. The natural frequency of fire in the species' habitat is unknown. The plants may be restricted to limestone substrates.
Terrestrial Habitats
Shrubland/chaparral
Other Nations (1)
United StatesN2
ProvinceRankNative
CaliforniaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentPervasive (71-100%)Extreme or 71-100% pop. declineHigh (continuing)
1.1 - Housing & urban areasPervasive (71-100%)Extreme or 71-100% pop. declineHigh (continuing)
7 - Natural system modificationsPervasive (71-100%)Extreme or 71-100% pop. declineHigh (continuing)
7.1 - Fire & fire suppressionPervasive (71-100%)Extreme or 71-100% pop. declineHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)Yes
Roadless Areas (13)
California (13)
AreaForestAcres
Arroyo SecoAngeles National Forest4,703
Cucamonga AAngeles National Forest1,249
Cucamonga BSan Bernardino National Forest11,933
Cucamonga CSan Bernardino National Forest4,106
LaddCleveland National Forest5,300
Magic MountainAngeles National Forest15,542
San DimasAngeles National Forest7,160
San Gabriel AddAngeles National Forest2,527
San SevaineSan Bernardino National Forest6,866
Sheep MountainAngeles National Forest21,098
Strawberry PeakAngeles National Forest7,245
West ForkAngeles National Forest1,169
WestforkAngeles National Forest4,407
References (7)
  1. Barneby, R.C. 1964. Atlas of North American Astragalus. 2 Vols. New York Botanical Garden, Bronx, New York. 1188 pp.
  2. California Department of Fish and Game. 2000. Natural Diversity Database (RareFind 2), Version 2.1.2, January 25, 2000. Downloaded in 2003.
  3. California Native Plant Society (CNPS). 2001. Inventory of Rare and Endangered Plants of California (sixth edition). Rare Plant Scientific Advisory Committee, David P. Tibor, Convening Editor. California Native Plant Society. Sacramento, CA. x + 388pp.
  4. Hickman, J. C., ed. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 1400 pp.
  5. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  6. U.S. Fish and Wildlife Service (USFWS). 1997. Determination of endangered status for two plants and threatened status for four plants from southern California. Federal Register 62(19): 4172-4183.
  7. U.S. Fish and Wildlife Service (USFWS). 1997. Determination of endangered status for two plants and threatened status for four plants from Southern California. Federal Register 62(19):4172-4183. 29 January 1997.