Astragalus preussii var. laxiflorus - A. Gray
Lancaster Milkvetch
Taxonomic Status: Accepted
Related ITIS Name(s): Astragalus preussii var. laxiflorus Gray (TSN 192701)
Unique Identifier: ELEMENT_GLOBAL.2.138949
Element Code: PDFAB0F721
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pea Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Fabales Fabaceae Astragalus
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Concept Reference
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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.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Astragalus preussii var. laxiflorus
Taxonomic Comments: Nevada-Arizona and California occurrence clusters may be two distinct taxa; reports from Utah are likely erroneous (J. Morefield, pers. comm. 2008).
Conservation Status
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NatureServe Status

Global Status: G4T2
Global Status Last Reviewed: 16Apr2008
Global Status Last Changed: 16Apr2008
Rounded Global Status: T2 - Imperiled
Reasons: Known only from the area around Lake Mead (Nevada-Arizona) in the lower Muddy and Virgin valleys, and disjunctly in northeastern Los Angeles County (Lancaster), California. Approximately 13 occurrences are believed extant, 7 in Nevada, 3 in Arizona, and 3 in California. Likely declining in the California portion of the range, but not precipitously. This taxon is also potentially in Utah (near the NV-AZ sites).
Nation: United States
National Status: N2?

U.S. & Canada State/Province Status
United States Arizona (S1), California (S1), Nevada (S1S2)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Known only from the area around Lake Mead (Nevada-Arizona) and disjunctly in northeastern Los Angeles County (Lancaster), California. This taxon has also been reported from Utah (near the NV-AZ sites), but these reports may be erroneous (J. Morefield, pers. comm. 2008). Range extent is approximately 1000-2000 square km, not including the area between the NV-AZ cluster of occurrences and the CA occurrences (which is not considered to be suitable habitat).

Area of Occupancy: 26-500 4-km2 grid cells
Area of Occupancy Comments: Using a 2 x 2 km grid, AOO is estimated to be approximately 48 - 56 square km.

Number of Occurrences: 6 - 20
Number of Occurrences Comments: Approximately 13 occurrences are believed extant, 7 in Nevada, 3 in Arizona, and 3 in California. Some Nevada occurrences have not be revisited recently, but they are located in remote areas where they are likely to persist, and so are presumed extant. It is believed that a few, but not many, additional EOs might be found with intensive survey of suitable habitat in range.

Population Size Comments: Generally uncommon, although Nevada botanists are seeing it frequently in the Lake Mead area (J. Morefield, pers. comm. 2008).

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: Likely declining in the California portion of the range.

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: Probably declining somewhat, but long-term trend believed relatively stable.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Known only from the area around Lake Mead (Nevada-Arizona) and disjunctly in northeastern Los Angeles County (Lancaster), California. This taxon has also been reported from Utah (near the NV-AZ sites), but these reports may be erroneous (J. Morefield, pers. comm. 2008). Range extent is approximately 1000-2000 square km, not including the area between the NV-AZ cluster of occurrences and the CA occurrences (which is not considered to be suitable habitat).

U.S. States and Canadian Provinces
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States AZ, CA, NV

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
AZ Mohave (04015)
CA Kern (06029), Los Angeles (06037), Riverside (06065)*
NV Clark (32003)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
15 Lake Mead (15010005)+, Grand Wash (15010006)+, Las Vegas Wash (15010015)+*, Havasu-Mohave Lakes (15030101)+*
16 Ivanpah-Pahrump Valleys (16060015)+*
18 Antelope-Fremont Valleys (18090206)+, Whitewater River (18100201)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: An ill-scented, pink-flowered locoweed (Fabaceae).
Technical Description: Perennial but sometimes flowering the first season, rather coarse and robust, glabrous or nearly so below the inflorescence, the few hairs when present, either filiform or scalelike, appressed up to 0.1-0.5 mm. long, confined to the margins and midrib of the leaflets, the malodorous herbage green or yellowish-green, somewhat leathery; stems several, erect and ascending, (0.7) 1-3.5 dm long, simple or few-branched below the middle. Leaves (3.5) 4.5-18 cm long, shortly petioled or the uppermost subsessile, with stiff rachis and (7) 11-25 rather distant leaflets 1.5-27 mm long, these varying in shape from suborbicular-obcordate through oblong-obovate to linear-elliptic, narrowly lanceolate, or linear and acute. Infloresence open; racemes loosely (3) 4-16 (22)-flowered, the axis 4-23 cm long in fruit; bracts membranous, pallid or purplish, ovate or lanceolate, 1.5-4mm long; pedicels ascending, straight, at anthesis (1) 1.5-2.8 mm; bracteoles nearly always 2, sometimes minute; calyx (6.4) 8-9.4 mm long, thinly strigulose with black or mixed black and white hairs. Flowers pink or when dried bluish-purple, sometimes pallid but distally suffused with lilac-purple, banner about 14 mm. Pod sessile or nearly so, oblong-elipsoid; more or less round in cross-section, stiffly papery. Ovules smooth or nearly so, sometimes mottled with dull purple, 2.4-3.7 mm long.
Diagnostic Characteristics: Fruit base not stalk-like; infloresence open, axis in fruit 4-23 cm; banner more or less 14 mm.
Duration: PERENNIAL
Ecology Comments: Gravelly or sandy washes and along gullied badlands from 1200-2500 feet. Also grows on alkaline clay flats in the southwest Mohave Desert. May prefer selenium rich soils.
Terrestrial Habitat(s): Desert, Playa/salt flat
Habitat Comments: Gravelly or sandy desert washes, alkaline desert playas. 360 - 750 m.
Economic Attributes
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Economically Important Genus: Y
Management Summary
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Stewardship Overview: This very rare native plant has had very little research done on its basic biology and its needs are almost completely unknown.
Preserve Selection & Design Considerations: Requires sandy or gravelly washes along draws in gullied badlands. Often grows in selenium rich soils.
Monitoring Requirements: Historic and potential habitat of species, particularly in the California portion of its range, should be surveyed.
Management Research Needs: All aspects of the basic biology of this species require more research.
Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 05May2008
NatureServe Conservation Status Factors Author: Gravuer, K.
Management Information Edition Date: 06Jul1995
Management Information Edition Author: Michael Schindel
Element Ecology & Life History Edition Date: 05Jul1995
Element Ecology & Life History Author(s): Michael Schindel

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Barneby, R.C. 1964. Atlas of North American Astragalus. 2 Vols. New York Botanical Garden, Bronx, New York. 1188 pp.

  • Fuller, T.C., and E. McClintock. 1986. Poisonous Plants of California. University of California Press. 433 pp.

  • Hickman, J. C., ed. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 1400 pp.

  • 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.

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