Arabis dispar - M.E. Jones
Unequal Rockcress
Synonym(s): Boechera dispar (M. E. Jones) Al-Shehbaz
Taxonomic Status: Accepted
Related ITIS Name(s): Arabis dispar M.E. Jones (TSN 22687)
Unique Identifier: ELEMENT_GLOBAL.2.157137
Element Code: PDBRA060F0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Mustard Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Capparales Brassicaceae Arabis
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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: Arabis dispar
Conservation Status
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NatureServe Status

Global Status: G3
Global Status Last Reviewed: 02Feb2009
Global Status Last Changed: 06Aug1987
Rounded Global Status: G3 - Vulnerable
Reasons: Arabis dispar occurs on loose gravelly slopes and compact talus in the desert ranges of southeastern California east to Nye County, Nevada. Approximately 19 occurrences are currently believed extant; most are in California. Appears to be locally common at a few sites, but rangewide abundance is unknown. There are no active threats to this species in Nevada; potential threats are from mining, development, and military/DOE activities. In California, threats also seem minimal; a few occurrences may be threatened by military uses, grazing, mining, road construction, and/or non-native plants.
Nation: United States
National Status: N3

U.S. & Canada State/Province Status
United States California (S3), Nevada (S1S2)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Holmgren et al. (2005) describe the range as "southeast California from the White Mountains south through the Panamint and Argus mountains to the San Bernardino and Little San Bernardino Mountains; disjunct in Nevada in Mineral County (Huntoon Mountains) and southern Nye County (Eleana Range)." In California, this species is mapped by the California Natural Diversity Database (CNDDB) in Inyo, Mono, San Bernardino, and Tulare counties. The California Native Plant Society (2009) shows one additional mapped site in Los Angeles County - more details are needed on this report. Excluding Los Angeles County, range extent was calculated to be approximately 40,000 square km.

Area of Occupancy: 26-500 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 6 - 80
Number of Occurrences Comments: Nineteen occurrences are currently believed extant (15 in California and 4 in Nevada); an additional 9 occurrences are considered historical (all in California). There may be additional occurrences in Nevada that have not been recorded and/or processed yet (Nevada Natural Heritage Program 1999). Known from few sites in 1993; Rollins (1993) commented that "to my knowledge, it has been collected scarcely more than a dozen times totally, sometimes from the same site."

Population Size Comments: Considered "rare" rangewide, but locally common at least at a few locations (Kartesz 1988, Holmgren et al. 2005). Described as "common" at one Nevada site, "locally common" at two Nevada sites and one California site, "not uncommon" at one California site, and "scarce" at one California site. Another California site had 100-200 plants in a 1998 survey. The species is apparently considered "rare" in San Bernardino County, where there is one occurrence currently believed extant. No information about abundance is available for the other eleven sites believed extant, so total population size cannot be estimated.

Viability/Integrity Comments: At least two occurrences in Calfornia are estimated to have excellent or good viability; other presumed extant occurrences have not yet been assigned a rank.

Overall Threat Impact Comments: There are no active threats known in Nevada, only potential threats from mining, development, and military/Department of Energy activities (Jim Morefield, personal communication 1999). Threats in California also seem minimal, although a few occurrences may be threatened by military uses, grazing, mining, road construction, and/or non-native plants (R. Bittman pers. comm. 2009, CNPS 2009).

Other NatureServe Conservation Status Information

Distribution
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Global Range: Holmgren et al. (2005) describe the range as "southeast California from the White Mountains south through the Panamint and Argus mountains to the San Bernardino and Little San Bernardino Mountains; disjunct in Nevada in Mineral County (Huntoon Mountains) and southern Nye County (Eleana Range)." In California, this species is mapped by the California Natural Diversity Database (CNDDB) in Inyo, Mono, San Bernardino, and Tulare counties. The California Native Plant Society (2009) shows one additional mapped site in Los Angeles County - more details are needed on this report. Excluding Los Angeles County, range extent was calculated to be approximately 40,000 square km.

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

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

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Inyo (06027), Mono (06051), Riverside (06065), San Bernardino (06071), Tulare (06107)*
NV Mineral (32021), Nye (32023)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Sand Spring-Tikaboo Valleys (16060014)+
18 South Fork Kern (18030002)+*, Santa Ana (18070203)+, Crowley Lake (18090102)+, Owens Lake (18090103)+, Eureka-Saline Valleys (18090201)+, Death Valley-Lower Amargosa (18090203)+*, Panamint Valley (18090204)+, Indian Wells-Searles Valleys (18090205)+, Mojave (18090208)+, Southern Mojave (18100100)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: Perennial herb with numerous, erect, spatulate to linear-oblanceolate, entire basal leaves and broadly linear, sessile cauline leaves that are reduced upward. The flower's petals are purplish (Rollins 1993). Blooms (March-)April-May(-June).
Terrestrial Habitat(s): Bare rock/talus/scree, Desert, Forest/Woodland, Shrubland/chaparral, Woodland - Conifer
Habitat Comments: Loose gravelly slopes and compact talus, often on granitic substrates. These slopes are found within plant communities including sagebrush scrub, pinyon-juniper woodland, Joshua tree "woodland", and Mojavean desert scrub. 1200 - 2540 m.
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
Help
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: 20May2003
NatureServe Conservation Status Factors Author: Gries, D., L. Oliver, rev. K. Gravuer (2009)

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
Help
  • Al-Shehbaz, I. A. 2003. Transfer of most North American Species of Arabis to Boechera (Brassicaceae). Novon 13: 381-391.

  • California Department of Fish and Game. 2000. Natural Diversity Database (RareFind 2), Version 2.1.2, January 25, 2000. Downloaded in 2003.

  • California Native Plant Society (CNPS). 2009. Inventory of Rare and Endangered Plants. California Native Plant Society. Sacramento, CA. Online. Available: http://www.cnps.org/inventory (accessed 2009).

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

  • Holmgren, N.H., P.K. Holmgren, and A. Cronquist. 2005. Intermountain flora. Volume 2, part B. Subclass Dilleniidae. The New York Botanical Garden Press. 488 pages.

  • Kartesz, J.T. 1988. A flora of Nevada. Ph.D. dissertation. Univ. of Nevada, Reno. 3 volumes. 1729 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.

  • Nevada Natural Heritage Program. 1999. February 19-last update. List of sensitive plants. Online. Available: http://www.state.nv.us/nvnhp/sensplnt.htm. Accessed 1999, June 3.

  • Rollins, R.C. 1993a. The Cruciferae of continental North America: Systematics of the mustard family from the Arctic to Panama. Stanford Univ. Press, Stanford, California. 976 pp.

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