Ivesia webberi - Gray
Webber Ivesia
Other English Common Names: Wire Mousetail
Other Common Names: wire mousetail
Taxonomic Status: Accepted
Related ITIS Name(s): Ivesia webberi Gray (TSN 25241)
Unique Identifier: ELEMENT_GLOBAL.2.151761
Element Code: PDROS0X0Q0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Rose Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Rosales Rosaceae Ivesia
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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: Ivesia webberi
Conservation Status
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NatureServe Status

Global Status: G2
Global Status Last Reviewed: 03Jun2014
Global Status Last Changed: 17Apr1985
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G2 - Imperiled
Reasons: Ivesia webberi is known from 14 extant occurrences scattered over a small portion of northeastern California and western Nevada. Many are vulnerable to encroaching residential development and attendant off-road vehicle and recreational use, and to livestock grazing. It occurs densely in some places,with more than 4,000,000 individual plants, but total occupied area is only about 200 acres.
Nation: United States
National Status: N2

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States California (S1), Nevada (S2)

Other Statuses

U.S. Endangered Species Act (USESA): LT: Listed threatened (03Jun2014)
U.S. Fish & Wildlife Service Lead Region: R8 - California-Nevada

NatureServe Global Conservation Status Factors

Range Extent Comments: Found in Sierra, Dog and Honey Lake Valleys, Sierra and Lassen Counties, Western Nevada and adjacent eastern California. Known from Upper Long Valley on the California-Nevada border, and elsewhere in Nevada from both north and southwest of Reno, Washoe County, and from the western slope of the Pine Nut Mountains, Douglas County. When the disjunct Douglas County, Nevada, occurrence is excluded, range extent decreases from about 1600 km2 to under 1000 km2. California drew a least square around the known occurrences in 2005 and estimated range size there as 2800 sq mi.

Area of Occupancy: 1-25 4-km2 grid cells
Area of Occupancy Comments: The known occurrences occupy a maximum of 186 acres (75 ha) of habitat. Limited GPS re-surveys in 2004 suggest the true area of occupied habitat may be about half this amount. California calculated acreage in that state at approx. 150 acres in 2005.

Number of Occurrences: 6 - 20
Number of Occurrences Comments: Currently known from 6 extant populations in Washoe and Douglas Counties, Nevada, and 8 extant populations in Lassen, Plumas and Sierra Counties, California. This brings the total extant sites to about 14.

Population Size Comments: Population estimated to be at least 4,855,200 individuals. Note: These plants occur densely on ery limited acreage. May 2005 records from California indicate 112,500 plants there.

Number of Occurrences with Good Viability/Integrity: Few (4-12)
Viability/Integrity Comments: Globally about 6 occurrences are estimated to have good or excellent viability.

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: Threatened by residential development (especially in the Reno area), road development and maintenance, land conversion to agricultural uses, and off-road vehicle use, and also vulnerable to concentrated livestock trampling, fire suppression activities, and competition from invasive weeds. Transmission line development is considered a threat at two California occurrences.

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: The number of occurrences with good viability has declined recently due to encroachment of residential development and invasive plant species.

Long-term Trend: Decline of 30-50%
Long-term Trend Comments: The number of occurrences with good viability has likely declined at least 25% historically due to agricultural and grazing practices, development, and encroachment of invasive plant species.

Intrinsic Vulnerability Comments: No studies of reproduction or dispersal are known for Ivesia webberi. Insect-mediated out-crossing is the most likely reproductive mode. Seed dispersal for this species is probably low to none. The seeds are relatively large and probably become lodged in crevices in the rocky pavement-like soils very soon after being shed by the parent plant. No asexual or vegetative reproduction is apparent in this species. It can tolerate some moderate disturbance as it has been observed in some mildly disturbed sites; however long-term survival depends upon the continued availability of undisturbed mid-elevation benches or saddles with shallow, very rocky pavement-like soils derived from andesite or similar volcanic material.

Environmental Specificity: Narrow. Specialist or community with key requirements common.
Environmental Specificity Comments: While the habitat occupied by Ivesia webberi appears to be relatively common across its geographic range, the vast majority of apparently suitable habitat has proven to be unoccupied by the species, suggesting that more cryptic habitat factors may also be involved.

Other NatureServe Conservation Status Information

Distribution
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Global Range: Found in Sierra, Dog and Honey Lake Valleys, Sierra and Lassen Counties, Western Nevada and adjacent eastern California. Known from Upper Long Valley on the California-Nevada border, and elsewhere in Nevada from both north and southwest of Reno, Washoe County, and from the western slope of the Pine Nut Mountains, Douglas County. When the disjunct Douglas County, Nevada, occurrence is excluded, range extent decreases from about 1600 km2 to under 1000 km2. California drew a least square around the known occurrences in 2005 and estimated range size there as 2800 sq mi.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
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 Lassen (06035), Plumas (06063), Sierra (06091)
NV Douglas (32005), Washoe (32031)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Truckee (16050102)+, Upper Carson (16050201)+
18 East Branch North Fork Feather (18020122)+*, Middle Fork Feather (18020123)+, Honey-Eagle Lakes (18080003)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A perennial, tap-rooted low spreading herb to 2.5 dm across, hairy throughout; overall color greenish-gray foliage with dark red stems and bright-yellow clusters of flowers, the whole plant becoming reddish-tinged late in the season. Leaves 3-7 cm long, mostly basal, with 4-8 pairs of leaflets crowded toward tips; leaflets 3-10 mm long, each further divided into 2-5 narrow segments. Flower clusters at stem tips, about 15-50 mm across, with 5-15 flowers each; each flower about 10 mm across on a stalk 1-8 mm long, petals 5, bright yellow, 2-3 mm long, much smaller than the green sepals; stamens 5.

Terrestrial Habitat(s): Shrubland/chaparral
Habitat Comments: Shallow shrink-swell clay soils with a gravelly surface layer over volcanic, generally andesitic bedrock, on mid-elevation benches and flats at elevations of 1360-1820 m, usually codominating with Artemisia arbuscula and Elymus elymoides in association with Antennaria dimorpha, Balsamorhiza hookeri, Erigeron bloomeri, Lewisia rediviva, Viola beckwithii, etc. Ivesia webberi has been found only in relatively open plant associations where competition for light and moisture with other species is low. It is absent from adjacent, otherwise appropriate habitat where deeper soils and taller, denser vegetation has developed.

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
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Excellent Viability: SIZE: at least 4000 maximum detectable individuals occupying at least 4 ha of apparently suitable habitat. CONDITION: multiple age classes present in ratios appropriate to generation time of element. Evidence of flowering and fruiting, seedlings, or other indications that reproductive mechanisms are intact. Less than 5% cover of exotic plant species. Less than 5% cover of significant anthropogenic impacts. LANDSCAPE CONTEXT: Surrounding area is relatively unfragmented and includes the ecological processes needed to sustain the element and its habitat.
Good Viability: SIZE: at least 1000 maximum detectable individuals occupying at least 1 ha of apparently suitable habitat. CONDITION: multiple age classes present in ratios appropriate to generation time of element. Evidence of flowering and fruiting, seedlings, or other indications that reproductive mechanisms are intact. Less than 10% cover of exotic plant species. Less than 10% cover of significant anthropogenic impacts. LANDSCAPE CONTEXT: Surrounding area includes the ecological processes needed to sustain the element and its habitat, though it may be significantly fragmented, invaded by exotics, or otherwise impacted by humans.

Fair Viability: SIZE: at least 200 maximum detectable individuals occupying at least 0.2 ha of apparently suitable habitat. CONDITION: multiple age classes present, but often in ratios indicating reduced or irregular recruitment. Evidence of flowering and fruiting, seedlings, or other indications that reproductive mechanisms are intact. Up to 50% cover of exotic plant species and/or up to 50% cover of significant anthropogenic impacts. LANDSCAPE CONTEXT: Surrounding area may be heavily fragmented, disturbed, and/or invaded by exotics, but still includes the ecological processes needed to sustain the element and its habitat.

Poor Viability: SIZE: less than 200 maximum detectable individuals and/or less than 0.2 ha of apparently suitable habitat occupied. CONDITION: little or no evidence of successful or sustainable reproduction (poor age class distribution, no seedlings, and/or no evidence of flowering and fruiting, etc.). Cover of exotic plant species and/or significant anthropogenic impacts may exceed 50%. LANDSCAPE CONTEXT: Surrounding area may be heavily fragmented, disturbed, and/or invaded by exotics, with some or all ecological processes needed to sustain the element and its habitat no longer intact.

Justification: Existing EOs of this element likely include the best that will ever exist in the future, and only minor downward trends have yet been observed, so A-rank criteria are based on the sizes, conditions, and landscape contexts of the best 10% of existing occurrences. In general, population size (area of occupancy and abundance) is the primary factor influencing EO rank. Larger populations in higher quality sites are presumed to contain a higher degree of genetic variability, to have a lower susceptibility to the effects of inbreeding depression, and to be relatively resilient. Although no population viability data exist for this element, "D" ranked occurrences are estimated to have a very low probability of long-term persistence due to inbreeding depression, natural stochastic events, habitat degradation, and/or intrinsic vulnerability to human impacts. Because annual climatic variation results in wide natural fluctuations in numbers of detectable individuals of this element, population abundance of an EO is based on the maximum observed abundance at that site while in its current overall condition and landscape context, unless an overall downward trend in abundance is apparent at that site. Significant anthropogenic impacts are those that reduce population size and/or viability for at least the next 25 years unless restored.
Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
Date: 10Dec2004
Author: J. Morefield
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: 22May2006
NatureServe Conservation Status Factors Author: J. Morefield (NVHP), rev. R. Bittman 5/2005, rev. L. Morse (2005), rev. R. Bittman 2006

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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  • Abrams, L. 1944. Illustrated flora of the Pacific states: Washington, Oregon, and California. Vol. 2. Polygonaceae to Krameriaceae. Stanford, California: Stanford University Press. 635 pp.

  • Cronquist, A., N.H. Holmgren, and P.K. Holmgren. 1997. Intermountain flora vol. 3, part A. Subclass Rosidae (except Fabales). Bronx: The New York Botanical Garden. 446 pages.

  • Gray, A. 1874. Contributions to the botany of North America. Proceedings of the American Academy of Arts and Sciences 10: 39-78.

  • 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. 1986-present. Slide collection files. Carson City.

  • Nevada Natural Heritage Program. 1998-present. Index to available images (web page). Carson City: Nevada Natural Heritage Program public web site, http://heritage.nv.gov/images.htm.

  • Skinner, M.W., and B.M. Pavlik, eds. 1997 (1994). Inventory of rare and endangered vascular plants of California. 1997 Electronic Inventory Update of 1994 5th edition, California Native Plant Society, Special Publication No. 1, Sacramento.

  • U.S. Fish and Wildlife Service (USFWS). 2004. Species assessment and listing priority assignment form. Ivesia webberi. 12 pp.

  • U.S. Fish and Wildlife Service. 2013. 12-Month Finding and Candidate Removal for Potentilla basaltica; Proposed Threatened Species Status for Ivesia webberi. Federal Register 78(149): 46889-46897.

  • Whitham, C. W. 1991. Final report, focused field survey, Ivesia webberi, Webber's ivesia, Toiyabe National Forest, Sierra County, California and Washoe County, Nevada, June 3-27, 1991. Sparks: Toiyabe National Forest, unpublished.

  • Witham, C.W. 1999. Current knowledge and conservation status of Ivesia webberi Gray (Rosaceae), the Webber's Ivesia, in Nevada. Carson City: DRAFT Status report prepared for Nevada Natural Heritage Program and US Fish and Wildlife Service.

  • Witham, C.W. 2000. Current knowledge and conservation status of Ivesia webberi Gray (Rosaceae), the Webber ivesia, in Nevada. Carson City: Nevada Natural Heritage Program, status report prepared for the U. S. Fish and Wildlife Service, Reno, Nevada.

  • Witham, C.W. 2000b. Current knowledge and conservation status of Ivesia webberi Gray (Rosaceae), the Webber ivesia, in Nevada. Carson City: Nevada Natural Heritage Program, status report prepared for the U. S. Fish and Wildlife Service, Reno, Nevada.

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