CPC Plant Profile: Red Mountain Rockcress
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Plant Profile

Red Mountain Rockcress (Arabis mcdonaldiana)

Arabis macdonaldiana in bloom. Photo Credit: Veva Stansell
Description
  • Global Rank: G3 - Vulnerable
  • Legal Status: Federally Endangered
  • Family: Brassicaceae
  • State: CA, OR
  • Nature Serve ID: 132067
  • Date Inducted in National Collection: 03/14/1986

The small crimson to purple flowers of Arabis macdonaldiana are both beautiful and fragrant (Eastwood 1903). This interesting little plant was discovered in northern Mendocino County, California in 1902, and described as a distinct species the following year. Its discoverer was Alice Eastwood, one of the earliest and most well known female botanists. It was not identified in Oregon until 1980, a year after its listing as endangered with the Fish and Wildlife Service (Meinke 1982). Arabis macdonaldiana was the second plant species to be listed as endangered by the US Fish and Wildlife Service (September 1978). As the time of listing, only one population of A. macdonaldiana was known, and it was in imminent danger of being destroyed by nickel mining. Today, because of the discovery of additional populations in California and Oregon as well as some complex taxonomic changes, there are many populations of A. macdonaldiana known. Despite the fact that there are many more populations known than when it was originally listed, the species is still in grave danger. The large number of populations may make the species eligible for down-listing or de-listing. This may sound like a great accomplishment. However, populations are still small and still at great risk from mining activities and other human caused disturbances. As many of the known sites are on National Forest land, their listing as Endangered by the Fish and Wildlife Service is one of few protective measures keeping nickel mining from destroying them and their habitat.

Participating Institutions
Updates
  • 08/18/2020
  • Genetic Research

Taxonomic studies to investigate the relationship between California and Oregon populations. Results not published as of 2001 (Linda Ann Vorobik-UC Berkeley).

  • 08/18/2020
  • Propagation Research

Germination studies at the Berry Botanic Garden. Both 8 weeks of cold stratification followed by 68F (20C) and direct 68F (20C) treatments resulted in 100% germination (BBG file).

  • 08/18/2020
  • Orthodox Seed Banking

Seeds stored in BBG seed bank from collections in 1987 and 1989. All collections are from Mendocino and Del Norte Counties in California. No seeds are stored from Oregon populations. All collections are bulked- there is no separation of maternal lines (BBG File)

  • 08/18/2020
  • Seed Collection

Seeds stored in BBG seed bank from collections in 1987 and 1989. All collections are from Mendocino and Del Norte Counties in California. No seeds are stored from Oregon populations. All collections are bulked- there is no separation of maternal lines (BBG File)

Nature Serve Biotics
  • 05/02/2017

Restricted to serpentine areas and known from 30-40 sites in northern California (Mendocino, Del Norte and Siskiyou counties) and immediately adjacent southwestern Oregon. Some populations are threatened by mining of the nickel-rich soils of its habitat and encroachment of woody vegetation. Many sites are on USFS lands, but none may be in permanent protection.

Edward Guerrant, Ph.D.
  • 01/01/2010

Slope erosion, road maintenance, and logging. Succession Proposed construction and mining for nickel (Nicore Corporation) 1997/98/99 Over-collection (Meinke 1982) Off-road vehicle use

Edward Guerrant, Ph.D.
  • 01/01/2010

In Oregon, 2() extant populations with few individuals (ONHDB 2000). In California, 29 sites ""presumed extant"" with numbers ranging from ""a few"" to approximately 5,000 (CNDDB 2000). Many sites have not been surveyed since the mid 1980's, so numbers may not be accurate, and many sites that were reported as declining may in fact have been extirpated by now.

Edward Guerrant, Ph.D.
  • 01/01/2010

Germination studies at the Berry Botanic Garden. Both 8 weeks of cold stratification followed by 68F (20C) and direct 68F (20C) treatments resulted in 100% germination (BBG file). Taxonomic studies to investigate the relationship between California and Oregon populations. Results not published as of 2001 (Linda Ann Vorobik-UC Berkeley). Determination and search for potential habitat using Landsat Thematic Mapper imagery to locate serpentine barren habitat (Daniel and Fox 1999).

Edward Guerrant, Ph.D.
  • 01/01/2010

One population is located on land designated as a ""Botanical Wayside"". The area was established in 1938 to serve as an interpretive and educational resource for local agencies, organizations, and schools (CaveJunction.Com 2002). Seeds stored in BBG seed bank from collections in 1987 and 1989. All collections are from Mendocino and Del Norte Counties in California. No seeds are stored from Oregon populations. All collections are bulked- there is no separation of maternal lines (BBG File) Known Oregon sites are on National Forest Land.

Edward Guerrant, Ph.D.
  • 01/01/2010

Search for additional populations in Oregon and California (Meinke 1982) Protect any newly discovered populations (Meinke 1982) Limit land access and use (Daniel and Fox 1999). Determine soil variables associated with A. macdonaldiana presence (Daniel and Fox 1999) Determine how variables such as percent moss cover, percent rock, or microposition are correlated to species' occurrence (Daniel and Fox 1999). Determine how tree, shrub, herb or grass cover correlate with presence of species (Daniel and Fox 1999).

Edward Guerrant, Ph.D.
  • 01/01/2010

Collect and store seeds from representative populations in both Oregon and California. Keep maternal lines separate during collection. Determine propagation and reintroduction protocols.

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Photos
Nomenclature
Taxon Arabis mcdonaldiana
Authority Eastw.
Family Brassicaceae
CPC Number 182
ITIS 823056
USDA ARMA33
Common Names McDonald's rock cress | Red Mountain rock cress
Associated Scientific Names Arabis mcdonaldiana | Arabis serpentinicola | Arabis blepharophylla var. macdonaldiana | Arabis blepharophylla var. mcdonaldiana | Arabis macdonaldiana (a common misspelling)
Distribution CA, ORRanges: CA: NcoRO (Klamath -Siskiyou Region)OR: Klamath Mountains
State Rank
State State Rank
California S3
Oregon S1
Habitat

Serpentine barren habitat, usually on steep unstable slopes or dry open woods below 4900 ft (1500m). Most areas are recently disturbed, exposing less weathered serpentine soil. Canopy cover is generally less than 3%.

Ecological Relationships

Arabis macdonaldiana is found primarily on serpentine soils, which are high in many toxic metals, including: copper, chromium and nickel. It may thrive in these areas because of the limited competition that this harsh environment offers, or it may be adapted to the soil chemistry of the freshly exposed serpentine soil (Daniel and Fox, 1999). Arabis macdonaldiana is found on newly exposed serpentine soil as opposed to soil that has had time to weather.Serpentine barren habitat supports a great variety of endemic plants, many of which are sensitive or rare (in Daniel and Fox 1999). Serpentine soil is also heavily mined because of high concentrations of useful metals. Mining doesn't just destroy the land and the plants that inhabit the land. Due to the looming threat of a mining project, American Rivers has named Rough and Ready Creek to the list of North America's Most Threatened and Endangered Rivers.

Pollinators
Common Name Name in Text Association Type Source InteractionID

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