|McDonald's rock cress, Red Mountain rock cress|
|Edward Guerrant, Ph.D.|
The following Participating Institutions are custodians for this species in the CPC National Collection:
Rae Selling Berry Seed Bank & Plant Conservation Programs
The conservation of Arabis mcdonaldiana is fully sponsored.
Edward Guerrant, Ph.D. contributed to this Plant Profile.
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.
Distribution & Occurrence
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%.
Ranges: CA: NcoRO (Klamath -Siskiyou Region)
OR: Klamath Mountains
|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.|
Conservation, Ecology & Research
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.
Proposed construction and mining for nickel (Nicore Corporation) 1997/98/99
Over-collection (Meinke 1982)
Off-road vehicle use
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).
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.
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).
Determine propagation and reintroduction protocols.
Meinke, R.J. 1982. Threatened and Endangered Vascular Plants of Oregon: An Illustrated Guide. Portland, Oregon: U.S. Fish & Wildlife Service, Region 1. 326p.