Rock Gnome Lichen (Gymnoderma lineare)
Family: Cladonia (Cladoniaceae)
Federal Status: Endangered, listed January 18, 1995
Best Search Time: Year-round
Description: One of two lichens on the federal list of threatened and endangered species, Rock gnome lichen is the only member of the genus Gymnodera to live in North America. Other members of this genus live in the mountains of east Asia, including Japan and the Himalayas. Rock gnome lichen occurs in dense colonies of narrow strap-like lobes that are about 0.04 inch (1 millimeter) across and generally one to two centimeters long. These lobes are blue gray on the terminal upper surface, and generally shiny white on the lower surface, grading to black near the base. The fruiting bodies are born on the tips of these lobes, are black, and have been found from July through September. The primary means of propagation appears to be asexual, with colonies spreading clonally.
Habitat: Rock gnome lichen is primarily limited to vertical rock faces where seepage water from forest soils above flows during (and only during) very wet times. It appears the species needs a moderate amount of light, but that it cannot tolerate high-intensity solar radiation. It does well on moist, generally open, sites, with northern exposures, but needs at least partial canopy coverage where the aspect is southern or western.
Distribution: Rock gnome lichen is known from the Southern Appalachian Mountains of North Carolina and South Carolina, Tennessee, and Georgia, in areas of high humidity, either at high elevations, where it is frequently bathed in fog, or in deep gorges at lower elevations.
Threats: Rock gnome lichen is found at locations that often coincide with popular recreational destinations, one of the greatest threats to the rock gnome lichen is trampling and associated soil erosion and compaction from hikers, climbers and sightseers. The areas where the lichen is found, both at high elevation, and along streams, are both threatened by invasive insects. At high elevations, the balsam woolly adelgid, an Asian insect, attacks and kills Fraser fir trees; while in streamside areas, the hemlock woolly adelgid attacks and kills hemlock trees, a key riparian tree species. The removal of these trees could diminish the amount of shade on lichen sites, exposing the lichen to excess sunlight. Other threats include recreational and residential development, collection, and air pollution.
References:Buchanan, M.F. and J.T. Finnegan. 2010. Natural Heritage Program List of the Rare Plant Species of North Carolina. N.C. Natural Heritage Program, Raleigh, NC.
U.S. Fish and Wildlife Service. 1997. Recovery Plan for Rock Gnome Lichen (Gymnoderma lineare) (Evans) Yoshimura and Sharp. Atlanta, GA. 30 pp.
For More Information on Rock Gnome Lichen...
- U.S. Fish and Wildlife Service Environmental Conservation Online System
- Rock Gnome Lichen Recovery Plan
- U.S. Department of Agriculture Natural Resource Conservation Service Plants Database
- Center for Plant Conservation species profile
Mara Alexander, Fish and Wildlife Biologist, 828-258-3939 ext. 238
Species profile revised on September 15, 2011.