Symphyotrichum rhiannon

Symphyotrichum rhiannon is a perennial herb endemic to North Carolina, U.S.A. It is known from a single occurrence within a critically imperiled (G1) serpentine plant community found in a small area surrounding Buck Creek in the southern Nantahala Mountains of Clay County, North Carolina. Serpentine soils in the Southern Appalachian Mountains are very rare, and only a few serpentine barrens have been located and studied. There is little or no potential for the discovery of additional occurrences. The species' habitat appears to be relatively stable since its discovery and with ongoing active management of woody vegetation at the site through prescribed burns habitat quality has improved. Feral hogs have been found in the serpentine barrens and cause damage to plants and habitat; if they are not successfully removed, they will continue to cause declines in habitat quality and population size.

Symphyotrichum rhiannon occurs in the eastern United States in North Carolina. It has only been documented from a Southern Appalachian outcrop barren within a serpentine plant community endemic to Buck Creek in the southern Nantahala Mountains of Clay County.

This species is known from a single occurrence, also the type locality.

Initially in response to periodic mining threats in the 1980’s and with further info on the rarity of the habitat including endemic species, 543 hectares, including the entire delineated serpentine site at Buck Creek, are now managed by the USFS as a Special Interest Area (USDA 2023). The entire site will be registered in a Natural Heritage Area with the North Carolina Natural Heritage Program. In 1995, the U.S. Forest Service initiated active conservation management of the site, using prescribed fire as the primary tool, resulting in reduction of woody growth encroaching on the site and an increase in herbaceous cover, particularly the grasses once dominant at the site (Kauffman et al. 2004). The rare flora depend on both fire and soil chemistry. Fire suppression reduces the success of the rare species associated with Buck Creek due to woody plants becoming denser and shading out the rare plants. The introduction of systematic burning has reduced canopy individuals and led to the increased presence of rare and endemic species within the research plots (Marx 2007).

The hard rock mineral lease for olivine is across 60 hectares, a portion of which is occupied habitat. The lease has been held since 1981 with BLM renewing it in 2007. This threat may be low but would require NEPA to ensure it does not happen (G. Kauffman, pers. comm., 2024).

Non-native invasive plants are not abundant in the area, possibly due to harsh soil conditions. However, non-native, feral hogs are a problem. The USFS is currently working with APHIS to remove individuals. Scattered damage is currently evident across the barren (G. Kauffman, pers. comm., 2024).