Symphyotrichum rhiannon is a species of flowering plant endemic to a serpentine barren in western North Carolina.

[4] Symphyotrichum rhiannon is a perennial flowering plant that grows between heights of 15 and 60 centimeters (5.9 and 23.6 inches).

[4] Kauffman, Nesom, et al., formally explained the etymology of the species as follows:[4] [It] is named in honor of Rhiannon Weakley, whose desire to rest during a field excursion led the authors to further investigate..., and also in honor of the original Rhiannon, a Welsh goddess figure....

[8] "Rhiannon hadn’t had a nap that morning," says Alan Weakley, "and she had a little, ah, loss of composure."

Symphyotrichum rhiannon is endemic to the Buck Creek Serpentine Barrens in Clay County, North Carolina, in the Nantahala National Forest.