flora of dolomite and limestone barrens in southwestern Virginia

The vegetation and flora of 16 dolomite and limestone barren sites in Lee and Russell Counties, Virginia are described. Two-hundred and ninety-eight native and 26 exotic taxa were recorded from the Virginia barrens. Families with the highest number of taxa are the Asteraceae (54 taxa, 16.7%), Poaceae (43 taxa, 13.3%), Fabaceae (19 taxa, 5.9%), and Cyperaceae (17 taxa, 5.6%). Five taxa, Aster pratensis, Carex crawei, Hedyotis nigricans, Rhamnus lanceolata ssp. glabrata, and Spiranthes magnicamporum are reported as new to Virginia, along with 14 others considered rare in the Commonwealth. When floristic similarity is calculated between study sites, barren sites within each county are more similar than Lee and Russell County sites are to each other. Virginia barrens are also compared floristically with other barrens in the Ridge and Valley Physiographic Province. Ecological maintenance of barren communities is attributed to drought stress in possible combination with other factors, including fire. Use of the term barren, glade, and prairie to name this vegetation is discussed.