Vascular Flora and Biogeographic Affinity of the Sevier Shale Knobs of Northeastern Tennessee

ABSTRACT In the Ridge and Valley physiographic province, knobs stand out as anomalous landforms embedded within a region of long, parallel ridges and valleys. In northeastern Tennessee, knobs are associated with the Sevier shale. Well-drained, acidic, channery loam Montevallo soils cover uplands of these knobs. A flora of the Sevier shale knobs of northeastern Tennessee identified 265 taxa in 57 plant families of which 13.6% were exotic and three were state listed (Berberis canadensis, Ruellia purshiana, Silene caroliniana var. pensylvanica). Many taxa had rarely or never been collected in northeastern Tennessee. The flora of the Sevier shale knobs was most similar to dolomite and limestone barrens of southwestern Virginia but among the species rarely collected in northeastern Tennessee, the greatest number was shared with floras of the Sequatchie Valley, middle Tennessee cedar glades, and barrens of the Tennessee eastern Highland Rim.