The vascular flora of Estill County, Kentucky, U.S.A.

The vascular flora of Estill County, Kentucky was investigated during four growing seasons in 1987, 1988, 1989, and 2022. This study documented a total of 963 vascular plant species (773 herbaceous, 190 woody), representing 479 genera and 134 families. Numbers of taxa by major plant groups were fern and fern allies (42), gymnosperms (6), basal angiosperms (1), magnoliidae (10), monocots (244), and eudicots (660). This Estill County flora represents 33.2% of the known vascular plants of Kentucky. Families with the largest numbers of taxa were Asteraceae (126), Poaceae (109), Cyperaceae (61), Fabaceae (49), Lamiaceae (36), Rosaceae (35), and Apiaceae (20). These seven families represent 45.2% of the total flora. The largest genus was Carex (40), followed by Solidago (17), Dichanthelium (15), Quercus (14), Symphyotrichum (13), and Viola (12). Quercus (14) was the largest woody genus. Non-native species (153) comprised 15.9% of the flora. Eighty-two are listed by the Kentucky Invasive Plant Council, with 27 categorized as a “Severe Threat.” Twenty-three plants are listed as Endangered (7), Threatened (6), Special Concern (10), or Commercially Exploited (1). Two state records and a third county record were documented. Ten significant locations are described on the basis of field observations and plant sampling. Habitats included mesophytic ravines, limestone outcrops, cliffs, and ridgetops, ruderal/disturbed areas, marshy areas, swamps, oak-hickory forests, shorelines of ponds, creeks, streams and rivers, roadsides, xeric ridgetops, pine forests, railroad tracks, sandstone ridgetops and cliffs, and dry shaly areas. The species richness of Estill County averages 1.5 species per ha. It has the third highest number of documented taxa for a single Kentucky county.