The floristic ecology of xeric limestone prairies in Kentucky, and a comparison to limestone cedar glades and deep-soil barrens

The flora of 18 xeric limestone prairies in the Interior Low Plateaus physiographic province in Kentucky was surveyed and a checklist of vascular plants prepared for each site. Nine of the 18 sites are in the Knobstone Escarpment and Knobs, four in the Mammoth Cave Plateau, two in the Pennyroyal Plain and three in the Outer Blue Grass. Life form, photosynthetic pathway, geographic affinity, conservation status and presence were determined for each taxon. Community coefficients were calculated from site floristic lists, and the physiography, geology and soils associated with each site were documented. The flora of xeric limestone prairies in Kentucky was compared to that of limestone cedar glades of the southeastern United States and of deep-soil barrens of the southwestern Pennyroyal Plain in Kentucky and Tennessee. Three hundred and thirty-five taxa were identified in this plant community type, of which 20 are nonnative and 24 state-listed. Families with the highest number of taxa were Asteraceae (70), Poaceae (32) and Fabaceae (29); genera with the highest number of taxa were Symphyotrichum (15), Panicum sensu lato (=Panicum + Dichanthelium) (10), Carex (7), Solidago (7) and Hypericum (6). Intraneous C₃ hemicryptophytes make up the majority of the flora. Community coefficients indicate high similarity among all sites except those in the eastern outer Blue Grass, which belong to a second association or community type. Endemic species, a higher percentage of therophytes (i.e. annuals, especially winter annuals) and a higher number of taxa with western and northwestern geographic affinities distinguish the limestone cedar glade flora from those of xeric limestone prairies and deep-soil barrens.