The Tennessee Purple Coneflower [Echinacea pallida (Nutt.) Nutt. var. tennesseensis (Beadle) Binns, B.R.Baum & Arnason], (Asteraceae, Binns et al. 2002) is a critically endangered and Federally listed coneflower known to occur in only three counties in the Nashville Basin, middle Tennessee (United States Fish and Wildlife Service 1989, Walck et al. 2002). Populations of Tennessee purple coneflower occur in cedar glades, barrens, and closely associated prairie or cedar woodland communities (Baskin and Baskin 1999, Drew 1991, Walck et al. 2002). Anthesis in E. pallida var. tennesseensis is mid-May to October, with a peak in June–July (Baskin and Baskin 1982, Walck et al. 2002).
We found newly emerged flowers on Tennessee coneflowers at a cedar glade in Wilson County, Tennessee, on 9 November 2007 (Figure 1). There had been below freezing temperatures and frost on 7 November (low 22uC, Dew Point 22uC), 8 November (low 0uC, Dew Point 21uC) and 9 November (low 3uC, Dew Point 4uC), but plants showed no damage. Other plants at the site, such as Allium cernuum Roth, Aster paludosus Aiton, Carex spp., Grindelia lanceolata Nutt., and Eupatorium altissium L., had some damage by frost. Rains had occurred on 8 November and daytime temperatures had reached 15 C…