Helianthus eggertii Small is a little known rare species closely associated with the Interior Low Plateaus Province. It is a distinct hexaploid species closely allied with Helianthus strumosus L., from which it can be distinguished by its blue-glaucous shoots with leaves glabrous, sessile, and single-veined. The taxon has been documented in 13 counties, with most of the 26 known populations clustered in just three physiographic regions in Kentucky and Tennessee; 20 of these populations are newly located. Less than half of the known sites contain large, reproducing populations. The primary habitats are open barrens or open oak-hickory woodlands with a high species richness of native associates. The populations occur on rolling to flat topography, on well drained, shallow, acidic soils, over a substrate of Mississippian limestones. In most populations, the seed set is moderate, but the principle means of reproduction appears to be by an extensive rhizome system. The primary threat to this species appears to be loss of the “barrens” habitats through removal of fire and subsequent competition and succession.