Silphium integrifolium Michaux var. gattingeri L.M. Perry. Phen: Jul-Sep. Hab: Prairies and woodland openings. Dist: KY, MS, and TN.
Origin/Endemic status: Endemic
Taxonomy Comments: This variety appears to be morphologically intermediate between S. integrifolium var. integrifolium and S. asteriscus var. latifolium, and may have risen from the result of hybridization. It is found in a region at the western border of the range of S. asteriscus var. latifolium, mostly in the Western Highland Rim of Tennessee and in western Kentucky. In this region it forms distinctive populations, with the absence of either putative parent species. It is unclear what level of taxonomic rank, if any, is warranted.
Synonymy: = K1, Perry (1937); < Silphium asteriscus L. var. asteriscus – K4; < Silphium integrifolium Michx. var. integrifolium – F; < Silphium integrifolium Michx. var. laeve – C, FNA21