This occurs mostly in the central and lower Mississippi watershed plus the Gulf Coastal Plain. It extends north to n. Mo., c. Ill., c. Ind. and n. Ohio (K). There are few Ky. records, mostly from thin mesic to subhydric woods and edges on terraces of rivers in western regions, but the species is locally frequent (M). It is close to I. hexagona Walt., which is known only from S.C. and Fla. (FNA 26). A coll. of hexagona by R. Peter (PH) has been attributed to Ky., but there are no locality data and it may have come from interstate exchange (M).