This southeastern species is closely related to the less robust glaucodea, and there may be some intergradation (FNA 20); some authors have combined these taxa (e.g. Cr). In Ky. there are only a few verified records of flaccosperma, all from western lowlands. Several previous records from the state are referable to glaucodea (M). C. flaccosperma is best distinguished from glaucodea by its achenes, with bodies only 37-50% as long as perigynia (versus 50-67%), and beaks straight to bent less than 30 degrees (versus bent 30-90 degrees). Both species have distinctively glaucous leaves, but those of flaccosperma tend to be broader (mostly 7-14 mm versus 6-10 mm).