Taxonomy remains uncertain. All records of nigra (sensu lato) from Ky. may be referable to var. radiata DC. (X moncktonii), which has been interpreted as derived from hybridization with jacea (FNA 19, Y, W).The first report of jacea from Ky. was in 1914, when Gm noted: "Not very common. Local. It has been accused of poisoning stock". He also reported nigra as "not common". His colls. (APSC, Ky.-Agr.) nay be referable to nigra var. radiata