The first molecular phylogeny showed that "Osmunda" as traditionally circumscribed was paraphyletic and that "Osmunda cinnamomea", despite its morphological similarity to "Osmunda claytoniana", was sister to the rest of the family. This was later confirmed by a detailed species-level phylogeny of the family by Metzgar et al. (2008) leading to the resurrection of the segregate genus "Osmundastrum", by elevating it from subgenus, to contain it and render "Osmunda" monophyletic. "Todea" and "Leptopteris" are consistently resolved as sister groups, and "Osmunda" was found to contain three separate subclades corresponding to subgenera (now genera) "Osmunda", "Plenasium", and the recently described "Claytosmunda" with the single species, "Osmunda claytoniana".