To confirm the taxonomic treatment of Megaleranthis saniculifolia Ohwi, an endemic genus and species in Korea, we compared its reproductive morphological characteristics with those of Trollius and other genera within the Ranunculaceae. Although its external morphology might suggest that Megaleranthis differs from Trollius, Calathodes, and etc., we found no distinctly different features in this genus. Likewise, previous studies of their pollen structures, chromosome data, and petal morphology have indicated no differences between Megaleranthis and Trollius. In fact, related genera share similar characteristics, such as a tetrasporangia anther, glandular tapetum, simultaneous cytokinesis, an anatropous and bitegmic ovule, embryo sac formation of the Polygonum type, exarillate and copious albuminous seed, and several apocarps. Although the unique feature of having both tenuinucellate and crassinucellate ovules simultaneously may initially seem particular to Megaleranthis, it is present in other genera of the same family. Therefore, based on this evidence of reproductive morphology and other information, we suggest that M. saniculifolia is closely related to Trollius, and should be included within that genus, i.e., as T. chosenensis Ohwi. Nevertheless, we have tentatively placed Megaleranthis within its own monotypic and endemic genus until definitive data become available.