All the taxa of the genus Homaliadelphus, which exhibits geographic disjunction between eastern North America and eastern Asia, were investigated taxonomically. The following new combinations were made: Homaliadelphus laevidentatus (Okam.) and H. sharpii var. rotundatus (Noguchi). The var. laevidentatus was raised to specific rank as a result of dwarf male plants being found on leaves of female plants and for other reasons, as well. It is suggested that the genus may be a relict of an old tropical element which now has a scattered distribution in temperate regions of eastern Asia and North America.