The gametophyte development of Lomagramma sorbifolia (Willd.) Ching has been studied. Spore germination is of the polar and Vittaria-type. Prothallial development is either of the Adiantum-type, or more rarely of the Drynaria-type. This Adiantum-type is unusual among most of the other genera of the lomariopsidoid ferns. The Drynaria-type of gametophyte development is more characteristic of the lomariopsidoid ferns. Older prothalli are cordate and naked throughout. Early development seems to be somewhat plastic and perhaps of limited usefulness as a character for systematic purposes.