Platyzoma-A Queensland Fern with Incipient Heterospory

First record is made of a dioecious condition in the heterosporous, terrestrial fern Platyzoma microphyllum R. Br. from northern Australia. The spores, gametophytes and young sporophyte are described and the role of heterospory and dioecism in these plants is discussed. The genus is newly classified as a subfamily Platyzomatoideae in the Polypodiaceae.