ABSTRACT
Terrestrial or epiphytic herbs, erect or prostrate to pendulous or climbing. Stems usually branching dichotomously. Leaves simple, arranged in spirals or whorls, isophyllous or not with one distinct or obscure simple vein or midrib. Sporophylls similar to foliage leaves and generally intermixed with them to wards end of otherwise sterile branches, or modified, reduced in size and aggregated at ends of branches into obvious strobili. Sporangia solitary either in axils of leaves or on upper surface at base of sporophyll, unilocular, compressed-subglobose or reniform., shortly stalked or subsessile, transversely dehiscent into two valves. Spores isosporous, achlorophyllous, subglobose to tetrahedral, with trilete scar. Prothalli where known, monoecious, green, tu berous, subterranean or living on soil surface.
