Sori superficial, dorsal. Indusium either complete, globose, at first covering sorus, finally splitting into lobes; or incomplete, never covering sorus, or vestigial, or absent. Sporangia small, shortly stalked, attached to short or elongate receptacle, often with paraphyses; maturation gradate. Annulus complete, oblique, with definite stomium, dehiscence by lateral slit. Spores 64, tetrahedral, without perispore. Caudex well-developed, dictyostelic. Paleae present, hairs present or not. Fronds us. very large, pinnately compound, mostly coriac.; veins free. Tree ferns of tropical and temperate regions.