Small to large epiphytic ferns (sometimes bracket-epiphytes) or rarely terrestrial ferns. Rhizome usually long-creeping, sometimes shortly creeping, clothed with hairs in 2 genera, otherwise bearing peltate-based, clathrate or non-clathrate scales which do not have stiff hairs, solenostelic or dictyostelic, often with black sclerenchymatous strands in the cortex. Stipes in 2 rows if the rhizome is creeping, generally articulated to the rhizome. Fronds uniform to very dimorphic; humus-collecting scale-leaves present in some genera. Lamina simple or lobed or pinnate or dichotomously branched, glabrous or often clothed with peltate scales or stellate hairs. Pinnae articulated or not articulated to the main rhachis. Veins mostly anastomosing with free vein-endings in the areolae (Fig. 18 & 19) or very rarely free, often ending in hydathodes. Sori exindusiate, round and superficial or immersed; borne either at the vein-junctions or on the free veinlets usually in the areolae; otherwise elongated and parallel to the main veins or to the margin; sometimes acrostichoid over the whole fertile surface or in portions specialized as fertile. Sporangia glabrous or rarely setulose; annulus interrupted or complete, composed of 12–14 (rarely up to 24) thick-walled cells, 5–10 thin-walled cells and a stomium which is 2-celled or rarely undifferentiated; pedicel with 2–4-rows of cells. Paraphyses absent or simple, more usually clathrate, umbrella-shaped, stellate or with swollen apices. Spores bilateral, monolete, mostly smooth or tuberculate, often hyaline, without a perispore. approx. 30 gen., mainly trop. to subtrop.