Sporophytes herbaceous, perennial, terrestrial or rarely epiphytic. Rhizome non-palaceous, mostly short, erect, unbranched, bearing thick, fleshy, hairless roots. Fronds erect or pendulous, 1–several; each composed of a common basal stalk, a sterile and a fertile segment; sterile lamina sessile or petiolate, simple, lobed, palmately or pinnately compound or decompound; veins free or anastomosing; fertile spike simple or paniculate, appearing to arise on the adaxial surface of the sterile blade but really lateral in origin; vernation straight or inclined, never circinnate. Sporangia in 2 marginal rows, free or coalescent, exindusiate, devoid of an annulus, globular, ovoid or hemispherical, sessile or with a very short pedicel; dehiscing horizontally or vertically into 2 valves. Spores very thick-walled, tetrahedral or bilateral, very numerous. 3 gen., mostly cosmop.