Herbs, epilithic, epiphytic, or terrestrial. Rhizome dorsiventral, thin, up to ca. 5 mm in diam., widely creeping, with clathrate scales. Fronds herbaceous, remote; stipe usually shiny and castaneous to dark purplish or black, rarely grayish green, semiterete abaxially, sulcate adaxially; lamina 1-pinnate, rarely simple; rachis sulcate adaxially, basiscopic margin of pinnae often decurrent and forming narrow abaxial wings on rachis; pinnae asymmetrical with basal basiscopic part cut away and becoming dimidiate; basiscopic margin entire, acroscopic margin crenate, undulate, or serrate, sometimes with retuse teeth. Veins free, rarely anastomosing, anadromously branching, becoming simple toward pinna apex, not reaching margin, 1 to several basal basiscopic veins lacking. Sori solitary, rarely double, linear to subelliptic, indusiate; indusium thinly membranous to papery, free margin entire to erose; stalks of sporangia long uniseriate, annuli of 20-28 hardened cells. Spores bilateral, elliptic, perispore elaborate, exospore smooth; in sexual plants 64 spores per sporangium. Plants sexual or agamosporous. x = (36), 38, 39.