Plants terrestrial. Stems subterranean, protostelic; indument of dark, dense hairs. Leaves vinelike, of indeterminate growth. Pinnae reduced to short stalks, each bearing a pair of opposite pinnules, usually with an often dormant apical bud. Sporangia in 2 rows, 1 on each side of midvein of contracted, oblong, marginal lobes of ultimate segments, covered by hoodlike flap of tissue serving as indusium. Spores tetrahedral-globose, trilete, rarely monolete. Gametophytes terrestrial, cordate, glabrous.
Plants terrestrial. Stems branched, slender; fronds often more than several meters, alternately pinnate, climbing by means of a twining rachis; primary blade divisions (pinnae) pseudodichotomously forking with a dormant apical bud in axils; pinnules entire to palmately or 1- or 2-pinnate or more divided; fertile and sterile pinnae similar or fertile pinnae greatly contracted; veins free or anastomosing; sori on lobes of ultimate segments; sporangia abaxial, solitary, 1 per sorus, each sporangium covered by an antrorse indusium-like subtending flange; spores 128-256 per sporangium, tetrahedral and trilete; gametophytes green, cordate, terrestrial. x = 29, 30.