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.
Tropical regions nearly worldwide and temperate regions of North America and Asia, s Africa, Pacific Islands in New Zealand.
Genus 1, species ca. 40 (3 species in the flora).