Numer. List. 1. 1829.
Plants terrestrial. Roots dark, fibrous, covered with dark, stiff hairs, 2–3 mm. Stems upright; hairs uniseriate. Leaves all fertile (even youngest), unbranched, long-petioled. Blades falsely digitate, reduced to 2–many erect to spreading terminal rays; rays appearing to be whorled but actually borne on very short rachis. Sporangia in 2–4 rows. Gametophytes subterranean, not green, tuberlike, brown-hairy. x = 134, 140.
Nearly worldwide in tropical regions.
Species 20 (1 in the flora).