2 gen., trop. to temp.Sporophytes terrestrial or epiphytic. Rhizomes creeping and branched, covered with fine brown rhizoids. Aerial axes erect or pendulous, rigid or flaccid, simple or branched dichotomously. Sterile lateral appendages undivided. Synangia composed of 2–3 (very rarely 4) fused sporangia, occurring singly in the axils of bifid or bifoliate appendages. Spores bilateral.