Thalli erect, attached by matted, branched rhizoids, up to 30 cm long, complanate, flabellate or lacerate with many elongate, cuneate branches, 0.5-6 cm broad, often tapering to the apex. Growth initiated from a marginal row of apical cells. Thallus 2 cells thick near apex increasing to 5-7 cells thick towards the thallus base, not arranged in rows in transverse section. Hairs in concentric lines across the thallus. Sporangia solitary, in irregularly scattered groups or in short concentric zones adjacent to the hair lines, partially embedded in or completely external to the frond, without a stalk cell or with 1-3 stalk cells, 80-140 mm high when mature, producing 4 spores. Gametophytes dioecious. Antheridial sori whitish, irregularly shaped, scattered over both thallus surfaces, 100-800 mm across, bounded by 1-2 layers of sterile cells. Antheridia with 15-20 tiers of locules, with one stalk cell. Oogonial plants unknown.