Rhizome long creeping, solenostelic or protostelic, covered with bristles or articulate hairs. Stipe with a single vascular bundle proximally and polystelic distally; lamina (sterile ones, at least) cleft into 2 or often more subequal parts; veins highly reticulate, with included veinlets. Sori exindusiate, discrete, compital (at intersection of connecting veins), scattered over surface, or fronds dimorphic and fertile ones covered with sporangia; sporangia maturing simultaneously or maturation mixed, with 4-seriate stalks; annuli almost vertical or slightly oblique; spores ellipsoid and monolete, or tetrahedral and trilete, surface smooth or rugulose, ca. 64 or ca. 128 per sporangium; gametophytes cordate-thalloid. x = 33.