Plants perennial, terrestrial, on rock, or often epiphytic, erect, arching, or occasionally pendent. Stems long- to short-creeping, branched or not, bearing scales and few to numerous roots, usually dictyostelic. Leaves monomorphic to dimorphic, circinate in bud. Petiole usually articulate at base [rarely nonarticulate, as in Loxogramme ], lacking scales or sometimes scaly, with usually 3 vascular bundles. Bladesimple to often pinnatifid, pinnatisect, or pinnate, infrequently moredivided; rachis grooved or not adaxially. Veins free (and simpleto several times forked) to often anastomosing in complex systems, areoleswith or without included veinlets. Indument on blade absent, orpetiole, rachis, costae, and sometimes blade tissue usually bearing hairs(these often septate and with reddish crosswalls) and/or scales. Soriborne abaxially on veins, round to oblong, occasionally elongate, rarelymarginal, rarely covering surface; paraphyses present or absent; sporangiawith stalk of 2 or 3 rows of cells; indusia absent. Spores usuallytransparent or yellowish (rarely greenish), all 1 kind, bilateral, monolete[rarely trilete, as in some Loxogramme], surface most often smooth,tuberculate, verrucose, or granulate, occasionally spiny, 64 per sporangium(spores globose and 32 per sporangium in apogamous spp.). Gametophytesgreen, aboveground, cordate or elliptic, glabrous or sometimes glandular;archegonia and antheridia borne on lower surface, antheridia 3-celled.
Plants mostly epiphytic and epilithic, a few terrestrial. Rhizomes shortly to long creeping, dictyostelic, bearing scales. Fronds monomorphic or dimorphic, mostly simple to pinnatifid or 1-pinnate (uncommonly more divided); stipes cleanly abscising near their bases or not (most grammitids), leaving short phyllopodia; veins often anastomosing or reticulate, sometimes with included veinlets, or veins free (most grammitids); indument various, of scales, hairs, or glands. Sori abaxial (rarely marginal), orbicular to oblong or elliptic, occasionally elongate, or sporangia acrostichoid, sometimes deeply embedded, sori exindusiate, sometimes covered by caducous scales (soral paraphyses) when young; sporangia with 1-3-rowed, usually long stalks, frequently with paraphyses on sporangia or on receptacle; spores hyaline to yellowish, reniform, and monolete (non-grammitids), or greenish and globose-tetrahedral, trilete (most grammitids); perine various, usually thin, not strongly winged or cristate. Mostly x = 35, 36, 37.