Plants terrestrial, sometimes epipetric or rheophytic, rarely scandent (Thelypteris subg. Amauropelta sect. Lepidoneuron A.R. Sm.); roots blackish, wiry, inserted  radially, non-proliferous; rhizomes not usually branched, short to long-creeping, suberect, or erect, rarely sub-arborescent, bearing scales; rhizome scales lanceolate, non-clathrate, grayish to tan or brown, entire or dentate, the margins and often the surfaces usually bearing distinct pubescence similar to that of the leaves; leaves usually greenish in all stages, occasionally reddish when young (e.g., some Cyclosorus species treated in Mesophlebion and Pronephrium, possibly others), sometimes covered in mucilage when young, usually monomorphic, sometimes sub-dimorphic, spirally arranged, closely to distantly spaced, occasionally bulbiferous, the bulbils usually distal or apical on the leaf, scaly or not, almost always pubescent, the hairs whitish or hyaline, acicular, or sometimes forked, stellate, stalked-stellate, or hamate, also often provided with sessile or stalked glands; petioles greenish to stramineous, sometimes darker, the bases not articulate to the rhizome, not expanded at the base, and generally not persistent on the rhizome; petiole vascular bundles two vascular bundles (rarely more), with hippocampiform-shaped xylem, distally uniting to form a single U-shaped bundle; laminae thin-herbaceous to coriaceous, simple and entire to 3-pinnate-pinnatifid, in divided leaves, the base with or without a series of reduced pinnae, the apex conform or non-conform, the leaf marginal cells not clearly differentiated; pinna axes not articulate, the pinna base often with a conspicuous aerophore, these  usually appearing as a low elongate or orbicular protuberance, or erect and vermiform, up to ca. 1 cm long; rachis axes sulcate adaxially or not, when present the sulcae not continuous onto the next order, lacking a free central ridge; veins reaching the leaf margin or terminating before it, free, connivent at or below the sinus in lobed pinnae, or anastomosing in various patterns, the areoles without free included veinlets, the vein endings expanded or not differentiated; sori circular or elongate, on top of veins, not terminal, indusiate or exindusiate; soral receptacle flat; indusia lateral, reniform, sometimes  pubescent and or glandular; sporangia with stalks more than one cell wide in the middle, often bearing hairs or glands (paraphysate); spores usually monolete, sometimes trilete (Cyclosorus treated as Trigonospora), nonchlorophyllous, the perispore brown, often with sharp crests, or reticulate or  echinulate; chromosome base numbers x = 27 (e.g., Parathelypteris; Weng & Qiu, 1988), 29 (e.g., Amauropelta; Walker, 1985), 30 (e.g., Phegopteris;  Mitui, 1975), 31 (e.g., Lastrea, Macrothelypteris, Pseudophegopteris, Wagneriopteris; Mitui, 1975; Loyal, 1991; Tindale & Roy, 2002), 34 (e.g., Oreopteris; Holttum, 1981; Manton, 1950), 35 (e.g., Metathelypteris, Pseudocyclosorus, Thelypteris; Mitui, 1975; Loyal, 1991; Walker, 1985), or 36 (e.g., Abacopteris,  Ampelopteris, Amphineuron, Christella, Cyclogramma, Cyclosorus, Dictyocline, Goniopteris, Lastrea, Leptogramma, Meniscium, Pronephrium, Stenogramma; Mitui, 1975; Walker, 1985; Loyal, 1991; Tindale & Roy, 2002).

The family Thelypteridaceae as interpreted here includes about 950 species distributed among five genera, based on recent study. In the past, up to 24 additional genera have been recognized. Despite is large size, members of the Thelypteridaceae can usually be recognized by the presence of distinctive acicular hairs. These hairs are whitish or hyaline, and usually 1-celled. In addition to being on the leaves, these hairs also regularly occur upon the margins and faces of the rhizome scales. While dentate or ciliate scales are common, as far as we know, no other family in Eupolypods II has rhizome scales that bear hairs similar to those found upon the leaves. Hamate, forked, and stellate hairs also occur in Thelypteridaceae, which being uncommon in Eupolypods, are also useful diagnostic characters. Thelypteridaceae also frequently have conspicuous aerophores at the bases of their pinnae. These often differ in color and texture from the  surrounding tissue, and are frequently raised. In some cases, elongate vermiform aerophores are present; these frequently occur in species in which the crosiers and young leaves are surrounded by thick mucilage.