Plants terrestrial or on rocks. Rhizomes stout, dictyostele radially symmetrical, branched or not, erect, ascending, or long creeping, with scales at apices; scales basiflexed, lanceolate or nearly ovate, brown, thick, luminae elongate, usually with grayish white short setae on dorsal side or ciliate along margins. Fronds clustered, approximate, or remote; stipes slender, stramineous, not articulate, with 2 crescent-shaped vascular bundles at base, usually scaly at bases, distally ± with grayish white unicellular acicular hairs, rarely with multicellular long hairs or stellate hairs. Fronds monomorphic, rarely subdimorphic, oblong-lanceolate or oblanceolate, sometimes ovate or ovate-triangular, usually pinnate-pinnatifid, sometimes 3- or 4-pinnate-pinnatifid, rarely 1-pinnate; pinnae symmetrical at bases; costae grooved adaxially but grooves not confluent with rachial grooves, or raised and with dense grayish acicular hairs, with expanded tuberculate aerophores at bases of pinnae. Laminae herbaceous or papery, sometimes somewhat leathery, green or dark brown-green when dry, both sides (particularly rachises, costae, and main veins adaxially) with grayish white unicellular acicular hairs, rarely glabrous, usually with orange or reddish orange, stalked or sessile spherical or club-shaped glands, occasionally small scaly along rachises and costae abaxially. Sori orbicular, oblong, or shortly linear, dorsifixed on veins, indusiate or exindusiate; indusia orbicular-reniform, fixed by deep notch, most ± hairy, persistent or hidden in sori, caducous, or not concentrated into sori but scattered along reticulate veins and exindusiate. Sporangia long stalked, usually with hairs or glandular hairs below annuli and at distal end of sporangial stalks. Spores bilateral, rarely tetrahedral, tuberculate, echinate, granular, or usually with a winged perispore. Prothalli green, cordate or narrowly cordate, usually with broad wings, symmetrical, usually with hairs or glands. x = 27-36 (lacking 28).
About 20 genera and ca. 1,000 species, more at lower elevations, very few tropical species above 4500 m: widespread in all tropical and subtropical zones of the world, less common in temperate zone, particularly more common in Asia; 18 genera (one endemic) and 199 species (102 endemic) in China.
The family* is very natural and is distinguished from others by having grayish white unicellular acicular hairs and pubescence throughout the plant. However, there are many different viewpoints about generic circumscription in the family. Ching recognized 18 genera (including Hypodematium) in his 1963 treatment (Acta Phytotax. Sin. 8: 289-335); soon afterward, in 1978 (Ching, Acta Phytotax. Sin. 16(3): 12-13), the number of recognized genera in China grew to 20 (Hypodematium was removed and placed in its own family). In 1971, Holttum subdivided this family in the Paleotropics into 23 genera (Blumea 19(1): 17-52). In 1977, Pichi Sermolli, mainly following Holttum, circumscribed other genera for a total of 32 genera (Webbia 3(2): 213-512). In 1990, A. R. Smith divided the family into five genera (in Kramer & Green, Fam. Gen. Vasc. Pl. 1: 263-272), i.e., Thelypteris (including five subgenera), Phegopteris, Pseudophegopteris, Macrothelypteris, and Cyclosorus (including 20 subgenera). Of the many systems, those of Holttum and Pichi Sermolli divide the family most finely, with the greatest number of genera. Holttum (loc. cit.) segregated the following genera from Cyclosorus s.l.: Amphineuron, Christella, Pneumatopteris, and Sphaerostephanos. Recognition of these genera was based on several characters, including whether the proximal pinnae were shortened or not, and whether the sporangia and sporangial stalks bore hairs or glandular hairs. Holttum (loc. cit.) also segregated several genera (e.g., Parathelypteris and Coryphopteris) from the classical