Perennial. Rhizome creeping or erect, covered with scales, bristles or woolly hairs. Fronds tufted or separated, usually small. Stipe stiff, polished dark red-brown or black, scaly at base, sometimes hairy above. Lamina 1–4-pinnate, thin, glabrous or very sparsely hairy (in Australian species); pinnae more or less fan-shaped, often asymmetric at base, membranous or coriaceaous; veins radiating outwards, repeatedly forked, free, without main vein. Sori oblong or reniform, marginal, covered by strongly recurved marginal lobes.
About 220 species world-wide; 9 in Australia, 5 in Victoria.
Among the most easily recognised leptosporangiate fern genera. All species share a unique character: sporangia borne on the reflexed leaf margin or "false indusium" (pseudoindusium) (Huiet et al 2018).
Huiet, L.; Li, F-W.; Kao, T-T.; Prado, J.; Smith, A.R.; Schuettpelz, E. & Pryer, K.M. (2018). A worldwide phylogeny of Adiantum (Pteridaceae) reveals remarkable convergent evolution in leaf blade architecture, Taxon 67(3): 488-502.