Rhizome wiry, thread-like, widely creeping and branching freely. Delicate fern, stipe glabrous; lamina often irregular, 2- or 3-pinnatifid, glabrous; blade tissue is only one cell thick; pinnae lobe margins entire. Sori are at the apex of the lobes, 1 or 2 per pinna, sporangia covered by indusium flaps; spores green.

Variable fern changing form and size according to amount of humidity and protection. When not growing under very wet conditions, it may dry out during the summer months but recovers fast after the first winter rains.

Greek: hymen = membrane, a skin; phyllon = a leaf; referring to the membranous or delicately transparent filmy fronds.

Latin: capense = Cape of Good Hope, where the fern was first collected and described in 1818.