Greek kyklos, circle, + soros, heap (a term used in botany for sorus), a reference to the round sori of this, and many other genera, in the family Thelypteridaceae.

Growth habit and general features like those of Thelypteridaceae. Blades 1-pinnate-pinnatifid; rachises and costae bearing many short, white, sharp-tipped hairs. Pinnae lower surfaces bearing variable, capitate hairs and red, sessile"glands, lower surfaces of costae with scattered, thin, flat, triangular scales, bases of sinuses with cartilaginous membranes. Lowermost veins of adjacent pinna lobes joining to form excurrent vein to base of sinuses, next distal vein pair very oblique and extending to sides of sinus membranes.

A pantropical genus. Holttum (1977) provided the only modern review of the Pacific and Australasian Thelypteridaceae (including all the Hawaiian taxa then known), which is followed here and includes only one species (Cyclosorus interruptus) in this genus.

Represented in Hawai 'i by a single indigenous species.