Greek mikros, small, + lepis, scale, alluding to the small, cuplike indusia of this genus.

Plants medium-sized to large, terrestrial. Rhizomes long-creeping, hairy. Fronds close or remote, more or less hairy. Stipes grooved. Blades 2- to 3-pinnate to 3-pinnate-pinnatisect; rachises adaxially grooved, grooves continuous with those of pinna costae. Veins free, ending in hydathodes short of margins. Sori terminal on veins, marginal or submarginal. Indusia pouch- or pocket-shaped, attached at bases or at bases and sides, opening outward, often hairy.

A mostly Asian-Pacific genus of about fifty species ranging from Japan to New Zealand and Madagascar, Africa, and the American Tropics (where it probably is not native). Represented in Hawai 'i by two indigenous species and a hybrid between them.

There are unresolved problems in this genus in Hawai 'i, and further study may lead to the recognition of more species.