Description from Flora of China
Plants small, usually on rocks. Rhizomes short, erect or ascending with dictyostele, or occasionally long creeping with siphonostele; scales colorless or brownish, thin. Fronds strongly dimorphic, clustered or rarely scattered, sterile fronds shorter than fertile ones; stipe dark brown proximally, light brown to straw-colored distally, grooved adaxially, scaly. Sterile fronds: lamina broadly ovate or oblong, 2-4-pinnate, membranous to leathery, glabrous. Fertile fronds: lamina 2- or 3-pinnate. Ultimate segments of sterile lamina ovate, spatulate, elliptic, or fan-shaped; fertile segments linear or elongate oblong. Veins free, pinnately branched, simple or forked distally; hydathodes often sunken below surface on dried specimens. False indusia broad, clearly marginal, continuous, making a single fertile segment podlike. Sori borne at vein tips, orbicular or elliptic, confluent when mature. Spores yellow, tetrahedral, trilete, verrucose. x = 30.
Plants of Cryptogramma resemble those of Onychium but are smaller, strongly dimorphic, and have fertile fronds markedly taller than sterile fronds. There is not a commisural vein connecting veinlet tips, so the sori are borne at veinlet tips and become confluent only when mature.
About ten species: temperate and subtropical alpine regions, Asia, Europe, North and South America; three species in China.
(Authors: Zhang Gangmin (张钢民); Edward R. Alverson, Jordan S. Metzgar)