Cnemidaria is a genus of small tree ferns in the family Cyatheaceae. They are subaborescent or marginally aborescent, growing as tall as 3.5 m with a trunk (basically a single large stem) diameter of 7 cm.
The fronds of the Cnemidaria are typically 1-3.5 m long and pinnate. The rachis is generally smooth, but in some species it is slightly spiny. Presence or absence of spines has been used as a diagnostic factor to distinguish between species. Young fronds are frequently covered with scales or spines. They uncurl by circinate vernation. The sori are circular and present on the underside of the pinnules away from the margins (edges). Chromosome number is n=69.
The species of Cnemidaria are distributed in the New World tropics, from Puerto Rico and the Caribbean to Central America and south to the northern Andes and parts of southeastern Brazil. They prefer wet mountain areas and cloud forests in deep shade and in forest margins, clearings and disturbed sites. They are aggressive colonizers, and are quite fire resistant.