Adiantum tenerum, common name brittle maidenhair fern, is a species of maidenhair fern belonging to the family Pteridaceae.
This fern species is native to Florida (United States), Mexico, Puerto Rico, Cuba, Jamaica, Bahamas, Costa Rica, Nicaragua, Colombia, Brazil, and Venezuela.
It is restricted to moist, shaded, limestone ledges and grottoes.
Adiantum tenerum grows in a creeping position. Leaves are light green, pinnate, fan-shaped, glabrous, arching or pendent, about as long as broad.