Cystopteris fragilis is a species of fern known by the common names brittle bladder-fern and common fragile fern. It can be found worldwide, in shady, moist areas. The leaves are up to 30 or 40 centimeters long and are borne on fleshy petioles.
Fragile Fern is found in the cracks and crevices of cliffs, rock outcrops, rocky slopes, banks and ravines, usually in shade. It is a rather variable species, but if you see a fern clump growing on rock (or thin soil over rock) with fronds (including the stem) not more than 14 inches long, lacks any hairs, scales or glands on the pinnae or upper stem, the lowest pinnae pair is at least slightly smaller than the second lowest, and sori are on most fronds in a row about midway between the pinnule midvein and edge (without indusia when mature), chances are it is Cystopteris fragilis. It is harvested from the wild for local use as a food, medicine and source of materials.