About Cystopteris fragilis (L.) Bernh.
Cystopteris fragilis (L.) Bernh. has a short, black rootstock. Its leaves reach 5 to 25 cm in length, and grow from fleshy petioles that have few or no long hairs. The petioles are approximately half the length of the leaf blade. Each leaf is split into many pairs of leaflets, and every leaflet is further subdivided into lobed segments. The leaflets are narrowly triangular and end in a sharp point. The underside of the leaf holds many rounded sori that contain the sporangia. Young Cystopteris fragilis is reported to have a scent of bitter almond, caused by hydrogen cyanide present in its spores.
This species is native to regions including Finland. It grows in locations suited to its brittle structure, most commonly in shady, slightly moist areas, such as cracks and ledges on vertical rock faces, blockfields, and sometimes on flat cliff surfaces. It avoids the most acidic and barren cliffs, and particularly favors slightly lime-rich soil.
