It has a short, black rootstock. The leaves are up to 5-25 cm and are borne on fleshy
petioles with few or no long hairs. The petioles are about half the length of the leaf blade. Each leaf is divided into many pairs of leaflets, each of which is subdivided into lobed segments. The leaflets are narrowly triangular and
apiculate. The underside of the leaf has many rounded
sori containing the
sporangia. A young
Cystopteris fragilis is said to have the scent of
bitter almond, which is caused by spores that contain
hydrogen cyanide. == Habitat ==