Syn. Cystoseira discors (Linnaeus) C.Agardh 1828
Recognisable by spiny, prominent axis and branches, that can be both cylindrical and leaflike. Mostly a caespitose species, it can grow up to 80 cm tall but is usually smaller. Fertile in spring.
Intertidal, shallow subtidal. Prefers sheltered locations (tide pools. bays, occasionally lagoons).
Widespread, but localised. Often grows with C. compressa and C. humilis. Mostly retreats into shallow areas, where it is safe from urchin grazing.
- C. foeniculacea f. foeniculacea – Spiny axes, with both flattened and cylindrical branches.
- C. foeniculacea f. latiramossa – Spiny, but with completely flattened primary and secondary branches. Much more delicately built. Very rare.