Description: Thallus large to 3 m long with midrib 3 cms wide along full length of frond. Blade mambraneous and pinnatifid. Pinnae to 80 cms long. Attached by strong rhizoids

Habitat: Abundant in the sublittoral mainly in estuaries. Capable of tolerating low salinity.

Distribution: British Isles: only reported from the south coast of England around the Isle of Wight, Devon and Channel Islands. Europe: Mediterranean, N.France. Further afield: Australia, New Zealand, Tasmania, Argentina, California, Japan, Korea and China.

Similar Species: Alaria esculenta is not so broad but does have a midrib. Without a pinnatifid blade.

Key Identification Features:

• Large membraneous with a pinnatifid blade.

Distribution Map from NBN: Undaria pinnatifida at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Undaria pinnatifida at iNaturalist World Species Observations database.

WoRMS: Undaria pinnatifida at World Register of Marine Species. Accepted name: Undaria pinnatifida (Harvey) Suringar, 1873. AphiaID: 145721.

Classification: Biota; Chromista; Harosa; Heterokonta; Ochrophyta; Phaeophyceae; Fucophycidae; Laminariales; Alariaceae; Undaria