Description: Thallus to 1m. reaching 5 m.long, linear, leatherly, compressed without a midrib and irregularly dichotomously branched. Large air bladders, 2.5 to 5 cms long and ovoid in shape, at intervals along the main axis.

Habitat: Common, often dominant, except on exposed shores. Epilithic in the mid-littoral.

Distribution: Common all around the British Isles. Europe: Portugal, Atlantic coasts of Spain and France, Baltic Sea, Norway, Sweden, Faroes, Spitzbergen, Iceland. Greenland. Atlantic coasy of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island, New Jersey and Delaware.

Similar Species: Fucus vesiculosus has air bladders in pairs one on either side of a mid-rib.

Key Identification Features:

• Probably the best known alga. The large single air bladders make the species unmistakable.

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

iNaturalist: Ascophyllum nodosum at iNaturalist World Species Observations database.

WoRMS: Ascophyllum nodosum at World Register of Marine Species.