Description: Thallus in dense tufts, axes polysiphonous to 25 cms or more long, much branched with 4 pericentral cells, ecorticate. Cystocarps urceolate.

Habitat: Abundant. Epilithic, epiphytic and epizoic in rock pools at low littoral to 20 m in the sublittoral.

Distribution: Generally distributed around the British Isles from the Shetlands to the Channel Islands. Europe: the Mediterranean, Spain, France, Netherlands, Baltic, Norway, the Faroes and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and New Jersey. Further afield: Arctic Sea including the Baffin Sea, the Canary Islands and Argentina.

Key Identification Features:

• 4 pericentrals, Cystocarps urceolate.

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

iNaturalist: Polysiphonia stricta at iNaturalist World Species Observations database.

WoRMS: Polysiphonia stricta at World Register of Marine Species.