Description: Thallus erect, axes polysiphonous to 20 cms long, terete. Densley branched with 11 - 21 pericentral cells. Corticate on major axes or near holdfast. Cystocarps ovoid to urceolate.

Habitat: Common. Epilithic, shells and artifical materials from the mid littoral to 20 m in the sublittoral..

Distribution: Widely distributed around the British Isles from the Shetlands to the Channel Islands. Europe: Portugal, Spain, France, Baltic Sea, Netherlands, Norway, Swedfen, Faroes and Iceland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island, New Jersey, Delaware, Maryland and Virginia. Further afield: Arctic Sea including Baffin Bay, Canary Islands, Alaska, Mauritius and Australia.

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

iNaturalist: Polysiphonia fucoides at iNaturalist World Species Observations database.

WoRMS: Polysiphonia fucoides at World Register of Marine Species. Accepted name: Vertebrata fucoides (Hudson) Kuntze, 1891. AphiaID: 637672.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Rhodomelaceae; Polysiphonieae; Polysiphonia