Description: Erect densely and irregularly branched in tufts of uniseriate filaments to 20 cms long, ecorticate. Plurilocular sporangia relatively short without a terminal hair.

Habitat: Common. Epiphytic or epilithic, low littoral to about 10 m sublittoral.

Distribution: Widespread in temperate waters. The British Isles. Europe: Mediterranean, Portugal, Spain, France, Netherlands, Germany, Baltic Sea, Norway and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island, New Jersey and Delaware. Further afield: the Canary Island, Souh Africa and Chile.

Similar Species: Many finely branched brown algae are similar. Microscopic examination is required for determination.

Key Identification Features:

• Ribbon shaped plastids and plurilocular sporangia without a terminal hair.

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

iNaturalist: Ectocarpus fasciculatus at iNaturalist World Species Observations database.

WoRMS: Ectocarpus fasciculatus at World Register of Marine Species. Accepted name: Ectocarpus flagelliformis Kützing, 1843. AphiaID: 145405.

Classification: Biota; Chromista; Harosa; Heterokonta; Ochrophyta; Phaeophyceae; Fucophycidae; Ectocarpales; Ectocarpaceae; Ectocarpus