Description: Thallus growing from a minute holdfast to produce a simple monostromatic blade up to 13 cms long and 10 cms wide.

Habitat: Common throughout the littoral but mainly in the upper littoral. Epilithic on rock, wood or concrete. Epiphytic on limpets or mussels and epiphytic on other algae.

Distribution: Widespread throughout the British Isles. Europe: Mediterranean, Portugal, Spain, France, Netherlands, Helgoland, the Baltic, Norway, Sweden, the Faroes and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island and Virginia. Further afield: the Canary Islands.

Similar Species: Other species of Purpurea.

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

iNaturalist: Porphyra umbilicalis at iNaturalist World Species Observations database.

WoRMS: Porphyra umbilicalis at World Register of Marine Species.