Description: Thalli erect to 2 m long and 3 mm, or more, wide. Flattened and with opposite distichous branches which branch in a similar manner, all flattened, tapering at both base and apex. A faint midrib is discernable in the main axis and branches, the ultimate branches are spine-like and in summer may show a short tuft of uniseriate filaments at the tip.

Habitat: Mainly sublittoral to 12 m. More common on the south-western shores.

Distribution: Recorded from most shores of the British Isles except the east which is generally poor for many algae. Europe: Meriterranean, Portugal, Atlantic coasts of Spain and France, Belgium, Norway, Faroes, Jan Mayen and Bjornoya and Iceland. Atlantic coast of North America: Canada. Further afield: Morocco, Pacific coast of America from Alaska to Chile, Indo-Pacific, Japan, Australia, Tasmania, New Zealand and Antarctica.

Key Identification Features:

• Quite distinctive, large, flattened with opposite branching.

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

iNaturalist: Desmarestia ligulata at iNaturalist World Species Observations database.

WoRMS: Desmarestia ligulata at World Register of Marine Species. Accepted name: Desmarestia ligulata (Stackhouse) J.V.Lamouroux, 1813. AphiaID: 145309.

Classification: Biota; Chromista; Harosa; Heterokonta; Ochrophyta; Phaeophyceae; Fucophycidae; Desmarestiales; Desmarestiaceae; Desmarestia