Chrysymenia wrightii (Harvey) Yamada

Fucus vesiculosus
Also known as Wright's Golden Membrane Weed.

Description: Soft, gelatinous, compressed, red to brown-red fronds, to 400 mm long, filled with a watery mucilage and with small gland cells borne on inflated basal cells. Main axis simple, not jointed, without nodal diaphragms, not constricted. Very variable in branching pattern, 2-4 times branched (alternate, opposite or irregular) with branches constricted at the base and tapering at the tips; fronds often with many small proliferations. Alien species originally described from Hokkaido, Japan. It was first found in the Étang de Thau in 1978, a "hotspot of introductions." Plants were found on marinas in Falmouth, Cornwall in September 2013 by Francis Bunker.
Habitat: On marinas, rocks in the lower intertidal and in pools; subtidal to 14 m (NW Spain). Currently restricted to SW Britain, NW Spain and Mediterranean France. In its native range it occurs from the Russian Far East and Japan, south to Korea and China.

Fucus vesiculosus
Similar species: Lomentaria clavellosa, which is more regularly branched and forms tetrasporangia in disctinct sori rather than scattered in the cortical layer.

Species list

Photographs © David Fenwick. Falmouth Dock, Cornwall.