Botryocladia wrightii (Harvey) W.E.Schmidt, D.L.Ballantine & Fredericq

Fucus vesiculosus

Also known as Chrysymenia wrightii (Harvey) Yamada

Common names: Wright's Golden Membrane Weed or 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.
Habitat: 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, SW England in September 2013 by Francis Bunker. W Ireland in 2019 (Cilian Roden). On marinas, rocks in the lower intertidal and in pools; subtidal to 14 m (NW Spain). Currently restricted to W Ireland. 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.

Identification guide for selected marine non-native species (National Museum Wales). (Download free PDF, about 3.5 Mb).

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.