Occurrence of Unusually Large Plants of Grateloupia in the Vicinity of Portsmouth

Abstract

WE would like to draw attention to a spectacular seaweed which, although locally common in the Portsmouth area, has so far been unrecognized, at least in this form, in the British flora. The plant in question grows attached to stones in sheltered situations exposed at the lowest tides and in the sublittoral area. It is a deep brownish red in colour and luxuriant specimens attain a length of up to 60 cm, making it one of the largest of the red algae in Britain. The erect fronds arise from a small discoid base and are usually alternately branched, flattened, spirally twisted and attenuate at base and apex. The fronds gradually develop spine-like protuberances from margins which grow into fringes of curved, pointed ramuli about 4 cm long; similar ramuli often grow out from the surface of the lamina producing a plant of very distinctive appearance (Fig. 1). In some cases the ramuli themselves become flattened and produce further proliferations.