Knotted Wrack

Knotted or egg wrack (Ascophyllum nodosum) on the beach at Lundin Links. This is said to be a widespread seaweed but I hadn't spotted it before. The egg-shaped air bladders were about the size of small grapes.

Growing on the egg wrack was the fluffy dark red seaweed, egg wrack wool (Polysiphonia lanosa). It was said to be an obligatory epiphyte - a plant that benefits from growing on another plant for physical support. It makes use of the hosts buoyancy at high tide lifting it closer to the sunlight.

However, the nature of Polysiphponia's relationship with Ascophyllum is still subject to debate. Recent researchers have suggested that Polysiphonia is parasitic as it gains sugars from its host via hyphae sunk into egg wracks tissue. Others suggest Polysiphonia would not still have red photosynthetic pigment if it was a true parasite and hence suggest the relationship is epiphytic.