Thallus bushy, yellow to dark brown, 150-500 mm long; tough, cylindrical, repeatedly irregularly branched to the third or fourth order. With characteristic round-elliptical air bladders about the size of a small pea, generally formed singly but sometimes in series, in the centre of branches. Base dark brown to black and persisting for many years to produce new second-order branches each year.
Habitat:
Lower intertidal in large sandy pools, mostly in persistent stands.
Distribution:
S England, W Ireland north to W Scotland.
Key characteristics:
Intercalary air bladders.
