Fucus is a genus of brown algae found in the intertidal zones of rocky seashores almost throughout the world.

The base of the thallus is stipe-like due to abrasion of the tissue lateral to the midrib and it is attached to the rock by a holdfast.

[2] These algae have a relatively simple life cycle and produce only one type of thallus which grows to a maximum size of 2 m.[citation needed] Fertile cavities, the conceptacles, containing the reproductive cells are immersed in the receptacles near the ends of the branches.

After meiosis, oogonia and antheridia, the female and male reproductive organs, produce egg cells and sperm respectively that are released into the sea where fertilisation takes place.

This contrasts with the life cycle of the flowering plant,[3][4] where the egg cells and sperm are produced by a haploid multicellular generation, albeit very strongly reduced, and the egg cells are fertilised within the ovules of the parent plant and then released as seeds.

They are dominant on the shores of the British Isles,[5] the northeastern coast of North America[6] and California.

Other brown algae can be found at the low-littoral such as Himanthalia, Laminaria saxatilis and Alaria esculenta.

[7] When washed up on beaches, kelp flies such as Coelopa pilipes feed and breed on Fucus algae.

[9] In 2005, it was announced that bacteria grown on Fucus have the ability to attack and kill the MRSA superbacterium.

[5] F. distichus is up to 10 cm long with a short stout cylindrical stipe, branching dichotomous, flat and with a mid-rib.