Bladderwrack

Fucus vesiculosus

Dried seaweed was the first source of iodine and alkalies needed to manufacture soap and glass, both of which were synthesized from the compounds sodium and potassium.

Bladderwrack is so-named because the plant contains tiny sacs that resemble bladders. As with other species of brown algae, the cell walls of the plant contain a high degree of alginic acid. Also known as algin, this polysaccharide bonds to water molecules to form a gelatinous material that is used in the food, cosmetic and textile industries.

Historically used in the British Isles as an alternative for manure and artificial fertilizer for broccoli and potato crops, dried bladderwrack was sprinkled on the ground or burnt and the ash used in the same way.