A genus of large brown seaweeds in which the thallus may reach lengths of 50 m or more. The upper portions of the plant float on the sea surface, buoyed up by air bladders. Macrocystis can grow in much deeper waters than most other seaweeds, e.g. to depths of 30 m or more in clear seas. It occurs in Antarctic regions, on the Pacific coast of N. America, and off the shores of S. Africa. In the USA, Macrocystis is harvested as a valuable source of algin.
Subjects: Plant Sciences and Forestry.