a family of brown algae of the order Fu-cales. The bushy thallus is about 1–2 m long; sometimes it reaches a length of 10 m. The base and trunk are often perennial. The branches are annual and grow out of the axils of leaflike blades. Each oogonium has one egg cell, which after emergence to the outside remains attached to the maternal plant by a mucous stalk until fertilization and development of a multicellular growth.
The six genera embrace more than 150 species, most of which belong to the genus Sargassum. The algae grow near shore on the bottom of warm seas. Large floating masses of Sargassa-ceae, which have become detached from the substrate and have reproduced vegetatively, are present in the Sargasso Sea—a region in the western part of the Atlantic Ocean. Seven species of the genus Sargassum are found in the USSR, in the Sea of Japan, off southern Sakhalin, and off the southern Kuril Islands. One species of the genus Coccophorus is found in the southern part of Primor’e Krai.
Sargassaceae are used to obtain alginates; in Southeast Asia some species are used as food.