Kelp
Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera.
Laminariaceae
Laminariaceae is a family of brown algal seaweeds, many genera of which are popularly called "kelp." The table indicates the genera within this family. The family includes the largest known seaweeds: "Nereocystis" and "Macrocystis".