Kelp
Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera.
Kelp
Through the 19th century, the word "kelp" was closely associated with seaweeds that could be burned to obtain soda ash (primarily sodium carbonate). The seaweeds used included species from both the orders Laminariales and Fucales. The word "kelp" was also used directly to refer to these processed ashes.