Sargassum johnsonii leaves. Sargassum johnsonii Sargassum johnsonii Chapman, 1961, is a brown seaweed of the genus "Sargassum" that is endemic to the Three Kings Islands in New Zealand. It is sometimes called totara weed because of the resemblance to the foliage of the NZ native tree totara. Its scientific name derives from its discoverer, Magnus Earle Johnson, Three Kings Islands explorer and captain of the yacht "Rosemary", who landed botanists on the islands on several occasions. "Sargassum johnsonii" grows in rocky intertidal habitats, often extending to the subtidal zone up to a depth of 40 m. It is a foundation species, and
Sargassum to cover the entirety of the Sargasso Sea, making navigation impossible, it has since been found to occur only in drifts. "Sargassum" species ares also cultivated and cleaned for use as an herbal remedy. Many Chinese herbalists prescribe powdered "Sargassum"—either the species "S. pallidum", or more rarely, hijiki, "S. fusiforme"—in doses of 0.5 gram dissolved in warm water and drunk as a tea. It is called in traditional Chinese medicine, where it is used to resolve "heat phlegm". Species of this genus of algae may grow to a length of several metres. They are generally brown or dark green in