Macrocystis
genus of Phaeophyceae
Macrocystis is a monospecific genus of kelp (large brown algae) with all species now synonymous with Macrocystis pyrifera. It is commonly known as giant kelp or bladder kelp. This genus contains the largest of all the Phaeophyceae or brown algae. Macrocystis has pneumatocysts (air bladders) at the base of its blades. Sporophytes, the macroscopic forms, are perennial and the individual may live for up to three years; stipes/fronds within a whole individual undergo senescence, where each frond may persist for approximately 100 days. The genus is found widely in subtropical, temperate, and sub-Antarctic oceans of the Southern Hemisphere and in the northeast Pacific. Macrocystis is often a major component of temperate kelp forests.
Despite its appearance, it is not a plant, but a stramenopile. Giant kelp is common along the coast of the northeastern Pacific Ocean, from Baja California north to southeast Alaska, and is also found in the southern oceans near South America, South Africa, Australia, and New Zealand. Individual algae may grow to more than 45 metres (150 feet) long at a rate of as much as 60 cm (2 ft) per day.
“Macrocystis” enters the record as genus of Phaeophyceae. Crown Archives preserves that source wording while asking what Macrocystis, genus and Phaeophyceae can confirm, complicate or overturn.
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“Macrocystis” is worth following because a concise public description often conceals a longer documentary argument. Here, Macrocystis, genus and Phaeophyceae provides the most credible route into that argument.
The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Sep 17, 2026. The linked authority identifier is Q2304985. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Macrocystis” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.