Wireweed    Sargassum muticum



The common name of many animals and plants can vary between different regions, different people or even between different experts.  For example this brown seaweed is called Wireweed in one seaweed identification book, Japanese Weed in another and Sargassum in a third.  This is why it is always good to know the scientific name because it will not change based on where you are or who you talk to.  


Many of you may have already heard of the scientific name before because another related species occurs in the middle of the Atlantic Ocean in what is called the Sargasso Sea. The name was given by Christopher Columbus's crew apparently based on the presence of vast amounts of floating seaweed.  By the way the Sargasso Sea is not a sea but an area where large scale Atlantic currents bring in drifting material and keep it there forming a unique ecosystem.


This species today can be found both in Japan and from Alaska to Southern California.  However it was introduced to the Pacific Northwest in the 1920's when the first oysters were imported from Japan to expand the local oyster culture program.  It occurs in the lower intertidal and upper subtidal zones including tidepools.  While normally occurring in sheltered waters it can also be found in wave impacted areas within Puget Sound.


Sargassum is characterized by long thin stems with multiple side branches supported by small, round bladders or floats.  Like other introduced species it can often out compete local species and form an extensive floating canopy.