Sargassum that also can mean all seaweed species washed up on shore. "Sargassum" species are found throughout tropical areas of the world and are often the most obvious macrophyte in near-shore areas where "Sargassum" beds often occur near coral reefs. The plants grow subtidally and attach to coral, rocks, or shells in moderately exposed or sheltered rocky or pebble areas. These tropical populations often undergo seasonal cycles of growth and decay in concert with seasonal changes in sea temperature. In tropical "Sargassum" species that are often preferentially consumed by herbivorous fishes and echinoids, a relatively low level of phenolics and tannins
Plant cell quite elongated, and may divide transversely to give a septate appearance. The role of this cell type is to support the plant in axes still growing in length, and to confer flexibility and tensile strength on tissues. The primary wall lacks lignin that would make it tough and rigid, so this cell type provides what could be called plastic support – support that can hold a young stem or petiole into the air, but in cells that can be stretched as the cells around them elongate. Stretchable support (without elastic snap-back) is a good way to describe what collenchyma does.