information:extraction
Description

The thallus (or body) consists of flat or leaf-like structures known as blades that originate from elongated stem-like structures, the stipes. A root-like structure, the holdfast, anchors the kelp to the substrate of the ocean. Gas-filled bladders (pneumatocysts) form at the base of blades of American species, such as Nereocystis lueteana, (Mert. & Post & Rupr.) to hold the kelp blades close to the surface.