Either any seaweed of the genus Laminaria or, more specifically, L. hyperborea. This is a large seaweed, with fronds that can measure up to 3.5 m long. The stipe is stiff, tapers towards the top, and has a rough-textured surface which provides a suitable substrate for many epiphytic seaweeds. The blade is divided into a number of strap-like ribbons and is oar-shaped in outline. The holdfast consists of numerous thick, root-like branches. It is found just below low-water mark, attached to rocks.
Subjects: Plant Sciences and Forestry.