Rockweed is a brown algae found on rocky shores. The most common types of rockweed are within the genus Ascophyllum spp. and Fucus spp. (the latter is shown to the left). They grow slowly and can live from 3 to 15 years before breakage. Rockweeds have fronds that bear air bladders. These 'airbags' help the algae to stand up straight under water. Rockweed lacks true roots, stems, and leaves, and because they lack a vascular system, absorb dissolved nutrients directly through the blades. Rockweed attaches to rocks with a disc-like “holdfast”, and regenerate fronds from remaining holdfasts after a natural disturbance that removes upright fronds.
