Ascophyllum

Ascophyllum nodosum is a large, common cold water seaweed or brown alga (Phaeophyceae) in the family Fucaceae, being the only species in the genus Ascophyllum. It is a seaweed that only grows in the northern Atlantic Ocean, also known in localities as feamainn bhuí, rockweed, Norwegian kelp, knotted kelp, knotted wrack or egg wrack. It is common on the north-western coast of Europe (from Svalbard to Portugal) including east Greenland and the north-eastern coast of North America, its range further south of these latitudes being limited by warmer ocean waters. A. nodosum has long tough and leathery fronds, irregularly dichotomously branched fronds with large, egg-shaped air bladders set in series at regular intervals along the fronds and not stalked. The fronds can reach 2 m in length and are attached by a holdfast to rocks and boulders. The fronds are olive-green, olive-brown in color and somewhat compressed, but without a midrib. Its life history is of one diploid plant and gametes. Each individual plant is either male or female. The gametes are produced in the spring in conceptacles embedded in yellowish receptacles on short branches.