The erect frond of dulse grows attached by its discoid holdfast and a short inconspicuous stipe epiphytically on to the stipe of "Laminaria" or to rocks. The fronds are variable in shape and colour from deep rose to reddish purple and are rather leathery in texture. The flat foliose blade gradually expands and divides into broad segments ranging in size to long and in width which can bear flat, wedge-shaped proliferations from the edge. The blade consists of an outer cortex of small cells enclosing a medulla of larger cells up to 0.35 thick.