Cartilaginous, dark purplish-red, red, yellowish or greenish fronds to 150 mm high, gametophyte plants are often iridescent under water when in good condition. Stipe compressed, narrow, expanding gradually to a flat, repeatedly dichotomously branched frond, in tufts from a discoid holdfast. Axils rounded, apices blunt or subacute, frond thicker in centre than margins. Very variable in breadth of segments. Very variable in branching, colour and thickness.