A foliose red algae with a tough flat frond usually between 20 and 50 cm in length, but sometimes up to 1m. The algae grows directly from a small discoid holdfast gradually widening and subdividing. The stipe is inconspicuous, rarely to 5 mm long. Older parts may have small 'leaflets' along the margin especially where damaged. Dark red, with purple tints under water.Sometimes the blade divisions are wedge-shaped and finely dissected above or the blade has numerous linear divisions throughout. This phenomenon seems to occur under fairly sheltered, silty conditions. Such plants are difficult to identify without examining the anatomical structure and the cortical cells in surface view, and have been confused with Callophyllis cristata (L. ex Turn.) Kütz. and Gracilaria foliifera (Forsk.) Børk (Irvine, 1983). Palmaria palmata has a multiaxial, pseudoparenchymatous construction and, in section, can be seen to consist of a large-celled medulla bounded on each side by a small-celled cortex.