Frond ca.10cm long. Recorded from all coasts of the British Isles. However, records from the east coasts are sparse, presumably due to the lack of suitable substrata. It may occasionally be epiphytic on Laminaria hyperborea stipes. A conspicuous crimson seaweed up to 300mm in length.
Blades are oval or lanceolate, leaf like and reminiscent of beech leaves.
The membranous lamina has a wavy margin and is supported by a conspicous midrib with opposite pairs of lateral veins. The leaves may be pointed in young specimens. In winter the membranous lamina is lost so that only the midrib remains. Cystocarp are globular, with a membranous border, and form in fairly close formation on a short stalks on female plants. New fronds may grow before all cystocarp disappear.