Dictyota dichotoma (Hudson) J.V. Lamouroux
Description: Thallus flat and leaf-like, to 300 mm long (usually 100-150 mm) and 5-30 mm broad; fronds thin and translucent, olive to golden-brown, occasionally with a bluish iridescent, and ± regularly dichotomously forked, but lacking a midrib, and the reproductive structures are scattered over the fronds. Very variable, with narrow spirally twisted plants being found in mid-tidal pools, broader less twisted and more regularly branched plants being found in lower tidal pools (above), and broader very regularly branched, less twisted plants in the subtidal (below). Often growing epiphytically. It is likely that more than one species is represented in Britain and Ireland.
Habitat: pools from mid-tide and below (see below).
Distribution: Widely distributed and common.
Key characteristics: Absence of midrib, ± regular branching, reproductive structures scattered.