Pylaiella littoralis (Linnaeus) Kjellman
Description: Thallus filamentous, up to 200 (-500) mm long. Erect vegetative system of branched uniseriate filaments; branching irregularly opposite. Occasional longitudinal cell divisions. Basal system of free filaments and rhizoids. Many discoid chloroplasts per cell. Unilocular sporangia intercalary, sometimes terminal; plurilocular sporangia also intercalary, sometime terminal.
Habitat: Intertidal to shallow subtidal; epilithic or epiphytic, particularly on fucoids (particularly Ascophyllum nodosum). Occurs in marine and estuarine conditions.
Key characteristics: Rope-like appearance; tolerance of emersion.