Ceramium nodulosum is a small red marine alga. There is confusion surrounding this name.
Ceramium nodulosum is a small filamentous branching alga growing to a height of 30 cm in tufts of erect branches usually fully corticate. The apices of main axes are straight or slightly curled inward at the tips. It attached by a rhizoids with many erect branches. The axes and branches are usually fully corticate and, unlike some other species, it is without spines.
Gametophytes are dioecious. Cystocarpes and tetrasporasngia are formed on the branches.
Generally found around Great Britain and Ireland.
There is some confusion with this name. As described above the species is Ceramium nodulosum (Lightfoot) Ducluzeae. The species Ceramium virgatum Roth is noted as a possible synonym elsewhere.