Abstract
In an intertidal population of Pterocladiella capillacea from southern Baja California, Mexico, fronds that lacked their main apex were bushier than intact fronds. A multivariate statistical analysis showed that the absence of the main apex was associated with higher frond biomass, a higher degree of branching, higher frond width, and longer main branches. The variation in frond form when the main apex is absent might be a response to the loss of apical dominance. The potential relevance of this morphological plasticity for the survival of thalli in the intertidal zone is discussed.