Harvesting of fog water by epiphytes is biomechanically analogous to filter-feeding by aquatic invertebrates. Increased branchiness, as measured by fractal dimensionality, should reflect greater fog-harvesting ability. We documented changes in epiphytic macrolichens across an altitudinal gradient in fog availability in a coastal shrubland in northern Chile. Fruticose and foliose genera appear to become more abundant with increased fog availability. Fractal dimension of fruticose and foliose lichens increased significantly with inferred fog availability. The adaptive morphology of lichens is under-studied, and insights from theoretical morphology of other organisms yield fruitful hypotheses for further studies.