Patterns of environmental conditions prevailing in coastal desert fog zones provide habitats extremely favorable for lichen growth. Phylogenetically related groups of lichens occur in geographically isolated desert fog zones, but endemism at both the species and genus levels is relatively high. The ecological importance of lichens in these regions is related to morphological and physiological adaptations to water uptake in both a liquid and vapor form. Much of this moisture is unavailable to vascular plants, allowing a large biomass of lichens to occur in areas with little or no vascular plant cover. The relative importance of fruticose lichens in such habitats, in comparison to crustose and foliose forms, is determined largely by the physical form of atmospheric moisture.