AbstractChlorophyll concentrations and a/b ratios of 31 moss species in 16 families collected from various habitats in Kansas were lower than those of most higher vascular plants. Most of the mosses examined had higher chlorophyll concentrations and lower chlorophyll a/b ratios when collected from habitats with low solar irradiance, relative to mosses collected from habitats characterized by high irradiance. This was true for mosses collected from under a forest canopy compared with those collected from exposed sandstone outcrops, and for the same populations of mosses collected before and after forest canopy closure. Such changes in the characteristics of the light-harvesting pigment system appear to represent adaptations enhancing the efficiency of light capture.