Photosynthetic costs of foliar variegation in Begonia

Foliar variegation is often assumed to be due to lack of chlorophyll or the presence of special pigments in sections of a leaf, but it can also result from leaf structural variation. Sheue et al. show that naturally occurring foliar variegation in six species and one cultivar of Begonia is due to air spaces above the chlorenchyma, situated either below the adaxial epidermis or below the adaxial water-storage tissue. Photosynthetic functioning is retained in the light areas of the leaves, and these areas do not include primary veins, potentially limiting the costs of variegation.