the uneven coloring of leaves, forming a unique design. Variegation may depend on such anatomic features as the formation of pneumatic cavities under the epidermis (imparting to the leaf a silvery coloring), the uneven distribution of hairs, and the absence of stomata (giving the leaf a mat appearance). Variegation also results from the formation in some cells of such pigments as anthocyanins, which impart a red coloring, and phytomelanins, which impart a black coloring. The loss of coloring substances in chlorophyll grains causes the appearance of light green, yellow, or white areas on the leaf. Variegation may be characteristic of a plant species or variety. The design, in the form of irregular spots or a ring, may be concentrated along the veins or margin of the leaf or may be distributed over the entire leaf.
If the variegation is the result of somatic mutation, the variegated plants are chimeras, whose different tissues have diverse genetic constitutions. For example, in variegated pelargonium, the white areas give rise to white offspring, and the green areas to green offspring. Variegated plants are widely used as ornamentals and in genetic research. They are useful in studying morphogenesis, especially if the variegation is based on a change in the coloring of chlorophyll grains, which often depends on the interaction of genes of the nucleus with genes of the chlorophyll grains.
V. L. RYZHKOV