A revised classification of leaf variegation types

Variegated leaf plants are a group of plants with stable patterns of differently colored leaf areas. The variously colored patches on the surface of the leaves have important biological functions in plant reproduction and adaptation to the environment. Apart from that, these plants have attracted interest as valuable ornamental plants. In this study, 1710 species with variegated leaves belonging to 78 families were investigated based on field-collected samples and previous literature, including transverse sections of 117 species. The macroscopic patterns of variegated leaves are highly diverse and can be distinguished as fishbone-shaped, blotched, V-shaped, spotted, striped, reticulate, and pinnate, with varying levels of diversity across different families and genera. We classified variegated leaves into five types according to the location, shape, color, and cross-sectional structure of the differently colored leaf areas. These are: I, chlorophyll type; II, air space type; III, epidermis type; IV, pigment type; and V, appendages type. Type II is the most common type, which is found in approximately 56% of all variegated leaf species, whereas type V is newly defined to accommodate the variegated leaves with colored, unequally distributed, multicellular outgrowths on the epidermis. Relationships between the diverse macroscopic patterns and the five structural types are discussed.