Oriented arrays of epicuticular wax plates inEucalyptus species

Summary

Patterns of arrangement of epicuticular wax platelets are shown in a number of species ofEucalytpus. In some, wax platelets are oriented across the long axes of epidermal cells overlying veins and, in some species, over cells of adjacent stomatal complexes. Among other patterns, radial arrangements around stomata, arrangements in lines at right angles to underlying cell walls and concentric arrays are described. The possibility of the involvement of ectodesmata (ectocythodes) in the location of wax platelets is raised. The pattern of orientation of the platelets is ascribed to a “prepattern”, as yet unobserved, of anisotropic domains in the outer cuticle. It is suggested that this prepattern may consist of regions of molecular anisotropy possibly produced in response to stretching of the cuticle during expansion growth. Wax platelet patterns appear to be restricted to certain taxonomic entities; thus, genetical determinants are also involved in their formation.