Functional micromorphology of petals of Chaenomeles japonica exposed to humid and cold season

In this study, micro- and nano-traits of petal epidermises of flowers of Chaenomeles japonica extended under environmental conditions, during the humid and cold period of the year, are presented. The outer (abaxial) and the inner (adaxial) epidermises of petals of C. japonica consist of convex and papillae cells, respectively, that are covered by epicuticular wrinkled relief further ornamented by submicron motifs, forming interfaces between floral tissues and environment. Structural epidermal features of the petal relief at the nanoscale level reveal different functionality on the two sides of the corolla. The cuticular folds of convex epidermal cells display declining water retention on the outer petal surface and the exposed side of the corolla to the environmental conditions. The cuticular folds of papillae epidermal cells increase in size the inner petal surface, in comparison with the outer surface; such traits facilitate light absorption and enhanced the contact area among folds and curvatures at the inner side of the corolla. It appears that nanometric surface structures of petals may be important adaptive features of C. japonica flowers, contributing to their performance in the field.