Types of Florin rings, distributional patterns of epicuticular wax, and their relationships in the genus Pinus

Abstract

The shape of Florin rings and the distributional patterns of epicuticular wax of 51 species, including three varieties, in the genus Pinus were observed and classified with a scanning electron microscope. Six types of Florin rings and three types of wax distribution were observed. Florin ring structures and wax distribution correspond to subgenera. The restriction of the epicuticular waxes to the needle surface on which stomatal complexes occur suggests that the wax originates in association with the stomatal complex. In the subgenus Pinus, the Florin ring with a small opening size had little wax in the epistomatal chamber; the Florin ring with a large opening size had large amounts of wax. This suggests that the amount of wax in the epistomatal chamber and the opening size of the Florin ring are correlated with gas diffusion. Common thin, fibrillar wax, rare thick, winding wax, and occasional amorphous wax were observed. The relationships among the types of Florin rings are further discussed from the viewpoint of a developmental process.