Comparative Anatomy on Leaves of Mezzettiopsis and Orophea (Annonaceae)

The leaf form and structure of 1 Mezzettiopsis species and 9 Orophea species were comparatively studied with the help of scanning electron microscope, epidermal maceration and paraffin section method. The results showed that there were three major anatomical differences between Mezzettiopsis and Orophea.In the leaf of Mezzettiopsis, each epidermal cell contained one cluster crystal, mesophyll tissue had one or two layer palisade tissue cells, oil cells were evenly distributed in the palisade and spongy tissue, and palisade tissue were non-contiguous in the leaf midrib. In leaves of Orophea, however, all most epidermal cells contained one oblique crystal, mesophyll tissue had one layer palisade tissue cells, oil cells were only distributed in the spongy tissue, and palisade tissue were contiguous in the leaf midribs. Therefore, the results mentioned above supported the viewpoint that Mezzettiopsis and Orophea were two distinct genera.