Orange peel. Coloured Scanning Electron Micrograph (SEM) of zest" cells in the peel of an orange, Citrus sp.. In this section the zest cells have been cut across and appear as the round, concave orange structures. These structures are specialised epidermal cells known as trichomes. They are glandular, secreting the oil which gives orange peel its tangy flavour. Magnification: x28 at 5x7cm size. x74 at 8x6",x40 at 10x7cm master size"