Lemon peel. Coloured Scanning Electron Micrograph (SEM) of zest" cells in the peel of a lemon, Citrus limoni. 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 lemon peel its tangy flavour. The essence obtained from the peel is used extensively in the perfume industry. Magnification: x30 at 6x7cm size. x74 at 8x6",x40 at 10x7cm master size"