Eucalyptus leaf. Coloured scanning electron micrograph (SEM) of a section through a leaf from a lemon eucalyptus tree (Eucalyptus citriodora). The oil cavities (brown) secrete the oil that gives this eucalyptus tree its name. Covering the surfaces of the leaf are layers of crystalline wax (white). The lemon eucalyptus is an evergreen tree. Magnification: x110 at 6x7cm size.