Leaf oil glands. Coloured scanning electron micrograph (SEM) of leaves from a thyme plant (Thymus vulgaris). A flower bud is seen between the two leaves. Two types of leaf trichomes (hairs) are seen. The smaller, spiky, hairs may have a protective function or reduce evaporation from the leaf. The flattened structures (blue) are modified glandular hairs that are the source of the aromatic oil of thyme. Thyme is used as a herb in cooking. It also has medicinal properties. Magnification: x46 when printed 10cm wide.