Sage leaf oil glands. Coloured scanning electron micrograph (SEM) of a freeze-fracture through a sage leaf (Salvia officinalis), showing hairs, or trichomes, (green, thin) and oil glands (red, round) in the leaf. The oil glands are modified glandular hairs that secrete the oils associated with the odour and essence of sage. Sage leaves are used in cooking and herbal medicine. Magnification: x35 when printed 10 cm wide.