Depending on the species the essential oil is stored practically in all plant parts. In some species the essential oil is stored in more than one plant part and the composition may differ e.g. cinnamon (the leaf oil contains eugenol as the major components while the bark oil contains cinnamaldehyde as the principal constituent). In some species the oil is stored in only one part e.g. vetiver roots. Within the plant or plant part, the essential oil is stored in one of these specialized structures: oil glands or glandular trichomes of diverse sizes and shapes, idioblasts, cavities, channels, heartwood (e.g. sandalwood) etc.