- Out of the nearly 4,50,000 species known to mankind , about 2000 species, which come from about 60 botanical families, contain essential oils. The families-Pinaceae among the gymnosperms, Apiaceae, Myrtaceae, Rutaceae, Lauraceae, Lamiaceae, Asteraceae (dicots), Poaceae, Aracaceae, Zingiberaceae and Amaryllidaceae (monocots) among the angiosperms, account for a large number of plants bearing essential oils of commercial importance.
- The volatile oils occur in varied parts of the plant anatomy-in some cases being found all over the plant body, in others being restricted to one special portion of the plant. Thus, in the conifers, of which the pine is a type, volatile oil is found all over the various parts; whereas in the rose, the oil is confined to the petals; in cinnamon, to the bark and the leaves; in the orange family, chiefly to the flowers and the peel of the fruit; in aromatic grasses and mints, to the leaves, in ambrette, cumin, fennel, etc, in seeds and in vetiver in the roots. In plants, these essential oils are produced in specialized glandular cells. In the case of the leaves and petals, the essential oils are contained in the innermost membrane of the cell-wall in parenchymatous tissue. In other plants, they accumulate as floating drops in the protoplasm (e.g.terpenes in orange peels) or in separate cell cavities.
|
Participants