Finding essential oil from plant part

Essential oil is produced from various part of plant and then stored in various organs. Research shows that they are made in the certain organs. They are present inside the plant (called "internal glands") and outside it (called "external ones").
Internal gland
It is produced by the entry of essential oils that originally exist outside the cells, which then destroy them around it, create a kind of channel organs with essential oils inside. There are possibilities that the surrounding ones to dissolved and create a group of cells called "glands" thus produce a channel that contains it.
Its mechanism such as formation schizolysigen. Some of them may exist in all parts of the certain trees. There are herbs that contained it only in the leaves, flowers, or in the trunk. There are also trees that contain it in some location of the plant, for example in the leaves and the bark as in Cinnamoni (cinnamon). Under microscope, it appears that they exist in the form of fraction with slightly yellowish-colored cells. Sometimes their wall dissolved to build a line of volatile oil in cinnamon bark (created by schizolysigen).
External gland
Glands of the external surface, commonly referred to as "epidermal cells" or its modification, such as hairs. The volatile products are usually buried in between the cuticle (outer layer) and the wall between a cell with others. Cuticle in the form of a thin layer will rupture when exposed to friction, eg friction hands. When the cuticle breaks, they would come out so its smell will spread.
Under microscope, that hairs found on the entire surface of the leaves and bark. They shaped like hair and a sphere-shaped organ that contain the volatile compounds. Important things to note:
1. In the Cinnamomun zeylanicum BREYN, it is found in the bark as opposed to that contained in the leaves.
2. In Coniferae, it is found in all plant parts.
3. In rose, it is found only in the petals of flowers.
4. In Umbelliferae, it is in pericarp of fruit.
5. On citrus (orange), it is in the petals and its composition is very different with the volatile compounds which come from the peel of the fruit.

If you want to produce essential oils, you need to know the parts of plants which can produce it. So it should be studied first.

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