Take peppermint for example. Peppermint is distilled from the whole peppermint plant and is sourced indigenously from the northwestern United States. The ratio of the constituents menthol to menthone is used as a marker for high quality peppermint oil. Certified Pure Therapeutic Grade® peppermint oil should always have a significantly higher proportion of menthol because menthol has been shown to improve the beneficial value of peppermint essential oil. One study tested the cleansing properties of peppermint essential oil from three different species. Peppermint from Mentha piperita was demonstrated to have the highest cleansing properties, which was attributed to its high amount of menthol and low amounts of menthone. Conversely, the Mentha aquatica species was shown to have significantly lower cleansing properties and also had a lower amount of menthol and a higher amount of menthone. (Mimica-Dukić N, Et Al. 2003)

As for being the “heartbeat of the plant kingdom,” Most plants don’t even produce essential oils so where is their heartbeat? I am not really sure what that statement is supposed to mean, I guess somebody just thought it sounded marketable and ran with it. Concerning the “life blood” claim, as I have said here before, essential oils do not have the same function in the plant that blood does in the human body. Our blood primarily performs the function of circulation and transport of oxygen and nutrients to the all the cells and organs of the body. Essential oils do not play this role in the plant.
Essential oils are generally extracted by distillation, often by using steam. Other processes include expression, solvent extraction, sfumatura, absolute oil extraction, resin tapping, wax embedding, and cold pressing. They are used in perfumes, cosmetics, soaps and other products, for flavoring food and drink, and for adding scents to incense and household cleaning products.