Flavorings Are Chemical Weapons

And why are some plants’ parts especially potent, intense sources of flavor? What role do the chemicals that give them their flavor play in the lives of the plants themselves?

One simple clue is their very potency. Try the experiment of chewing on an oregano leaf, or a clove, or a vanilla bean. The result is far from pleasurable! When eaten as is, most spices and herbs are acrid, irritating, numbing. And the chemicals responsible for these sensations are actually toxic. The purified essence of oregano and of thyme can be bought from chemical supply companies, and come with bright warning labels: these chemicals damage skin and lungs, so don’t touch or inhale. This is precisely the primary function of these chemicals: to make the plants that produce them obnoxious and therefore resistant to attack by animals or microbes. The flavors of herbs and spices are defensive chemical weapons that are released from plant cells when the plant is chewed on. Their volatility gives them the advantage of counterattacking through the air, not just on direct contact, and of being a warning signal that can train some animals to be deterred by smell alone.