Essential oils are concentrated plant essences. Although they are called "oils," this is something of a misnomer because most essential oils are not in fact oily, unlike vegetable oils which have been expressed from seeds or plant nuts (such as sesame, sunflower, peach kernel, and sweet almond). A few essential oils are rather viscous and others are fairly solid. Most, however, are watery, with lavender, lemon, and eucalyptus being classic examples. The color of essential oils varies, tending to be clear or yellow, although carrot is orange, spikenard is often green, and chamomile german a beautiful deep blue. Of course, essential oils are characterized most of all by their individual aromas - hence the term "aromatherapy."