A scent produced by plants serves two purposes: it attracts pollinators or deters those organisms which constitute a threat for vegetation. For the animal, the attracting scent is a promise of nutritious nectar. Pollen transferred via the hungry guest enables plant reproduction. The second reason of fragrant properties of leaves, stems or roots is deterring plant parasites, fungi and microorganisms. Fragrant essential oils contained in plant tissues destroy pathogens and, as they are usually sour, negatively influence the taste and discourage animals from consuming the plants. That is why plants containing strong aromas have healing, fungicidal and germicidal properties.
Humans, like other animals, possess the ability to distinguish between scents and memorize them. Their number can be enormous and the memories recalled by scents can constitute for us a travel many years back in time.