I was prompted to write about this by some of the aromas I noticed walking through the allotments yesterday evening. Essential oils play a vital part in a plant’s survival as a species. Some such as the hot oil found in Horseradish root are designed to stop less perverse species than humans from eating it! The same is true of the Chilli Pepper. (My love of both clearly places me high up in the perversion stakes!)
Others, particularly those given out by flowers are designed to attract pollinating insects and the amount of the essential oil varies throughout the day. Night scented stocks and Honeysuckle give out more of their oils in the evening, reflecting the fact that they have evolved to be pollinated mainly by moths and other night flying insects. This is also an indication of when peak nectar production occurs.
Other plants such as rosemary are visited by the bees more in the morning than the afternoon though only when the temperature gets warm enough and yet others such as lime, (linden blossom rather than citrus) peak in the heat of late summer afternoons.
Yet others like the Hawthorn are more difficult to pin down. Over the past few days the tree in our garden has been buzzing literally with bees. I can hear it from several metres away. Yet according to the books, they only produce a honey crop in some years and researchers have been unable to pin this down to any particular weather conditions. It could possibly be something influenced by weather conditions the previous year.
There are many more example of plants and trees that are frequented by insects at particular times of day and for some it is a visual thing that attracts the insects that see almost exclusively by ultra violet light rather than any essential oils that might be produced. Many vlowers viewed under a UV light will demonstrate a pattern normally invisible to us that guides the bee or other insect to the nectar source, ensuring that it spreads the pollen about either within the flower or carrying it to other flowers to enable seed production.
For myself, much as I love working with essential oils from bottles, there is something about smelling them directly from the plant and especially when a waft of something reaches my nostrils, tracking down which plant or tree it comes from. It is not always one I know from a bottle so I then wonder why not? Lilac for example is only available as a perfume or fragrance oil. The essential oil costs over £20/ml and has only recently become available by CO2 extraction and still does not match the scent of the flowers. So note that while many are available beware and do your research before buying. Also enjoy the scents where you can in their natural environment. The psychological benefits of these scents come largely from their interaction in the brain and it is through breathing them in rather than absorption through the skin as in massage that they reach the brain most quickly.