The Importance Of Smell

©Marlene Condon

January 2, 2021

Humans are often not aware of how important their sense of smell is until they lose it, or it is somehow diminished. When you have trouble smelling, you quickly realize that your sense of taste is affected, which can make food much less appetizing. It can cause you to lose interest in eating, something that is not uncommon in older folks who may become malnourished as a result.

Many forms of wildlife are also very dependent upon their sense of smell in order to stay well nourished. The group that contains the most numerous kinds of animals that rely on this sense is undoubtedly that of the insects.

You may be aware that fragrant flowers evolved in order to attract insects (and sometimes other creatures, such as nectar-drinking bats) to them for pollination. This is especially evident in those flowers that open during the hours of darkness or late in the day and remain open all night.

If you have ever grown the original, old-fashioned Flowering Tobacco (Nicotiana alata) or Large Moonflower Vine (Calonyction aculeatum) and you walked near the plants after the flowers had unfurled their petals, you should have noticed the strong perfume they give off. In fact, these plants are often sold with other nice-smelling flowers to create a “Fragrance Garden.”

Although Flowering Tobacco blossoms open early enough for hummingbirds to visit and help with pollination, the flowers of Moonflower Vine usually open so late that night-flying nectar-seeking insects are the main pollinators.

Sometimes the fragrance given off by blooms is not particularly noticeable to humans because our olfactory senses are not sensitive enough to detect the molecules that are wafting through the air. However, if you place your nose up close to a blossom, you may be able to detect its scent.

I find Common Evening Primrose (Oenothera biennis) wildflowers enchanting because the flowers open quickly enough at dusk that you can watch the petals spread apart. When I first observed the unexpected movement of these blooms, I was delighted; the whole process just seemed so magical (I have a scientific mind, but also a little girl’s heart).

Sphinx moths arrived very quickly at the newly opened blooms, which surprised me. Astonished that the moths had found the flowers so fast, I wondered if they were detecting an odor I had not while standing near the plant. I bent over, put my nose right up to the blossom, and sure enough, a subdued perfume was being released by the primrose.

Of course, this result is not conclusive. The sphinx moths may have detected the yellow blossoms by sight, or they may have used a combination of both sight and smell in order to zone in on this source of food. Whatever the answer, the natural world is full of surprises for us to notice, assuming we look!

Common Evening Primrose can easily be seen in Virginia, growing alongside highways and byways, and even in your yard if you allow “volunteer” plants to join your garden specimens.