What's that heady fragrance drifting on the air at dusk? Cinnamon, nutmeg, nectar...scents that emanate from an oriental lily or lilac or honeysuckle. What's a garden without those wonderful scents? But have you ever wondered how and why flowers smell the way they do?
Theory has it that flowers produce scents in order to attract insects to potential food sources. Another line of thought centers on insects seeking mates which are attracted to specific flowers. Researchers can only surmise this, as no one really knows how insects detect scent, but the pattern of specific insects revisiting specific species of flowers pretty much clarifies the idea. The cross-pollination cycle is completed by the visitation of these insects. And yet another theory is that the scents are also meant to deter herbivores such as deer and rabbits. Certain fragrances attract specific species of insects; for example, the Carrion flower (Stapelia giganteum) stinks like rotting flesh and, therefore, attracts beetles and flies.
Flower fragrances are chemical in nature, or evolve from chemicals produced by cell membrane metabolism. Lovely jasmine's perfume is methyl jasmonate, while wintergreen's fragrance is methyl salicylate--related to aspirin. Freshly-mown grass gives off its distinctive aroma as a result of cell membrane derivatives such as ketones, aldehydes, and alcohols. A flower's fragrance can be from pollen or from different parts of the petals or pistils, or from both sources.
Many trees and shrubs have minimal flowering, but lovely scents, and some foliage plants can hold their own with crisp, herbal fragrances like the Peppermint Scented Geranium or Sweet Woodruff.
Enjoying Fragrance in Your Gardens
Selecting plants that have known fragrant qualities is the first step in filling your personal environment with lovely scents. A long list of scented flowers, trees, and shrubs follows.
Locating those plants in the perfect spot is the second step. Since the production of fragrance is often tied in with a circadian cycle, you'll want to plan where you will get the most enjoyment from a specific flower. For instance, Flowering Tobacco (Nicotiana) releases its fragrance at night to attract the moths that pollinate it, so place Nicotiana near an open window, or if you spend time outdoors in the evening, position it accordingly. Snapdragons (Antirhinnum majus) are highly scented during the day when bees are active. Locate snapdragons in with other flowers to take full advantage of their advertising.
Providing sufficient nutrition, warm temperatures, and high light will ensure that your flowers produce more fragrance.
While highly fragrant flowers are a delight, the plant's production of scent reduces the life of the flower. Commercial breeders have considered shelf or vase-life over fragrance, and have focused on breeding out that element. In an article for University of Minnesota Extension, Charlie Rohwer states, "...cyclamen used to have a fragrant flower. However, breeding programs have ignored fragrance, so it has been virtually bred out."1 (It seems a shame that such beautiful flowers have no scent.)
A List of Fragrant Flowers, Shrubs, and Trees
This list is by no means all-inclusive, as many fragrant species flourish all over the world. Be sure to check if a species is considered invasive in your particular region.
1 "Understanding Flower Fragrance," Charlie Rohwer. University of Minnesota Extension, Yard & Garden Line News, Vol. 5, No. 1, January 1, 2003.
The Helpful Gardener. http://www.helpfulgardener.com
About Toni Leland
Toni Leland has been writing for over 20 years. As a spokesman for the Ohio State University Master Gardener program, she has written a biweekly newspaper column and is the editor of the Muskingum County MG newsletter, Connections; she currently writes for GRIT, Over the Back Fence, and Country Living magazines. She has been a gardener all her life, working soil all over the world. In her day job, she scripts and produces educational DVDs about caring for Miniature Horses, writes and edits books about them, and has published five novels.