On this week’s show, Vicki samples essential oils distilled from some of our favorite flowers. I even blended a few to make my own floral/herbal perfumes. Vicki’s favorites were one blend of lemon verbena, grapefruit and lemon skin oils; and a similar concoction with additions of rose, vetiver (made form the roots of a tropical grass) and cedar. The blends are surprising, and as long as the touches of citrus do not overpower, the blend smells more “fresh” than lemony.
Scent is about the most individual, alluring and mysterious aspects to plants. Until recently, scientists claimed that everyone smelled the same. I’ve never thought that to be true – not only do people have varying senses of smell; different fragrances are appealing or repellant to different people in varying degrees. And women detect and enjoy fragrances different than men. As Vicki reminds me, my acute sense of smell is a blessing and a curse (as a trip around the streets of New York on the day before trash pickup is all too clear).
There is still a bit of time left to acquire bulb with fragrant flowers: hyacinth, jonquil, even tulip – a flower usually described as “scentless.”
The sweetest of the daffodil relatives for fragrance is the species Narcissus jonquilla, the true jonquil. Where the paper white is heavy, the jonquil is delicate. There is a faint fragrance of the other daffodils, but with a cool honeysuckle note and the barest hint of lemon and spice. The jonquil reminds me of linen drying on the clothesline, with honeysuckle and a top note of sweet butter. (Sweet is a word we often use for fragrance, but sugar itself does not have a detectable scent since it doesn’t evaporate.)
How do noses and brains recognize scent? There are two divergent theories explaining how we detect and evaluate air-born molecules --“Shape” and “Vibration.” The differing theorists are engaged in a heated debate. One premise suggests that the shape of the molecules is recognized. Diane Ackerman (author of A Natural History of the Senses) describes the dominant acceptable explanation -- shape theory. Geometric connections between molecules and the neuron niches into which they fit help us analyze fragrance. So a wedge-shaped molecule fits into a V-shaped indentation inside the nose.
Chandler Burr’s book, The Emperor of Scent: A Story of Perfume, Obsession, and the Last Mystery of the Senses, documents scientist Luca Turin’s attempt to prove that we recognize odors primarily by their molecular vibration. The "vibrationists" see the nose like a spectroscope, an instrument that can dissect the atomic makeup of a molecule. Turin says we see color by vibration, hear music by vibration, and smell smells by vibration, too, and the nose is a biological spectroscope. Bear in mind that humans can taste only five flavors: sweet, sour, bitter, and salty, and the fifth flavor derived from the amino acid, glutamate, known to the Japanese as umami. However, we can analyze some 10,000 different smells. When we detect an essence, we are sampling the source, which gives a bit of itself away – as a blossom degrades or a bruised herb’s scented oil-filled cells burst. Not all flowers have odor, at least not accessible to humans, although some other creatures might recognize the scent. Flowers, after all, evolved fragrance to attract partners -- pollinators, and we are lucky to benefit by coincidence. Fragrance is a sacrifice plants make, and a gift to us gardeners.