Why Your Roses Smell Nice

The appeal of many floral scents to humans is a fortunate byproduct: We were not even around when they appeared. And, for all the effort, commercial perfumes rarely smell like flowers. Expensive, fancy bottles labeled jasmine or gardenia may smell wonderful but they are sad substitutes for the real thing.

One reason is that flowers generally produce very large mixtures of different volatile molecules, as many as a thousand. Some of these fall into related chemical groups and although they differ very slightly in chemical structure, they can produce very different smells. In closely related flowers, the volatile molecules can vary both in relative amounts (reflecting differential regulation of the genes and gene products needed) and in their chemical structures (reflecting the activity of genes evolved to produce the enzymes needed for synthesis). It’s not easy to figure out which components of a mixture are important for attracting insects or birds or for achieving a perfume attractive to people. It is especially challenging because our own sense of smell depends on a complex set of nerve cells and often differs from one person