Why don’t some flowers smell?

Some people assume that all flowers should have a perfume. They imagine that a flower with no scent is an older flower, whose fragrance has evaporated. But that may not be the case. A flower with a fragrance is a flower with a mission. Flowers emit fragrance for genetic reasons — specifically, to attract a pollinator such as insects, birds, bats, and other mammals. These creatures transfer pollen from one flower to another on the same plant, or to a flower of another plant of the same species. Flowers without a fragrance depend on self-pollination. In self-pollination, there’s a transfer of pollen from the male stamen to the female stigma of the same flower. Most flowers with a fragrance are what are called “generalists.” Any number of different creatures can serve as pollinators. But there are some plants that emit a fragrance to attract a specific creature. For example, the common yucca – found throughout the southwestern U.S. – attracts only the yucca moth. Researchers still don’t ...  more