The pollinator-flower relationship

During the warmer months when flowering plants are putting on a big show, many gardeners enjoy watching birds, butterflies and bees visit their gardens. But what is it about these flowers, exactly, that draws these beneficial pollinators to the yard? The answer lies in co-evolution. Flowers have evolved over millions of years alongside their particular pollinator, be it a bird, bat, bee, butterfly, beetle, wasp, fly or other creature. To encourage those species to visit, flowers took on specific characteristics that appeal to their particular pollinator.

An insect is drawn to a flower, proceeds to root around for nectar or pollen to eat, then moves on after finding its reward. As it forages, the bird or insect inadvertently collects pollen, which is then spread to other nearby flowers, helping the plant reproduce. The shape and color of the flower, as well as the presence or absence of a scent, is a big clue to the type of pollinator that will come to visit.

Birds have excellent daytime vision but a terrible sense of smell, so many birdpollinated plants are bright red or orange but scentless. The most common bird pollinator is the popular and energetic hummingbird, which seeks tube-shaped blooms to probe with their long, proboscis-like beaks for deeply buried nectar. Recommended plants: agastache, columbine, native honeysuckle, lobelia, penstemon and salvia.

Bees, including honeybees, bumblebees and our myriad other native bee species, see the world in a different light: they can perceive ultraviolet (UV) light. They are especially drawn to lightly scented blue, purple and yellow blooms, many of which also have a pattern of lines that serve as “landing stripes” to steer visitors in for a visit. Bee-friendly flowers are typically sturdy: consider snapdragon blooms, which only pop open when visited by hefty fellows like bumblebees.

Recommended plants: borage, monarda, coneflower, hosta, fall asters, goldenrod. Butterflies, like hummingbirds, are also drawn to tube-shaped flowers in red, orange and purple color schemes. Scent and color are less of a factor than the flower’s shape, as butterflies love to seek out nectar deep inside a vessel that precludes other insects from accessing the reward there. Recommended plants: bee balm, coneflower, milkweed (Asclepias), joe-pye weed, phlox, asters, goldenrod.

Photo courtesy Wikimedia Commons

Goldenrod is one of many pollinators that connect insects and plants, which leads to the survival of both species. Moths are mostly nightfliers, and are heavily drawn to white or pale-colored flowers with a strong, sweet scent. Recommended plants: angels’ trumpet (Datura), flowering tobacco (Nicotania), hosta, soapwort, valerian and yucca.

Bats, yes bats! While they’re best known as voracious insect-eaters, bats also serve an important role in pollinating night-blooming flowers and like moths, are drawn to pale flowers with a sweet scent. In our area, bats do dine mainly on insects, but in warmer zones, they are responsible for most of the pollination of tropical fruits like banana, guava, cocoa and agave. No bats, no tequila. Beetles often get a bad rap, but they actually do more heavy lifting than the media-darling bees.

Because of the sheer number of species —over30,000inthe United States alone — beetles are thought to pollinate almost 90 percent of the world’s flowering plants.

They are especially attracted to open, bowl-shaped flowers or tight clusters of flowers, usually lightly scented and pale in color. Recommended plants: magnolia, pond lily, paw paw, goldenrod.

Nature Note for 8/24/14