Flowers: Those beautiful deceivers

By Gary Raham
Writer and Illustrator

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Flowers: We plant them, press them, give them to blushing brides, use them as peace offerings, adorn our hair or lapels with them, and may even use them (along with birds and bees, of course) as the classic metaphor for sex education with our children. But can you trust them? Flowers can be seductive and sometimes dangerous deceivers--especially for their target audience: the insects.

Free lunch flowers

Primitive flowers, existing in the days of the dinosaurs, may have offered a scented buffet table open to all comers, hoping that some visitors would carry their pollen to the right place. Cow parsley, Queen Ann's lace and wild carrot, along with flowers in the daisy family practice this approach today. A wide variety of beetles and flies--some of the most primitive insects--cavort willingly on such flowers.

Bee flowers

Bees and flowers share a mutually beneficial relationship of long standing. Bee-pollinated flowers tend to be open in the daytime, have a minty fragrance and offer nectar, pollen or both as rewards. They are brightly colored and often have markings called nectar guides (some only visible in UV light, which bees can see) that point bees toward the food locker. Many, like snapdragons, have handy landing platforms. Bee plants include sages, mints, vetches, legumes, clovers, foxglove and others.

Flowers as victims

The animal chauvinists among us might think that any balance of power between flowers and insects might tilt to the advantage of insects. Some beetles, hover flies, small bees and ants do make away with the groceries without giving anything in return. Some beetles and nectar-feeding birds will chew or poke holes in the sides of flowers like penstemons to raid the larder for free. But flowers have a few tricks up their petals to gain revenge.

Mimicry

Some plants produce flowers that look like a common species that already has reliable insect pollinators. A rare Mideastern orchid, for example, looks much like a bee-pollinated herb, but has no nectar. Some bees lose out.

Other plants attract flies and carrion beetles by mimicking the scents of rotting flesh and feces. One 8-foot tall plant from Sumatra does such a nice job of imitating rotting fish that men have been known to pass out if they take too big a whiff.

Certain species of tropical orchids look exactly like the underside of mushrooms - enough to attract fungus gnats, which aid in the orchid's reproduction. Another kind of orchid sports wart-like structures on its petals that look like clusters of flies, attracting other party-loving flies. A third kind produces aphid-like bumps on its petals that attract hover fly predators.

The most ironic flower trick?

Look sexy. A French biologist spent 20 years carefully documenting wasps making out with flowers so he wouldn't look like a fool in print. Normally Thynid wasps find their wingless mates on plant leaves and fly off with them to mate in the air. The hammer orchid provides a mate look-alike on a long, hinged floral arm. When the male swoops down to capture his paramour the hinged arm flips him over against the flower's pollinia and stigmatic plate. Two mistakes by the male pollinates the orchid.

Trap, ambush, murder

Flowers have found many ways to trap beetles. Certain water lilies may open one afternoon with an inviting smell and beetles enter. The flower closes at night and the beetles thrash around, getting pollen-coated in the process. Next morning, the flower opens (with almost no odor) and the beetle moves on to the next ready flower.

Water lilies in the genus Nymphaea have a darker tale to tell: They produce pollen-loaded stamens that stick up like sweet-scented lollipops, drawing flies, beetles, bees, hoverflies and other insects. The female flowers open, but all they contain is a pool of water in the center with a wetting agent that helps insure that any clumsy insect that falls in will drown. The pollen on their bodies eventually drifts to the bottom of the pool and fertilizes the female flower.

Other flower exploitees

Flowers also attract birds and bats with their nectar and pollen. They entice mammals like the Australian honey possum and the Namaqua rock mouse with sweet nectar.

And, if you're reading this article, flowering plants probably have you right where they want you--under your green thumb, which you are using to bury their bulbs and cast their seeds upon your garden.

Don't feel too persecuted. Enjoying their smell and seeing their spring glory seems like a fair return on investment.