This is the question posed by "The Great Pollinator Partnership," an exhibit on view inside and outside the U.S. Botanic Garden. The fertilization of plants is among the many natural phenomena that suggest Rube Goldberg played a key role in evolution. Consider that the joining of male and female sex cells depends on the intervention of a third party -- the pollinator. A pollinator can be a force of nature, like wind or water, or, more often, an animal, such as a hummingbird or honeybee. (There's a reason the phrase "the birds and the bees" is a euphemism for the mechanics of reproduction.)

Like the symbiotic relationship it celebrates, "The Great Pollinator Partnership" has two parts -- "Dynamic Duos: Plants and Pollinators," a small photography exhibit in the West Orangerie, and "Dancing With Flowers: The Pollination Connection," 12 botanical displays outside on the garden's terrace. Each outdoor exhibit features a cluster of plants pollinated in a different way, whether it be by insects ("The Butterfly Garden"), the weather ("The Wind Garden") or black-and-white ruffed lemurs ("The Unusual Pollinators Garden").

The subjects of the show come and go as they please, literally animating the botanical displays. (The same degree of mobility in an art museum might cause a Van Dyck to appear unexpectedly among the Pre-Raphaelites or a Cezanne to turn up in the Italian Renaissance gallery.) On a recent visit, bees and butterflies crowded "The Wasp Garden," while wasps congregated in "The Hummingbird Garden." A scruffy urban robin perched atop exhibit signage in "The Unusual Pollinators Garden," while a monarch butterfly hovered above "The Beetle Garden." Sticklers noted, however, that "The Solitary Bee Garden" did, in fact, contain a lone bee.

Along with clouds of winged visitors, each garden includes explanatory text about the pollinators in question. "The Unusual Pollinators Garden," for example, explains how nonstandard pollination can result from what are essentially bad table manners. New Zealand flax is pollinated by geckos, who smear the pollen on their chins while probing blossoms. The same is true of lemurs in Madagascar and honey possums in Australia -- pollinators all. In one extreme case, the Brighamia insignis, a plant native to the mountains of Hawaii, has no natural pollinators left. Human volunteers rappel down cliff sides to do the job.

Many of the gardens explore what you might call flowers' architectural characteristics. In "The Beetle Garden" -- suffused with the intoxicating smell of magnolia -- visitors learn that the tree's blossoms are highly desirable residences. Their broad, loosely spaced petals make it easy to move around. "The Butterfly Garden" reveals that the insects alight on flowers with clusters of small blooms for a practical reason: They constitute a relatively flat landing surface. As for aesthetics, they prefer a nursery palette of pink, light blue, yellow and white.

But pollination isn't all monarchs and magnolias. "The Fly Garden" notes the lengths to which plants will go to attract the insects. Some smell bad, some have a "meat-like" color and some have protrusions that resemble fur. "The Wind Garden" suggests that visitors pause between sneezes to consider the virtues of wind-borne pollen, which pollinates 12 percent of the world's flowering plants. It may seem like a small percentage, but it includes food crops such as wheat, corn, rice, barley, oats and rye. Pollination by wind is not as efficient as pollination by insects, which is why these plants release so much pollen into the air. Nor do they redeem themselves with pretty flowers: Plants pollinated by the wind don't need such displays to attract pollinators, so they are typically "pale, green and small."

The photo exhibit inside elaborates on the points made outside and provides closer looks at the pollinators. Much closer. A picture of a honeybee on a pasqueflower captures each individual pollen speck on each individual bee hair -- it looks something like your cat would if it rolled in talcum powder. A broad-billed hummingbird sips from a snapdragon like a fairy in a 19th-century children's book. A paper wasp has eaten its way so far into a penstemon flower that all you can see is its butt hanging out the back. In many cases, the photographs complement the gardens. On the terrace, visitors see black-eyed Susans and learn that the flowers have markings visible only to bees. A photograph indoors captures a black-eyed Susan under UV light, providing a "bee's-eye view" of the bloom.

Some of the photographs were taken with scanning electron microscopes. There are images of structures as impossibly small as the seam supporting a honeybee's wing. Other photos -- all spikes and plates like medieval armor -- capture the insects' eyes, antennae and "knees." (You've heard the expression "He's the bee's knees"? Turns out it's not a compliment.) There's even a series depicting pollination on a microscopic level.

"The Great Pollinator Partnership" was co-sponsored by the North American Pollinator Protection Campaign, a coalition of more than 100 organizations that hopes to raise public awareness of threats to the "essential ecological phenomenon" that is pollination. Chief among them is habitat loss, followed at a distance by pesticides, pollution and invasive species. Though the exhibit has an agenda, you certainly can't call it a hidden agenda. A placard outside reads "Global Action Is Required" in letters two feet high. Wall text and handouts spell out things that visitors can do to help: These include everything from buying organic produce to putting out salt licks for butterflies and bees.

We need not look far for motivation to make our yards more attractive to pollinating insects. After all, 75 percent of the world's food plant species reproduce through pollination -- and, yes, that includes the coffee plant. Talk about a wake-up call.

THE GREAT POLLINATOR PARTNERSHIP -- Through Oct. 11 at the U.S. Botanic Garden, 100 Maryland Ave. SW. 202-225-8333. www.usbg.gov. Open daily from 10 to 5. Free. To learn more about the North American Pollinator Protection Campaign, visit www.nappc.org.

The leafcutter bee plays a crucial role in the fertilization of plants, but insects haven't cornered the market on pollination. Wind, water, hummingbirds and geckos are among the agents that keep the cycle going.