If you were a rockfish or a rabbit or a robin, and if you wanted some romance, you could easily swim, hop, or fly towards a companion of the opposite sex.

But what if you were an apple tree or a carrot or an aster? Since you would be rooted to the spot, how would you get together with another member of your species to do what's needed to produce little apple trees, carrots, or asters?

Nature's answer is pollination. Pollination is, in fact, how plants have sex. It's by pollination that a flowering plant's male reproductive cells get transferred to a female reproductive receptacle. It happens with the help of the birds and the bees, as well as the bats, the flies, and even the wind. Without these "cupids," none of the world's flowering plants could reproduce.

Many plants that you wouldn't immediately think of as having flowers require pollination. Corn plants, oak trees and grasses, for example, each have a flowering period during which the wind pollinates them.

The National Zoo in Washington, D.C. recognizes the importance of pollination and this spring opened a 1,350 square foot exhibit devoted to it. If you ever find yourself in Washington, try to visit the exhibit.

If you do visit the exhibit, the profusion of butterflies would probably be the first part of the exhibit to catch your eye. At least 100 of them are fluttering around, seemingly everywhere. Most people have never been so close to so many of them, and the effect is lovely.

Their function in the Pollinarium is, of course, pollination. When a butterfly lands on a flower and sips its nectar, some of the flower's male sex cells (the pollen) will stick to the butterfly's body. When the butterfly visits the next flower, the butterfly

leaves some of the pollen behind on the female part of the flower.

With the butterfly acting as intermediary, the flowers have succeeded in getting their male and female sex cells together. If all goes as nature intended, the male and female cells will join together to produce seeds. The seeds then have the potential to produce baby plants.

One of the more fascinating exhibits that you can see at the Pollinarium is a larger-than-life model of a bat pollinating a night-blooming cactus. All night-blooming flowers, you'd learn, are white or light colored. The flowers have to be light-colored so that animals can see them at night.

One startling exhibit shows a life-size model of the rafflesia flower, with what looks like house flies near its center. The rafflesia is the largest flower on earth, measuring more than three feet across. It's not, however, a flower you would want to cut and keep in your house; the plant's odor resembles the smell of rotting meat. Flies just love it.

If you're lucky, you may see the hummingbirds hovering over flowers and sticking their long beaks into the blossoms to sip nectar. To hover, they need to beat their wings as much as a 100 times a second. The reason that they hover rather than perch is that the flower has no "ledge" for them or an insect to perch on. This is the flower's way of insuring that its nectar is reserved for hummingbirds. Otherwise, insects might visit, and they'd waste the flower's pollen by going to a different kind of flower on their next visit.

The Pollinarium is open Wednesdays through Sundays from 10 a.m. to 4:30 p.m. Admission to the National Zoo and the Pollinarium is free of charge.