Bite into a ripe tomato and your mouth fills with the joyous taste of summer. A little sweet, a little acid, still warm from the sun that ripened it, a really great tomato needs nothing more than a bit of salt and pepper. I am happy eating tomatoes in the garden without even that, right out of hand. Off the vine and into the mouth, nothing could be better.

Well, but then there is the tomato sandwich — with just mayonnaise, salt and pepper on chewy, crusty bread. And tomato soup, chilled, with a dollop of sour cream. Not to mention fresh salsa, the sweet tomatoes a cooling backdrop for the heat of the chilies. And tomatoes roasted with olive oil, garlic, and herbs until dense and caramelized. And maybe, best of all, fresh tomato pizza. Bubbly mozzarella, hot juicy tomatoes, salt, pepper, and chopped basil. Nope, nothing could be better than that!

It wasn't until tonight that we managed to have our first fresh tomato pizza of the season. We polished off one pizza between us, and I made the error of leaving the second out on the counter as a hedge against a post-column-writing hunger attack. Visiting the kitchen later, I found only a dusting of cornmeal on the counter, and a large content black dog with tomato breath. She likes to remind us that the good things in life are better shared and, of course, she is right.

Our first tomato pizza, usually a midsummer ritual with us, came late this year partly because we have been crazy-busy, but mostly because this is a late year for tomatoes. A rainy July in Indiana meant that they've been slow to ripen, and these wonderful summer vegetables are just now coming into their own.

(Vegetables, you ask? Isn't the tomato really a fruit? Well, yes, it was until 1893, when the Supreme Court, in Nix v. Hedden, ruled that since the tomato is cooked and served like a vegetable as a main part of the meal and not as a dessert, it's a vegetable regardless of its botanical classification. Because the justices had never ended their meal with a luscious green tomato pie or a sweet tomato sorbet, poor Mr. Nix, a fruit importer whose wares were normally duty free, had to pay the vegetable tariff on his tomatoes. And you thought the Court just decided presidential elections!)

But tomatoes, be they vegetable or fruit, are here at last, and it is worthwhile taking a little time to search out the very best. Not that there is anything wrong with any good home grown tomato, but the real wonders of the garden are the heirlooms.

Heirloom tomatoes are open pollinated tomatoes that have been grown from seed saved from earlier crops. (Hybrid tomatoes, in contrast, do not reliably produce offspring like themselves.) Some people maintain that to really qualify, heirloom seed must be passed from generation to generation like a precious family quilt.

Once upon a time, all seed was "heirloom." Most people grew their own vegetables, or bought them from someone who grew them. Fresh tomatoes were eaten when they were in season, and dreamed about when they were not.

But in the 1940s, the market began to change. People wanted vegetables whether in season locally or not, and as they moved to cities they got farther from the farm in more ways than one. Shopping in grocery stores for imported vegetables, they forgot that a good tomato could be misshapen and cat-faced and still taste wonderful, and they began to prefer uniform, picture-perfect year-round fruit.

All of which meant that the seed companies stopped selling commercial heirloom seeds and went to work creating hybrids that could provide a dependable crop for farmers, be shipped without damage, have a long shelf life, and look good to consumers. The result? That rock hard, anemically pink, absolutely flavorless tomato you can find all year in the grocery store. Whatever an heirloom is, this is what it is not.

Even if the label on that supermarket tomato says "vine-ripened," there is no official regulation that says it must be so. More likely it was mechanically harvested in some still-green stage in a far away place, loaded onto a truck, and treated with ethylene gas to turn it red in transit. The claim is that the gas ripens the fruit, but really, I think, it just turns a green-colored green tomato into a red-colored green tomato. Certainly what arrives in the store does not explode with tomato flavor, or any flavor at all.

Good tomato flavor (and vitamin C content, by the way) comes from the natural ripening process. Real ripening takes place in the heat of the sun, preferably when the tomato is still attached to the vine, when the sugar develops to offset the acid, and that splendid, mouth-stinging, heart-singing tomato taste comes out. You can't get this in Indiana in the non-summer months. Period.

That doesn't stop the seed companies from developing seeds for imposter tomatoes. Even the hybrids for home growers, delicious as some of them may be, are still designed for easy growing, for uniformity of size and shape, for resistance to disease, and for beauty. They are not, simply and finally, all about taste.

In 1975, alarmed that the old fruit and vegetable strains were disappearing in the onslaught of hybrids, Kent and Diane Whealy started the Seed Savers Exchange (SSE, now online at seedsavers.org.). SSE encourages people to grow and distribute the heirloom varieties of fruits, vegetables, grains and berries developed on this continent by Native Americans, and Mennonite and Amish communities, or imported by immigrant families. They estimate that members of their nonprofit organization have distributed more than 750,000 samples of seeds since their founding, and they lead a now extensive movement to return flavor, character, and heritage to our diets.

Over 1,200 varieties of heirloom tomatoes alone have been documented and preserved, and they are the jewel box of the garden. Purple with green shoulders, bright yellow, green striped, streaky orange, blushing pink, or deep red. Smooth or ruffled, shaped like plums, cherries, lemons, pears and hearts. For all their gorgeous variety, what heirloom tomatoes almost always have in common is their spicy scent and luscious flavor, and the promise that their season is all too short.

Several vendors at the Bloomington Community Farmers Market sell heirloom tomatoes on Saturdays, though you may need to be there early to get them. If you'd like to see some on the vine, as it were, take a stroll through the Hilltop Garden and Nature Center's Summer Youth Garden. All the tomatoes grown by the kids are heirlooms, and their garden is a funny, lush, and happy place for an afternoon walk. They are open to the public Monday through Friday, 1-5. See Hilltop's Web site at http://www.indiana.edu/~hilltop/.

Christine would love to hear from you. She can be reached by e-mail at cbarbour@heraldt.com. Food Fare partner Jennifer Piurek, mindful that IU is back in session, will offer some big sister advice on the "freshman 15" problemand how to keep the pounds off when you're away from home for the first time.