There's some confusion among gardeners about old varieties of flowers and vegetables and even more confusion about hybrids.

Take flowers that are planted from seed -- things like sweet peas, zinnias, verbenas -- or vegetables like cucumbers, tomatoes, beans and so on.

And suppose you want to grow a variety of zinnia, say, from the 18th century. Well, the only way any such variety has been preserved is by saving seed, planting it, saving seed, planting it, and so on for a couple of centuries. What are the chances that over those centuries the flower has changed enormously? Suppose you wanted the ancient variety called 'Red Empress' (to make up a name for a mythical variety), and suppose gardeners had faithfully saved seed each year from that variety. You still would have no idea whether your 'Red Empress' is anything like the one of 1790.

Who knows how many bees over the years had brought foreign pollen to that variety, so that gradually the original characteristics of the variety were swamped by new genes. Or suppose that special care was taken to keep bees away, and the variety was self-pollinated over the years and you were fairly sure no new genetic qualities had entered the strain.

Even so, the variety might now be very different from the original. Somebody had to decide which flowers to save seed from. Would he save seed from the smallest flowers, or would he save seed from the largest and brightest flowers? A hundred generations of saving seed from the "best" blooms would result in a flower quite different from the one grown in 1790.

Or take a tomato. I grow one called 'Brandywine,' which is supposed to be more than 100 years old. My plants are more than eight feet tall now and they bear heavily and the fruit is possibly better than any other tomato, or possibly at least the equal of any other tomato, though the plant is not supposed to be resistant to any disease.

Well, mine have no disease. They don't even have hornworms or flea beetles or aphids. The fruit is almost globular, thin-skinned, superbly flavored, large, juicy, loyal, courteous, kind.

It is in shape and glory an utterly modern ideal tomato this year with me and I suspect it is altogether different from the original variety of that name. I suspect careful selection over the years has made it far finer than the first 'Brandywine.' If, indeed, there ever was an old variety of that name. The one now going by that name is superb, and that's enough for me.

But take a quite different tomato, a modern hybrid like 'Better Boy.' I find it excellent, though it would do you no good to save its seeds (as you might do with 'Brandywine'). For the hybrids like 'Better Boy' have to be raised anew each year from two quite different parents. It is only the particular combination of those two (unknown to me) varieties that results in seeds that will produce 'Better Boy.' If you save your own seed of that variety you will get an odd assortment of tomatoes, and perhaps not one of them will be at all like 'Better Boy' and most of them will be inferior.

It's a fact of vegetable life that sometimes when two fully distinct varieties are crossed -- that is, the pollen from one variety is dusted on the pistil of the other variety -- you will get seed that produces a plant of uncommon vigor, with qualities more desirable than are found in either parent. Heterosis, or "hybrid vigor," can in some cases give superior fruit with wonderful resistance to disease. But that assortment of wonderful qualities is found only in the first-generation cross of those two varieties, and unless you cross them every year you will not get 'Better Boy.'

The labor of hand-pollinating by the commercial seed grower every year, using only the two parents known to produce 'Better Boy,' is a major reason the hybrid seed costs more than seed of varieties that can be kept going indefinitely through self-pollination, without the seed producer doing anything at all.

At my place this year the non-hybrid 'Brandywine' is better than 'Better Boy,' but it might be a different story in another garden in another region. And suppose some tomato disease were introduced to my garden. Then all my 'Brandywines' might die in a matter of a few days, while all the 'Better Boys' would resist the disease and keep on producing excellent tomatoes.

Nothing in vegetable life is fully perfect. You may trade some small edge, some little excellence, in exchange for resistance to disease, resistance to early cold, resistance to heat (some tomatoes are more finicky than others when it comes to setting fruit in 90-degree days).

'Better Boy' is probably a perfect example of a plant in which very little (if anything at all) in the way of excellence has been traded for a lot of new virtues in disease resistance. But then 'Better Boy' was meant for home gardeners. It was not offered as a market variety.

Suppose you make your living truck farming, however. You might agree that 'Brandywine' is a superb tomato, but it does you no good if it dies of various tomato diseases. And it does you no good if its delicate thin skin breaks when you try to put it in boxes and truck it to market. It does you no good if it has to be picked fully ripe to display its superior qualities, whereas you the farmer have to pick your tomatoes green, letting them color over the days they spend in shipment and storage.

What you want, as a trucker, is a tomato with a thick skin and meaty exterior walls that resist the bruises of handling and shipping. You want a variety that colors blood red, even when picked utterly green. You want a tomato that will sit there without rotting for days on end. And when you find such a variety, you won't quibble too much if its flavor and texture are not up to 'Brandywine' or 'Better Boy.'

I personally will not eat pale, mealy tomatoes in restaurants. I scoop them out of salads and ask the waiter who the hell he thinks will eat such a tomato. On the other hand, some commercial varieties, while by no means the equal of the best dead-ripe home-garden varieties, are good enough to eat in a small way. They do not necessarily or always ruin a salad or a sandwich.

There is no such thing yet as a tomato that can be shipped about the country, trucked to supermarkets, dumped in bins and allowed to sit about for some days, that will also have the flavor of the best tomatoes. Housewives learned long ago that spaghetti sauce is much better made with good canned tomatoes than with inferior fresh ones at the store. Yet at the height of summer, at some groceries, if you're lucky, you can get quite good tomatoes, or at least good enough to prevent rioting in the streets.

The cost of raising superb quality tomatoes in the home garden can be considerable, if you have to buy or make tall cages for them to grow in, and have to protect the fruit with nets or wire mesh. If you go to that trouble and expense (and in most years you have to water them heavily once a week, and you have to have rich soil in full sun, which means you have to cut down on roses, irises and other plants that also demand the best spots in the garden) you are foolish to grow varieties bred for truck farmers. You could grow, for the same trouble, varieties unobtainable at groceries and vastly better.

It's very like having a pet animal. You could, I suppose, try to catch a fox or a possum or any other common animal of the neighborhood and try to make a pet of it. But the bother and expense are such that you do better to get a good dog to begin with or even, if you're not up to a dog, a cat.