Like so much in life that is desirable, sour cherries are hard to find, hard to keep and worth going after. These ruby-red sour delicacies -- also known as tart cherries and by the old-fashioned term pie cherries -- are delicate, juicy, luscious and mouth-puckering. But their season, especially around here, is all too brief -- the end of June and early July. What's more, they are fragile, so perishable, in fact, that they won't last but a day or so after being picked.

"Tart cherries have a natural bright red color, and after you harvest the cherry, that color is affected by heat and light," says Jane Baker DePriest, director of marketing at the Cherry Marketing Institute, in Lansing, Mich. "Even putting the cherries in a basket in the sunlight will cause their color to fade."

Sour cherries should not be confused with their sweet cousins, such as the deep-red Bing and the yellow and blush Rainier, which are bigger, firmer and great for eating out of hand but make mediocre baked desserts. Sour cherries are too tart for most people to enjoy raw, but they make superb preserves, pies and cobblers. They hold their shape better in cooking than sweet cherries do, even though they are softer and more delicate in their raw state. When cooked, their tartness mellows into a complex sweetness. They pair well with everything from vanilla ice cream to roast duck.

Until last summer I had not seen fresh sour cherries since I moved here from Michigan in 1995. That state grows 70 percent to 75 percent of the nation's commercial sour cherry crop, with Utah and Washington being the only other commercial producers. The climate and soil on the shores of Lake Michigan in the western part of the state make for ideal growing conditions, which is what Catholic and Protestant missionaries discovered when they planted the first trees along Traverse Bay in the 1800s. If you drive up the lake's edge in mid-summer, around Traverse City or out on Old Mission Peninsula, you will see acres and acres of trees dripping with luminous red fruit. But even in Michigan, the season for sour cherries is short -- a month total if you start in the southern part of the state and work your way up.

The yield of sour cherries is much smaller than that of sweet cherries, which are grown mostly in the Northwest. Last year, the United States produced 236,960 tons of sweet cherries on 75,890 acres, compared with 102,512 tons of tart cherries on 37,300 acres. The total value of U.S. sweet cherry production in 2003 was $327 million, while sour cherry production totaled $84 million. Sour cherries are also vulnerable to natural disasters; in 2002, a late-spring frost in Michigan wiped out nearly the entire crop.

There are two major kinds of sour cherries, amarelle and morello. The ones we see (when we see them) are known as Montmorency and are part of the amarelle classification. Their skin is bright red, but the flesh inside is pale yellow. Morello cherries, which are more prevalent in Europe, have darker skin and garnet red flesh.

Because sour cherries, especially the Montmorency variety, are so perishable, they rarely appear in grocery store produce aisles. Indeed, the vast majority of the crop ends up in cans or jars, in products such as pie filling or preserves.

"From my perception, they are one of the most delicate and refined and elegant fruits that you can ever find," says Justin Rashid, president of American Spoon Foods, a Michigan-based company that sells gourmet fruit products. "But because of the practical obstacles, the practical limitations to their fruit, their delicacy, their very brief season, tart cherries had been relegated to a pretty low status in the United States."

With its line of spoon fruits, preserves and dried cherries, American Spoon Foods has tried to elevate the status of sour cherries from starchy canned-pie filling ingredient to fancy snack and beyond. Dried tart cherries, an alternative to raisins, are available just about everywhere, and are used to brighten salads and slaws, and in snacks from trail mixes to chocolate-covered treats.

Tart cherry juice concentrate also has been gaining in popularity, says the Cherry Marketing Institute's DePriest, in part because recent research has shown it contains high concentrations of cancer-fighting antioxidants as well as anti-inflammatory properties.

Some cherry orchards and tart cherry-processing companies also sell a product known as IQF (individually quick frozen) cherries, which are as close to fresh as you can get. The pitted cherries are frozen at 100 degrees below zero. They can be substituted for fresh cherries in pies and other recipes. However, I conducted a spot-check of area supermarkets and grocery stores, and while several carried bags of frozen sweet cherries, none had the tart ones. The cherries can be ordered online and shipped overnight, but be prepared to pay: The price from one Michigan orchard for a five-pound bag (scarcely enough to make three pies) was $66.

Domenica Marchetti last wrote for Food about clams.