In South Florida, farmers are replacing citrus groves with crops such as carambola (star fruit) and mamey, the so-called "Cuban national fruit." The latter is so popular, according to Chris Rollins, director of the 20-acre, 500-specie Fruit and Spice Park in Homestead, that the available supply never leaves the state.

In Los Angeles, Frieda Caplan, whose specialty produce firm (Frieda's Finest) sells to every major food retailer in the country, said this year's news is of no single fruit or vegetable, but that "everything fresh is hot."

And in Washington, Joe Reintzel, manager of Kossow Gourmet Produce, a wholesale firm, said "we have no problem finding a home for the new and different."

The "new and different" in this case are those fruits and vegetables poised to refashion the composition of produce departments throughout the country -- the new generation of edible exotica. Current attractions include fruits such as red bananas, pepino melons, cactus pears, tomatillos and cherimoyas (also known as custard apples), and vegetables such as radish sprouts, baby acorn squash and cactus pads (nopales).

Though a number of these "foreign" elements arrive from Mexico, the Carribbean or still farther, some, such as the carambola, have been in our own back yard (in this case, Florida) for decades, but were never raised commercially. And these recent introductions are now being displayed alongside items that were themselves new arrivals just a few years ago: jicama, bok choy, plantains and the like.

It's no less than a revolution in the produce section, and it's a revolution taking place not only on both coasts, but across the country as well. "Every major retailer has expanded the size of its produce section," proclaimed Caplan, who is credited with introducing the kiwifruit to the American public in the early '60s. "Retailers have learned that the produce department is the most profitable part of the store, and the main reason why consumers choose a store is because of its produce section" and the variety therein.

Gary Gionnette, produce merchandising manager for Washington's Safeway stores, concurred, and referred to perhaps the most revealing evidence: In 1974, the number of items stocked in a given grocery's produce section was estimated at 65 items. Ten years later, that figure had more than tripled, to include 216 stocked items. Additionally, the United Fresh Fruit and Vegetable Association's Supply Guide of available produce, issued within the food trades, was recently updated to include nearly 75 new fruits and vegetables.

(Home gardeners are demanding more variety, too. In its 1986 seed catalogue, the W. Atlee Burpee Company has included a new section on oriental seeds, such as pak choi, Chinese cabbage, celtuce and others.)

"Whatever you have, people will try," noted Caplan. "You can find the same things in Ames, Iowa as you can in Albuquerque, New Mexico."

The influx of ethnic populations -- Hispanics and Asians in particular -- is an obvious contribution to burgeoning displays of the varied produce in food markets. No longer must tomatillos and litchis be purchased in a canned state; area chain stores have in fact carved out entire sections for the display of such ethnic offerings.

"Anything oriental" sells well, offered Reintzel. Also contributing to the proliferation of such exotica are health concerns and the "fitness craze" of the American public, said Gionnette, pointing to the brisk sales of fresh herbs, "odd lettuces" such as raddichio (formerly found only abroad, but now being grown in California) and miniature vegetables. And Sutton Place Gourmet, which carries an estimated 300 items in its produce section, recently added gold chanterelles, pieds de mouton and pleurotes from France to the 16-20 types of mushrooms it already offers.

Not only are these new fruits and vegetables seen as a break from the tedium of the culinary ordinary, they've developed status among chefs and restaurateurs anxious to stay on the cutting edge.

"They use exotic produce to place themselves in a category above the others," acknowledged Reintzel.

The single biggest problem for the store handling such produce is that of the uneducated consumer, noted several area retailers. In some cases, the wholesaler is the only contact with the consumer in terms of information, providing tips in the form of recipes on the packaging. To counteract this, all 136 Giant stores carry a bound copy of "Very Special Produce," a comprehensive guide with instruction on the use and handling of everything from arugala to yucca root. Additionally, various fruits and vegetables are promoted on a rotating basis via recipe cards located in each store's produce section.

Another problem is that of the mislabeling -- intentional or not -- of produce unfamiliar to consumers. Said Reintzel, "Growers and distributors nickname produce," which makes it difficult for the consumer to determine whether it is a rare product, worth an exotic price, and to find information on how to use it. Opuntia occidentalis, for example, is known as cactus pear, prickly pear, tuna fruit, Indian pear, Indian fig and Barbary fig.

There's big money to be made in the new produce. The mamey, which tastes like "creamy sweet potato pudding," noted the Fruit and Spice Park's Rollins, "sells for $8-$9 a fruit, never less than $4." And the carambola is in such demand that growers are able to sell even the less desireable sour varieties. Though the tart carambolas are good for cooking, Rollins explained, the sweet ones are those the consumer should be looking for.

Certainly less of an obstacle now than ever before is the handling of exotic fruits and vegetables. "There were enormous risks with shipping just five years ago," noted Gionnette, who added that foreign importers have vastly improved their methods of inspecting, packing and shipping highly perishable produce.

Especially promising is last year's debut of 550 microprocessor-controlled high cube refrigerated containers -- unofficially known as "smart reefers" (refrigerated containers) -- on 17 vessels of the American President Lines, which operates the largest fleet of refrigerated containers (nearly 4,000) in the Pacific and Indian oceans. So that potential shipping problems can be recognized and rapidly resolved, the new technology was designed to continuously monitor the temperature of both container and produce from point of origin to destination. Moreover, the system is capable of "cold treating" the produce to destroy insects, thus avoiding the dangers of chemical treatment.

The next step? The monitoring of produce en route via satellite, hopes APL.

Herewith, an introductory primer on a few of the latest exotica to appear in the produce section:

*Carambola

What it is: Also known as star fruit, this waxy, yellow-gold juicy fruit ranges from 2 to 5 inches. Its name derives from its five deeply indented ribs; when cut this fruit looks like a star, making it an attractive garnish. Its season is September-February.

How to store: Refrigerate immediately and use within 3-4 days of purchase.

How to use: Taste ranges from sweet to sour. Sweet varieties can be eaten out of hand, in salads, cold dishes or beverages. (They lose their flavor somewhat in cooking.) Sour varieties lend themselves well to jellies, chutneys or as garnishes. To eat raw, look for yellow fruit to indicate ripeness. Green star fruit are best used for cooking.

*BANANA-STAR FRUIT PIE (Makes one 9-inch pie)

3/4 cup sugar

1/4 cup cornstarch

1/2 teaspoon salt

1 ( 1/4-ounce) envelope unflavored gelatin

3 cups milk

4 egg yolks

2 tablespoons butter

1 tablespoon vanilla

1 cup whipping cream

3 bananas, peeled and sliced

9-inch baked pie crust

1 medium lime

2 carambolas

In a 2-quart saucepan, combine sugar, cornstarch, salt, and gelatin with wire whisk. Beat in milk and egg yolks. Cook mixture over low heat, stirring constantly, until thickened, about 15 minutes. Stir in butter and vanilla. Cover surface of custard with plastic wrap and chill.

Whip cream and fold it, along with bananas, into custard. Spoon into pie crust and chill until set. Grate peel of lime and slice carambolas. Place carambolas on top of pie and sprinkle edge with lime peel.

*Cactus Pear

What it is: Also known as prickly pears, tuna fruit, sabras and Indian fig, cactus pears are slightly egg-shaped fruits ranging in color from yellow to magenta. Their taste and texture are similar to that of watermelon. Best supply available September through December, but also from March through May.

How to store: Allow to ripen at room temperature; refrigerate up to 3 days.

How to use: Cut the ends of the fruit and slit the skin down the center, lengthwise. Remove pulp with a spoon. Alternately, peel the cactus pear, slice it and sprinkle with lemon juice or cream and sugar. Use in sorbets, marmalades and in desserts.

*CACTUS PEAR BREAKFAST SHAKE (2 servings)

2 cactus pears, peeled and chunked

1 large banana, peeled and chunked

4 ice cubes

1 1/2 to 2 tablespoons honey

1 cup milk

Press cactus pears through the medium disk of a food mill. Combine pure'e in blender or processor container with banana, ice cubes, honey and milk; whirl until no chunks of ice remain. Serve at once. From "Uncommon Fruits & Vegetables; A Commonsense Guide" copyright by Elizabeth Schneider (Harper & Row, June 1986)

*Cherimoya

What it is: A heart-shaped green subtropical fruit, and a native of the mountains of Ecuador and Peru, this fruit bears distinctive thumb-print-like indentations on its surface. It tastes something akin to a fruity custard when ripe. Its season is November or December through May, weather permitting.

How to store: Allow to ripen at room temperature if hard. Since ripe fruit doesn't keep well (overripe fruit is usually cracked at the stem and turns brown), it's best to store in a refrigerator and use as soon as possible.

How to use: Best eaten out of hand, but can be halved or quartered and eaten with a spoon, or diced for use in fruit salads and desserts. The pure'ed fruit is used to make pies and sherbets. Good source of niacin, phosphorous and thiamine.

*CHERIMOYA-ORANGE PARFAIT (4 to 6 servings)

This recipe requires three cherimoyas.

1 cup whipping cream

1 cup sour cream

1/4 cup sugar

1/2 teaspoon vanilla

2 tablespoons orange juice

2 teaspoons lemon juice

Dash salt

1/2 cup pureed cherimoya

2 teaspoons grated orange peel

2 cups cherimoya chunks

1 1/2 cups orange sections

Mint leaves

Combine whipping cream and sour cream in a deep bowl, refrigerate with beaters until well chilled. Beat creams until frothy; gradually add sugar, vanilla, fruit juices and salt. Beat until quite stiff. Blend in cherimoya pure'e and 1 teaspoon orange peel.

Put half the cherimoya chunks in the bottom of 4 to 6 parfait glasses. Spoon in a layer of cream, all the orange sections, a second layer of cream and the remaining cherimoya. Top with a dollop of cream and garnish with remaining orange peel and mint leaves.

*Tomatillo

What it is: Also known as the Mexican green tomato, this relative of the husk tomato and ground cherry is usually found canned in Latin American food shops. In its fresh state, it appears in a papery husk. It resembles an apple in taste. Year-round availability.

How to store: Can be kept, in their husks, in a paper bag (don't use plastic) in the crisper of the refrigerator up to 3 weeks, sometimes longer.

How to use: Green in color, but turns yellow when ripe. Usually used when green, and cooked, for use in Mexican sauces, in combination with chilies and spices. To prepare fresh tomatillos, as in the recipe below, remove the husks and stems and wash well. Rarely eaten raw, the tomatillo's taste is enhanced by cooking. Can be steamed and added to salsas or Mexican dishes, in guacamole, or as a vegetable with cream cheese.

*DICED GAZPACHO SALAD (4 servings)

7 medium tomatillos (about 7 ounces), husks removed, rinsed

1/4 teaspoon salt

1/2 teaspoon oregano

1/4 cup (one handful) parsley, not chopped

Black pepper to taste

1/3 cup full-flavored olive oil

1 tiny red onion, diced ( 1/2 cup)

1 medium cucumber, seeded and cut into 1/4-inch dice (1 cup)

1 large red bell pepper, cut into 1/2-inch squares (1 1/2 cups)

1 small avocado, cut into 1/2-inch dice

Coarsely slice 2 tomatillos and combine in food processor with salt, oregano, parsley, and pepper; chop fine. Add oil and blend. Cut remaining tomatillos into 1/4-inch dice.

Combine diced tomatillos, onion, cucumber, and red pepper in a serving dish; toss with dressing. Add avocado and toss gently. Cover and chill for about an hour before serving.

From "Uncommon Fruits & Vegetables; A Commonsense Guide" copyright by Elizabeth Schneider (Harper & Row, June 1986)