What could be more American than watermelon on a hot afternoon?

We love our watermelons, sweet and juicy on a steamy summer day, especially in Texas. And we should: Texas is consistently in the top three watermelon-producing states, along with Florida and California.

Texas is also the cradle of the seedless watermelon, the wunderkind of the watermelon world. In the course of just two decades, seedless watermelons, developed north of Abilene, have taken over the market — accounting for a whopping 80 percent of retail watermelon sales in the United States today.

Another major change in the watermelon market over the last several years has been in its size, with the development of refrigerator-size melons and even watermelons for one, a boon to singles and small families who can’t possibly finish those big ol’ guys, much less find room for them in the fridge. For the most efficient refrigerator storage, the Japanese have even come up with cube-shaped watermelons, grown by enclosing the fruit in clear plastic boxes, though those aren’t likely to show up at our local grocers anytime soon.

But the folks at the National Watermelon Promotion Board report that there’s still demand for the old-fashioned seeded watermelons, especially in the South, where old habits die hard and plenty of folks go to roadside stands and farmers markets looking for the taste of their youth — and for fodder for seed-spitting contests at festivals and fairs.

Whether you’ve wholeheartedly embraced the seedless revolution, or whether you’re a die-hard purist who thinks a watermelon isn’t a watermelon unless it has seeds, here’s our summer guide to buying, serving, eating and having fun with watermelon.

TYPES AND VARIETIES

In the supermarket …

Between 200 and 300 varieties of watermelon are grown in this country and Mexico, but the National Watermelon Promotion Board tells us these are the five types you’re most likely to find in the supermarket:

PICNIC WATERMELONS

Popular varieties include:

Jubilee (oblong, 20-45 pounds, large brown seeds)

Crimson Sweet (round to oblong, 16-35 pounds; medium-size brown seeds)

Allsweet, (oblong, 18-30 pounds, small brown or black seeds)

Seedless watermelons

Triploid hybrid (round to oblong, 10-20 pounds; seeds are sparse, very small and insubstantial)

Refrigerator-size watermelons

Icebox (round, 5-15 pounds, dark seeds)

Yellow-fleshed watermelons

Seeded (round, 10-30 pounds, black seeds)

Seedless (round, 10-30 pounds)

Mini or personal watermelons

Red-fleshed (round, 1-7 pounds, usually seedless)

Yellow-fleshed (round, 1-7 pounds, usually seedless)

Wayne Murphy, co-owner of Fort Worth, Texas’ Ridgmar Farmers Market, says the Allsweet and the Crimson Sweet are two varieties that are particularly sweet. He also likes the orange-fleshed Orange Glow, though “it’s not real consistent. But if you get a good one, I don’t think there’s anything better.”

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A SLICE OF HISTORY

Africa’s Kalahari Desert is thought to be the place where watermelon originated. Egyptian hieroglyphics depict watermelons being harvested 5,000 years ago; the fruits often were entombed with royalty.

Merchant ships brought watermelons to countries along the Mediterranean Sea; by the 13th century, the Moors had spread watermelon through the rest of Europe.

Food historians believe watermelon was brought to the United States by African slaves.

—National Watermelon Promotion Board

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SEEDLESS VS. SEEDED

It all started when a scientist from Indiana, looking for a place with the ideal conditions to develop a marketable seedless watermelon, found his way to a farmer in Knox County, north of Abilene, Texas, with a bag of seed.

The scientist, O.J. Eigsti, and the farmer, Donald Johnson, teamed up, and the result was the golden crop of the watermelon industry. Today, Donald Johnson’s son, Dwayne, raises 15 million to 20 million pounds of seedless watermelons a year.

“There is no real difference between the taste of seeded and seedless,” says Leslie Coleman, director of communications for the National Watermelon Promotion Board in Orlando, Fla. Seedless watermelons are generally smaller than seeded, and their flesh is typically firmer, so they hold up better once cut. Murphy notes that “the seedless are consistently crisp, with firm flesh. The seeded, once they go past the peak of ripeness, the seed area starts getting soft. So you’ve got a wider window with the seedless.”

Seedless watermelons usually cost more per pound than their seeded counterparts because they’re harder to grow. The seeds that produce the hybrid melons must be sorted by hand, and seeded melons must be planted alongside the seedless vines to pollinate the blooms, since the hybrid seedless plants can’t fertilize themselves.

But watermelon-board marketing director Gordon Hunt says he’s seeing a bit of a nostalgic backlash for the increasingly harder-to-find seeded watermelons. “There’s still a demand for it, so the prices are going to go up” as farmers grow fewer of them.

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PICKING A GOOD ONE

When a watermelon is ripe, it loses its shine, and the skin on top — the portion of the melon that was exposed to the sun when it was in the field — becomes slightly rough to the touch, says Wayne Murphy of Ridgmar Farmers Market. A creamy belly — the portion of the watermelon that rested on the ground — is a good sign but not a guarantee of ripeness, Murphy says. Dwayne Johnson of Johnson Melon Corp. in Knox City looks for a slightly orange tinge on the pale belly.

Those with sensitive ears (and strong wrists) can “sound it out,” Murphy says: Hold the melon away from your body with one hand and slap it lightly with the other. A ripe melon should “ring,” he says, and you can feel it vibrate. A very high pitch indicates it’s probably green; “if it’s ‘dead,’ like when you slap your stomach, it’s probably overripe.” The exception, he says, is seedless watermelons, which have a higher pitch when ripe.

The National Watermelon Promotion Board advises you to lift watermelons before buying and choose one that’s heavy for its size.

If you’re at a farmers market, look for “sugar spots,” brown flecks on the surface of the skin, suggests “Los Angeles Times” food and wine columnist Russ Parsons in “How to Pick a Peach” (Houghton Mifflin, $27). (At supermarkets, Parsons says, these spots are usually seen as imperfections and are washed off before sale.)

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WHOLE OR PRE-CUT?

Should you buy a whole melon or pay for the convenience of pre-cut fruit without the rind? First, think about how soon you’re going to use the fruit: Generally, an uncut melon will hold its texture longer.

To figure out how much more you’re paying for the precut, use this guide from The Atlanta Journal-Constitution: Removing the rind will reduce about 40 percent to 50 percent of the weight. So, if you’re paying twice as much per pound for the precut than you’d pay for the whole melon, you’re really paying about the same money. Don’t expect that to be the case, though; precut is more likely to cost as much as four times more per pound.

Also, consider that you must refrigerate the precut melon, but the uncut melon can be stored at room temperature. The amount of beneficial antioxidants in watermelon rises when the melon is not refrigerated but stays the same when stored at lower temperatures, recent research has shown. 

AND THEY’RE GOOD FOR YOU

Watermelon is the produce champion when it comes to lycopene, the antioxidant that research suggests may help protect against cancer, heart disease and stroke. Research by the U.S. Department of Agriculture suggests that watermelon contains 40 percent more lycopene by weight than tomatoes. A 1-cup serving of watermelon contains about 9 milligrams of lycopene; a medium tomato contains 4 milligrams.

But recent research has found that storing watermelon in the fridge may not be the best way to maximize its antioxidant power. In watermelons stored at room temperature, the levels of lycopene rise, according to a 2006 USDA Agricultural Research Service study.

Of course, cut melon should always be refrigerated to keep it safe. And chilling your melon just for a couple of hours before serving is fine, the researchers said.

Watermelons are also a good source of vitamins A, B6 and C. They are 92 percent water, so they aid hydration.

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CLEVER WAYS WITH WATERMELON

Try these two fun serving ideas from the National Watermelon Promotion Board:

Watermelon pie a la mode

For each serving, slice a ½-inch thick pie-shaped wedge from a poundcake and place on a dessert plate. Cut the same number of 3-inch-thick watermelon wedges the same size as the cake slices and set the melon wedges carefully in a large colander to drain off excess liquid. Place each watermelon wedge atop a poundcake slice, top with a scoop of vanilla-flavored frozen yogurt and drizzle with strawberry syrup.

Watermelon snow cones

Use an ice cream scoop to make balls of watermelon; place melon balls on a wax-paper-lined cookie sheet and freeze for about 1 hour. Remove spheres from freezer and roll in vanilla yogurt, then in sweetened coconut; place each in an ice-cream cone or snowcone cup and top with sprinkles or jimmies.

Watermelon recipes

It’s hard to improve on a simple chilled wedge of ripe watermelon at the end of a picnic, but if you want to be trendy, think of using it in savory dishes, like watermelon gazpacho, watermelon salsas, and salads with feta cheese or cherry tomatoes.

You can update a salad of melon balls with a squeeze of lime and a sprinkling of chopped fresh mint. If you’re more adventurous, sprinkle in some chile powder and a pinch of cayenne pepper. “Minimalist” chef Mark Bittman, in his new “Quick and Easy Recipes From The New York Times” (Broadway Books, $19.95), suggests serving watermelon wedges Thai-style, with lime wedges for squeezing and salt and finely ground red chiles for dipping.

Of course, seedless melon is perfect for drinks, because you don’t have to pick out the seeds before pureeing the flesh.

WATERMELON MANGO MARGARITA

Serves 2 to 3

2 cups chopped seedless watermelon

1 ripe mango

Juice from 2 fresh limes

1 tablespoon sugar

1 tablespoon triple sec

2 jiggers tequila

2 cups ice

Place all ingredients in a blender and puree until smooth.

Nutritional analysis per serving, based on 2: 271 calories, 1 gram fat, 40 grams carbohydrates, 2 grams protein, 0 milligrams cholesterol, 6 milligrams sodium, 3 grams dietary fiber, 5 percent of calories from fat.

—National Watermelon Promotion Board

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WATERMELON WITH PARMESAN AND MINT

“Handy to eat while standing or strolling, these watermelon wedges can be served with cocktails or as a chic and refreshing start to a summer meal”

Serves 12 as hors d’oeuvre

4-pound piece of watermelon

½ teaspoon black pepper

¼ teaspoon salt

½ ounce Parmigiano-Reggiano cheese, grated with a rasp (¾ cup)

1½ tablespoons chopped fresh mint

Cut watermelon lengthwise into narrow wedges about 1½ inches wide, then cut wedges crosswise into ¾-inch-thick slices (They will be tall and pointed.). Trim rind to enable slices to stand upright.

Just before serving, stir together pepper and salt and sprinkle mixture over slices. Stir together cheese and chopped mint and sprinkle slices again.

Nutritional analysis per serving: 112 calories, 6 grams fat, 6 grams carbohydrates, 8 grams protein, 15 milligrams cholesterol, 398 milligrams sodium, trace fiber, 48 percent of calories from fat.

—“The Best of Gourmet: Sixty-Five Years, Sixty-Five Favorite Recipes” (Random House, $40)

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LIME CUPS FILLED WITH WATERMELON GRANITA

“Refreshing watermelon granita — the Italian frozen dessert that has grainier crystals than sorbet — is served in lime cups to resemble tiny watermelons. Currants mimic the seeds”

Serves 12

12 limes

1 cup sugar

2 cups water

4 cups watermelon cubes

½ cup currants or raisins

 To make lime cups, cut limes in half lengthwise. Working over a bowl to catch the juice, use a sharp knife to cut around the pulp of each half, leaving peel intact. Scoop out pulp, using spoon to loosen pulp from peel, and reserve 2 tablespoons lime juice for granita; discard the pulp.

For granita, stir together sugar and water in small saucepan; heat to boiling. Cool slightly.

Place watermelon in container of food processor; pulse to puree watermelon. Place a colander over a bowl and pour the pureed watermelon into the colander to strain, forcing watermelon through with back of spoon, if needed.

Stir reserved lime juice and cooled sugar mixture into pureed watermelon and pour mixture into a 13x9x2-inch pan; freeze until firm. After about 4 hours, take pan from freezer and scrape the frozen watermelon mixture with a spoon to make granita. Stir in currants.. Mound granita in lime cups and serve, if desired, on a bed of crushed ice.

Nutritional analysis per serving: 119 calories, 1 gram fat, 31 grams carbohydrates, 1 gram protein, 0 milligrams cholesterol, 4 milligrams sodium, 2 grams dietary fiber, 4 percent of calories from fat.

—Gale Gand, pastry chef of Tru restaurant in Chicago, courtesy of National Watermelon Promotion Board