Like the potato and eggplant, the tomato is a member of the nightshade family. It's the fruit of a vine native to South America. By the time European explorers arrived in the New World, the tomato had made its way up into Central America and Mexico. The Spanish carried plants back home from Mexico, but it took some time for tomatoes to be accepted in Spain because it was thought that — like various other members of the nightshade family — they were poisonous. Some tomato advocates, however, claimed the fruit had aphrodisiac powers and, in fact, the French called them pommes d'amour, "love apples. " It wasn't until the 1900s that the tomato gained some measure of popularity in the United States. Today this fruit is one of America's favorite "vegetables," a classification the government gave the tomato for trade purposes in 1893. Dozens of tomato varieties are available today — ranging widely in size, shape and color. Among the most commonly marketed is the beefsteak tomato, which is delicious both raw and cooked. It's large, bright red and slightly elliptical in shape. Globe tomatoes are medium-sized, firm and juicy. Like the beefsteak, they're good both raw and cooked. Another variety is the plum tomato (also called Italian plum), a flavorful egg-shaped tomato that comes in red and yellow versions. The medium-sized green tomato has a piquant flavor, which makes it excellent for frying, broiling and adding to relishes. The small cherry tomato is about 1 inch in diameter and can be red or yellow-gold in color. It's very popular — both for eating and as a garnish — because of its bright color and excellent flavor. The yellow cherry tomato is slightly less acidic than the red and therefore somewhat blander in flavor. Though it's long been popular raw in salads, the cherry tomato is gaining favor as a cooked side dish, quickly sautéed with herbs. The yellow pear tomato is slightly smaller than the cherry tomato and resembles a tiny pear. It's used in the same manner as the cherry tomato. Currant tomatoes are the tiniest of the species, measuring only about 0. 7 inches in diameter and weighing about 1/8 ounce. They come in both red and yellow varieties and have a sweet, crisp flesh. Finding a niche in some produce markets are several unique looking and flavorful heirloom tomato varieties. Among the more interesting are the purple tomatoes (such as Pruden's Purple, Brandywine and Cherokee Purple), the skins of which can range in color from a dusky pink with purple shoulders to a vivid dark pink. Depending on the variety, the flesh color can vary from crimson to a brownish purple-pink. Striped tomatoes (such as striped German) have an orangey skin with faint red striations. This fruit's bicolor flesh is a brilliant yellow with a red center. Fresh tomatoes are available year-round, with the peak season from June through September. The most succulent, flavorful tomatoes are those that are "vine-ripened," usually only available in specialty produce markets. Unfortunately, such tomatoes are very perishable, which is why supermarkets almost always carry tomatoes that have been picked green and ripened with ethylene gas or in special warming rooms. Such tomatoes will never have the texture, aroma and taste of the vine-ripened fruit. Choose firm, well-shaped tomatoes that are noticeably fragrant and richly colored (for their variety). They should be free from blemishes, heavy for their size and give slightly to palm pressure. Ripe tomatoes should be stored at room temperature and used within a few days. They should never be refrigerated — cold temperatures make the flesh pulpy and kills the flavor. Unripe fruit can be ripened by placing it in a pierced paper bag with an apple for several days at room temperature (65° to 75°F). Do not refrigerate or set in the sun. Tomato skins can be removed by blanching. Sun-dried tomatoes are, as the name indicates, dried in the sun (or by other, artificial methods). The result is a chewy, intensely flavored, sweet, dark red tomato. Sun-dried tomatoes are usually either packed in oil or dry-packed in cellophane. The dry-pack type benefits from soaking in oil or other liquid before use. Sun-dried tomatoes add their rich flavor to sauces, soups, sandwiches, salads and myriad other dishes. Canned tomatoes are available in various forms including peeled, whole, crushed, and those with herbs such as oregano and/or basil added. Tomato paste, which is available in cans and tubes, consists of tomatoes that have been cooked for several hours, strained and reduced to a deep red, richly flavored concentrate. Canned tomato puree consists of tomatoes that have been cooked briefly and strained, resulting in a thick liquid. Tomato sauce is a slightly thinner tomato puree, often with seasonings and other flavorings added so that it is ready to use in various dishes or as a base for other sauces. Tomatoes are rich in vitamin C and contain appreciable amounts of vitamins A and B, potassium, iron and phosphorus. A medium tomato has about as much fiber as a slice of whole-wheat bread and only about 35 calories. See also tomatillo.