It's summer, it's hot, and it's salad season. Besides watermelon and corn, salad is the perfect summer food. They're light, crisp and refreshing-- especially when paired with a tart dressing. They're fast and don't heat up a hot kitchen. And they're versatile with as many salads as the imagination can invent.

At the core of most summer salads is lettuce. Lettuce, plain lettuce, was viewed for years as a tasteless part of a salad that existed to be covered up with a thick, sticky dressing. But what a metamorphosis lettuce has seen in the last 10-15 years. Interesting new lettuces, each with their own personality and previously only available to the restaurant chef, have started replacing the ubiquitous iceberg lettuce in supermarkets. The assortment of gourmet lettuces available to the consumer gets bigger all the time.

To help us navigate the sea of these chic lettuces, ChefTalk turned to an expert. For decades, chefs have been relying on the George J. Corneille and Sons company to supply them with the best specialty produce. The company was founded in 1925 and is the oldest continual business at Chicago's famed South Water Market (a distribution hub for produce). Today, Tom Corneille, the grandson of the founder, manages the shop and has the same passion for quality produce that the generations before him have had. ChefTalk asked him to give his professional insights on some of the different gourmet lettuces. Here's what he had to say:

Mesclun: Originating in the south of France and northern Italy, mesclun is a mix of different lettuces that grow together in one geographic location. Traditionally, the character of the mesclun depended on what lettuces ( and sometimes herbs) were indigenous to a particular region. Sometimes the mesclun was spicy, other times mild. In these countries, the mesclun is cut and consumed the same day. By contrast, in the U.S., we combine a wider variety of lettuces from different locations and customize our mesclun mixes. This can make some excellent mescluns with a wide range of flavors. The lettuce is often picked several days before being used.

Frisee: A great little lettuce that is part of the chicory family. It is lacy and pleasantly bitter. As the lettuce grows, each head is tied up so that the sun does not penetrate the center of the lettuce as it finishes growing. This process "blanches" the frisee since the plant needs the sun to develop its normal green leaves. The delicate white leaves are considered a delicacy and are the least bitter.

Radicchio: A native of Italy, there are 3 types of radicchio seen in the United States. The most common is the round head that looks somewhat like a small red cabbage. It has a fairly assertive bitterness. The red elongated radicchio, known as Trevisso radicchio, originates in the northern part of Italy near Trevisso and is a milder than its round cousin. The third variety of radicchio, the castel frano, is rarely seen in America. It has elongated leaves, is white with light purple veins, and is mild.

Arugala: Another Italian native, arugala is considered by some an herb since its flavor is assertive, not unlike horseradish. Tom counsels that it should be consumed when the growing weather is cool as this produces a mild arugala. When the weather warms up, the arugala becomes increasingly hot and peppery, and has more insect problems. Tom also recommends searching out a wild variety of arugala, the sylvetta, which has the flavor of roasted peanuts. Add small amounts of arugala to a salad for added zing!

Dandelion: Yes, that pesky weed also is a great salad green. It is commonly used throughout all of the Mediterranean. Beware of large leaves. These are not for salads, but rather for dishes involving long braising. Long cooking is necessary to remove the large leaves' bitterness and to tenderize them. By contrast, the tiny leaves are perfect for salad. They are refreshingly bitter and go well with a tart vinaigrette. Tom cautions that you should not harvest dandelions from lawns as often lawns are treated with dangerous chemicals.

Mache: This is one of Tom's favorite greens. It is also called "lamb's lettuce" because the sheep liked to graze on it in Europe, or "corn salad" because it grows well in the shade between rows of corn. It is a delicate and sophisticated lettuce with small, tender, green round leaves. It is grown 3 different ways-- in French greenhouses (which Tom thinks is "extra good"), hydroponically (Tom thinks they lose some flavor since it is grown in water), and outdoors which produces less delicate leaves.

Watercress: These dark green leaves have been known for centuries for their peppery bite that is great for salads, soups and sauces. Traditionally, it was found in the wild along the banks of brooks or streams-- thus the name. The watercress grown outdoors has a thicker stem and an assertive peppery bite. Conversely, watercress grown in hothouses are more tender and delicately flavored. Tom tells ChefTalk that his dad always told him that the best watercress came from Louisiana.

Belgium Endive: Known as Witloof in Belgium, this special lettuce is the king of the chicory family and has a very long history. It is shielded from the light as it grows, thus producing a solid, white, torpedo-shaped lettuce. It is mildly bitter and when cooked and served hot (typically braised or sautéed), it becomes somewhat sweet.

Baby Lettuces: Today, there is a large market for tiny miniature lettuces. Tom highlighted several of the many varieties:

Red and Green Oak Leaf: This French native likes cool weather. As a baby lettuce it has a short shelf life. In France, they pick it a bit larger than we do in America, and Tom thinks this is preferable since it gives the lettuce a better flavor and texture.

Lolo Rosso: Originally from Italy, this lettuce has a festive appearance with its frilly edges and deep red colors. As with oak leaf, in Italy it is harvested when larger than is found in the U.S. which produces a better flavor and more crunchy texture.

Baby Romaine: Known as Cos in Europe, Tom feels that the European varieties produce a softer and more tightly wound head of lettuce. The American varieties tend to be more fibrous and a bit tougher