Featuring a variety of crops, summer gardens throughout the valley are providing home chefs with fresh produce for warm weather meals.

All manner of squash and beans are prevalent and it won't be long before we'll be overrun with tomatoes and sweet, juicy ears of corn.

The time is right as well to feature nutritionally rich greens as part of summer meals. Greens are often overlooked in favor of more colorful garden crops.

Cooking greens are a tradition in the South, with many who live south of the Mason-Dixon line superstitiously thinking they bring good luck for the upcoming year when eaten on New Year's Day.

These flavorful, healthy greens include any type of cabbage where the green leaves do not form a compact head. Collard, mustard, kale, Swiss chard and broccoli rabe are all varieties of cooking greens. These humble vegetables are ancient -- meaning they haven't been tampered with over the centuries.

For years and years, these "headless" members of the cabbage family failed to gain wide culinary acceptance in the United States, with the exception of the Southeast. This has recently changed, with a broadening awareness of vegetable cookery in general, and as a result of nutritional concerns in particular.

During a recent visit to the Napa Farmers Market at Copia, we discovered a variety of cooking greens among the harvest offered by Mark Haberger's Big Ranch Farms. The Napa-based farmer grows several varieties of kale and chard. He and other vendors at area farmers markets should have cooking greens on display for a few more weeks. Let's examine what's here:

Collard Greens

Collards are the oldest known greens in the cabbage family, dating back to ancient times because of their similarity to cabbage eaten by prehistoric people. In addition, ancient Greeks and Romans cultivated collard greens.

Collards are native to the eastern Mediterranean region and Asia Minor. In approximately 400 B.C., they were brought to Britain and France by either the Romans or Celts. The first documentation of collard greens in America was in 1669, though it is possible they were present in the colonies at an even earlier date.

Collard greens grow best in warm weather though they can withstand the cold temperatures of late autumn. Interestingly enough, the flavor of collard greens is enhanced by a light frost.

Mustard Greens

Mustard greens are the most pungent of the cooking greens and lend a peppery flavor to food. They originated in the Himalayan region of India more than 5,000 years ago. Like many other cooking greens, mustard can be found in many Chinese, African-American and southern dishes. The mustard plant is characterized by its crumpled or flat leaves that may have scalloped, frilled or lacy edges. In addition, this plant produces the brown seeds that are used to make Dijon mustard.

Mustard greens are an excellent source of both vitamins A and C as well as fiber and protein.

Kale

Like other greens, kale descends from wild cabbage that originated in Asia Minor, and it is quite popular in Scandinavia, Germany, Holland and Scotland. Kale was brought to the United States in the 17th century by English settlers. It is now a favorite in the South where, like many cooking greens, it has been considered a poor man's food.

With long ruffled leaves resembling large parsley sprigs and hues that vary from lavender to chartreuse, kale has a mild cabbage-like taste and delicate texture.

Like most cooking greens, kale can grow in colder temperatures and withstand frost -- helping produce even sweeter leaves. Tuscan kale, also known as cavolo nero or lacinato kale and often marketed as dinosaur kale, is especially laborious to trim and clean, but worth seeking out for its distinctive nutty flavor.

Nutritionally speaking, kale is a superstar. It is an excellent source of vitamin A, folic acid, and vitamin C and contains both protein and fiber. Kale is loaded with calcium, potassium, indoles (cancer-fighting substances), beta-carotenes and other antioxidants.

Swiss Chard

The vegetable's scientific name is beta vulgaris, subspecies cicla, with the word cicla referring to Sicily where Swiss chard first grew. Its popular name stems from the fact a Swiss botanist determined the plant's scientific name. Today, Swiss chard is most popular in the Mediterranean, and has found favor as well in northern Europe and South America.

Swiss chard is extremely versatile, has a mild, sweet, yet slightly bitter flavor (similar to beets), and has large green leaves with ribs running throughout. The leaves can be smooth or curly and are attached to fleshy, crunchy white, red or yellow celery-like stalks.

Swiss chard is an excellent source of vitamins A and C, and also contains potassium and fiber.

Broccoli Rabe

Broccoli rabe was originally cultivated in the southern Mediterranean. It was brought to the United States in the 1920s by Italian farmers. Broccoli rabe has been most popular in the Italian and Asian communities.

Broccoli rabe looks similar to thin broccoli stalks with small clusters of buds and smooth leaves with sawtooth edges. Broccoli rabe has a somewhat bitter taste and should be cooked to help mellow that taste. It is an excellent source of vitamin C and also contains beta-carotene, fiber and phytochemicals.

The Register is including several recipes today for cooking greens, ranging from a simple saut to an old Czech recipe for very unusual kale patties. From Spain's Catalonia there's a recipe for chard with raisins and pine nuts,plus we offer a traditional recipe for Tuscan kale soup and a tasty frittata that incorporates chard.