Collard greens (Brassica oleracea; Acephala Group) are a large-leafed, dark green relative of the cabbage. Collard greens are related to kale and mustard greens as well, and are relatively mild, the flavor approximating a combination of cabbage and kale. Unlike the curly-leaved kale, collard greens have smooth leaves.

Collard greens are native to the Mediterranean region. Ancient Greeks and pre-Christian Romans cultivated this vegetable. There is evidence that collard greens have been grown in Britain for over a thousand years. The first record of collard greens in the United States dates back to the 1600s.

Today, collard greens are widely cultivated in the American South, as well as Brazil, Spain, Portugal, regions of Africa, and other areas as well. The loose-leafed, nonheading plant is relatively hardy, tolerating frost and cold better than any of its cabbage cousins.

A 1 cup (190 g) portion of cooked collard greens has about 50 calories and is packed with nutrients. It is an excellent source of vitamins C, A, and K, as well as manganese and folate. In addition, this same serving will provide a good source of calcium, fiber, and beta-carotene, as well as vitamin E. Rich in nutrients and antioxidants, collard greens are beneficial for supporting the immune system, the skin and bones, the eyes, and for aiding digestion.

Collard greens are available year-round — fresh, frozen, and canned. When choosing fresh collard greens, avoid any leaves that are wilted or discolored and select only those that are deep green and unblemished. The smaller the leaf, the milder its flavor and the more tender it will be.

Collard greens keep better than other types of greens in the refrigerator, but they will grow bitter if they stand too long. Wrap unwashed leaves in damp paper towels and place in a resealable plastic bag in the crisper drawer of the refrigerator. Use within five days.

Because they have a tendency to be sandy, fresh collard greens should be washed thoroughly prior to cooking. An effective method of removing grit and sand is to trim the root ends from the stems and submerge the leaves in a bowl of water. Use your hands to swish the leaves through the water, allowing the dirt to fall to the bottom. Remove the leaves to a colander, rinse with clean water, and replace the water in the bowl. Repeat this process two or three times, until no dirt is visible at the bottom of the bowl.

Before cooking, trim off any tough stems or midribs. The traditional Southern method of cooking is to slowly simmer the collard greens in water with a bit of salt pork for flavor, until very tender. Alternatively, collards can be simmered in broth, omitting the pork. Because they are so fibrous, it can take about 45 minutes to 1 hour for collards to cook. Vinegar complements the bitterness of the collard greens and is often served alongside them as a condiment.

Brazilian cooks feature collard greens in soups and stews such as feijoada and caldo verde, and sauté them with oil, garlic, and salt as a side dish for meat and fish entrees.