Watercress is in the same family as mustard and cabbage,with a somewhat bitter, peppery taste. The vegetable is full of vitamins, minerals and antioxidants. A serving has more iron than spinach and provides 312 percent of your daily vitamin K requirements, according to Food Facts.

Lettuce is much more than a primary salad ingredient or an accessory placed on your sandwich or burger. Cooking lettuce gives it an entirely new texture that can be used in soups, stews or for many easy Asian side dishes.

What is commonly known as rust on lettuce is technically known as “russet spotting.” Rust on lettuce doesn’t make the greens inedible, but it does make them unattractive.

Collard greens are a healthy food chock full of vitamins, minerals and fiber. They help lower cholesterol and detoxify the liver, according to Dr. Kevin Weiland in his book, "The Dakota Diet: Health Secrets from the Great Plains."

Collard greens contain calcium, potassium and vitamins A, C and K. One cup of collards contains more than 20 percent of your recommended daily value of fiber, and 5.7 g of protein. These thick, green leaves are related to cabbage, but unlike cabbage, collard greens grow loose instead of forming heads.

While iceberg lettuce has a bad reputation of being low in nutrients, that's not exactly true -- it's just lower in nutrients than some other types of lettuce. Iceberg lettuce serves as a good source of some essential nutrients, and at just 20 calories per serving, it fits into a calorie-conscious diet.

While dandelions are likely less than welcome on your lawn during the warmer months, they should be more than welcome on your plate. Their leafy greens offer a bitter, peppery flavor that works well raw or cooked.

The greens in a green salad can include iceberg, romaine, spinach, arugula, red leaf and any other green lettuce. Vegetables such as tomato, carrot and cucumber may also be tossed in. Calories will vary based on ingredients, serving size and the dressing you choose.

Lettuce wraps are a popular appetizer or small entree at many Asian-style restaurants. They typically feature a chopped chicken dish that you can spoon into a piece of lettuce, which functions as a wrapper. While lettuce wraps seem like a good nutritional choice, they should not be considered a low-calorie food.

One 3.5-oz. green apple with skin contains 52 calories. A 3.5-oz. apple has 48 calories if you eat it without the skin, according to the U.S. Department of Agriculture.

Iceberg lettuce can be a crisp, refreshing addition to salads or sandwiches, though its nutritional content pales next to its dark-green relatives. Darker lettuces like romaine and red leaf are richer in vitamin A, beta-carotene and other nutrients than iceberg.