Purslane - 马齿苋

Although the FDA classifies purslane as a broad-leaved weed, it's a popular vegetable and herb in many other countries, including China, Mexico, and Greece.

Why it's healthy: Purslane has the highest amount of heart-healthy omega-3 fats of any edible plant, according to researchers at the University of Texas at San Antonio. The scientists also report that this herb has 10 to 20 times more melatonin—an antioxidant that may inhibit cancer growth—than any other fruit or vegetable tested. (Video: Another omega-3-packed food you aren’t eating)

How to eat it: In a salad. Think of purslane as a great alternative or addition to lettuce: The leaves and stems are crisp, chewy, and succulent, and they have a mild lemony taste. Look for it at your local farmer's market, or Chinese or Mexican market. It's also available at some Whole Foods stores, as an individual leafy green or in premade salad mixes.