Legume is a DEHISCENT DRY FRUIT (fruits that have dry pericarp) produced from a monocarpellary, superior ovary. Legume dehisces from both the sutures into two valves (opens along a seam). Because of the exceptional hardness of the seed coat some legumes are like stones.
Examples include beans, peas and peanuts, lentils, garbanzo beans, carob, mesquite etc.
Reference:
http://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Peanut_9417.jpg/200px-Peanut_9417.jpg
