Taro or colocasia is a popular tropical tuber crop grown for its edible root tubers and succulent, tender shoots and young leaves. Colocasia tubers are used as a staple food and as a vegetable in many countries. Colocasia leaves are used as a tropical leafy vegetable. There are many varieties of colocasia that are cultivated for edible purposes. Tubers of some varieties of colocasia may contain considerable amounts of an acrid compound called calcium oxalate which can be destroyed by proper cooking. Yams are a group of monocot plants, precisely speaking, a group of perennial herbaceous vines grown for their starch-rich, edible tubers. They belong to the family Dioscoreaceae and genus Dioscorea. Yams are widely grown in both temperate and tropical parts of the world and considered as an important food crop in the tropical areas of America, Asia and Africa. Yams are a rich source of carbohydrates. There are white yams, purple yams and yellow yams, depending on the colour of the tuber flesh.