Roots and tubers are energy stores of plants. Names and definitions can vary around the world
Potatoes are tubers, which are the tips of underground stems that swell with starch (a polysaccharide) and water. Potatoes are often classed as vegetables (in the USA, for instance).
Sweet Potatoes, sometimes called ‘yams’ in North America, are a type of storage root rather than a tuber, but
true Yams are starchy tubers.
Nagaimo are from the edible species: Dioscorea opposita or Dioscorea batatas. India: Garuda. Assam: Kosu. Also: Chinese Yam, Korean Mountain Yam, Japanese Mountain Yam.
Cassava (manioc) and Yucca are elongated roots, and Sago is a starchy food made from the pith of some types of Palm tree.
Taro is cultivated for its edible leaves, as well as its starchy corm, which is similar to a tuber.
Plantains are one of several fruits used as vegetables: they grow on trees and look like bananas, but only a small proportion of the starch is converted to sugar during the ripening process, which makes them similar to potatoes to cook with.
Chufa (tigernuts) are tubers that are 'ranked amongst the oldest cultivated plants in Ancient Egypt'. It is a small tuber of a species of Sedge native to areas of the northern hemisphere. Commonly made into a drink in Spain called horchata de chufas.
Composition
Roots and tubers are less concentrated stores of starch, although this accounts for almost all of their raw weight apart from water. Starch content varies from around 15–20 per cent in sweet potatoes to 25–30 per cent in cassava and yams, which translates into around 80–95 per cent of the dietary energy of these roots and tubers. Cooking sweet potatoes makes them taste sweet because an enzyme converts as much as 75 per cent of the starch into maltose (a disaccharide). Roots and tubers eaten with the skin on are high in dietary fibre. These foods are generally poor sources of protein, so although protein deficiency is uncommon, populations that subsist on these foods, and do not eat protein-rich pulses (legumes), are at risk of deficiency, especially children weaned on thin gruels made with these low-protein foods. They contain variable amounts of other nutrients. Potatoes contain vitamin C, for example, and the orange varieties of sweet potatoes contain carotenoids. Yams contain many bioactive compounds and taro corms are high in vitamin B6, fibre, and manganese.
Recipes:
Japanese/Korean Mountain Yam
Taro