yacon (yacón), a perennial plant grown in the Andes for its crisp, sweet-tasting tuberous root. The texture and flavour have been described as a cross between a fresh apple and watermelon which is why it is sometimes referred to as the apple of the earth. The root is composed mostly of water and fructo-oligosaccharides. It has recently been introduced into farmer's markets and natural food stores in the US. (source: Wikipedia)