The yacón (Smallanthus sonchifolius) is a species of perennial daisy traditionally grown in the northern and central Andes from Colombia to northern Argentina for its crisp, sweet-tasting, tuberous roots. Their texture and flavour are very similar to jicama, mainly differing in that yacón has some slightly sweet, resinous, and floral (similar to violet) undertones to its flavour, probably due to the presence of inulin, which produces the sweet taste of the roots of elecampane, as well. Another name for yacón is Peruvian ground apple, possibly from the French name of potato, pomme de terre (ground apple). The tuber is composed mostly of water and fructooligosaccharide.
Commonly called jicama in Ecuador, yacón is sometimes confused with that unrelated plant, which is a bean. The yacón, in contrast, is a close relative of the sunflower and Jerusalem artichoke. The plant produces a perennial rhizome to which are attached the edible, succulent storage roots, the principal economic product of the plant. The rhizome develops just under the surface of the soil and continuously produces aerial shoots. Dry and/or cold seasons cause the aerial shoots to die back, but the plant resprouts from the rhizome under favourable conditions of temperature and moisture. The edible storage tubers are large and typically weigh from a few hundred grams to a kilogram or so.
The tubers contain fructooligosaccharide, an indigestible polysaccharide made up of fructose. Fructooligosaccharides taste sweet, but pass through the human digestive tract unmetabolised, hence have very little caloric value. Moreover, fructooligosaccharides have a prebiotic effect, meaning they are used by beneficial bacteria that enhance colon health and aid digestion. And the leaves of the yacón contain quantities of protocatechuic, chlorogenic, caffeic, and ferulic acids, which gives tisanes made from the leaves prebiotic and antioxidant properties.
Yacón plants can grow to over 2 m in height and produce small, inconspicuous yellow flowers at the end of the growing season. Unlike many other root vegetables domesticated by the indigenous peoples of the Andes (ulluco, oca, and mashua), yacón is not photoperiod sensitive, and can produce a commercial yield in the subtropics, as well.
Traditionally, yacón roots are grown by farmers at midelevations on the eastern slopes of the Andes descending toward the Amazon. It is grown occasionally along field borders where the juicy tubers provide a welcome source of refreshment during field work. Until as recently as the early 2000s, yacón was hardly known outside of its limited native range, and was not available from urban markets; however, press reports of its use in Japan for its purported antihyperglycemic properties made the crop more widely known in Lima and other Peruvian cities. Companies have also developed novel products such as yacón syrup and yacón tea. Both products are popular among diabetics and dieters.