Yautía/tannia

Sowing: Tannia is propagated vegetatively, typically from sprouted corm sections or the offshoot cormels that form around the main corm, rather than from seed. Plants raised this way can reach maturity within 14-20 weeks, and a single corm can give rise to ten or more new corms within about ten months.

Watering: The crop favours consistently moist, free-draining soil and needs regular watering to sustain its large leaf canopy, which can reach up to nine feet in height in the ground. In containers it requires a pot around 30-40cm across once mature, filled with a sharply draining mix of compost with added perlite, grit, or bark, and should never be left standing in water.

Pests and diseases: The most serious disease is root rot, caused primarily by the oomycete Pythium myriotylum, which produces stunted growth, wilting, chlorotic and withered leaves, and a poor root system, sometimes leading to complete crop failure. The pathogen persists in soil and spreads through infected planting material, often forcing growers to avoid replanting tannia in an infected field for at least five years; the main safeguards are disease-free planting stock, good drainage, crop rotation, and planting on ridges, with fungicides used once infection occurs.

Dasheen mosaic virus is the other major problem, causing chlorotic mosaic patterning along the leaf veins and stunting without killing the plant outright. It spreads through infected planting material and by aphids feeding on sap, so using virus-free stock and keeping tools clean during propagation are the main precautions.

Corms are ready for digging within about ten months of planting, by which point a single plant may have produced ten or more of them; they should be lifted fully out of the soil rather than left behind. The leaves contain oxalic acid, which can irritate skin, so care should be taken when handling foliage at harvest.

Culinary: The corm is a starch-rich staple across the tropics, providing carbohydrates for human diets and cash income for farmers; the corms, cormels, and leaves together are counted among the world's most important root and tuber crops, feeding hundreds of millions of people.

Fodder: Beyond the kitchen, the corm and leaves also serve as animal feed.

Ornamental: The plant's large, arrow-shaped leaves have also made it a widely grown ornamental subject in tropical and subtropical gardens, the trait that gives it the common name elephant ear.

Tannia's precise native range is uncertain, but it is thought to originate in northern South America, including present-day Colombia, Peru, Ecuador, and Venezuela, where it was first brought into cultivation. From this base in tropical America the crop later spread to Southeast Asia and Africa, becoming established there by around the 19th century.