Plant Profile – Cocoyam
Cocoyams are herbaceous perennial plants belonging to the family Araceae and are grown primarily for their edible roots, although all parts of the plant are edible. Cocoyams that are cultivated as food crops belong to either the genus Colocasia or the genus Xanthosoma and are generally comprised of a large spherical corm (swollen underground storage stem), from which a few large leaves emerge. The petioles of the leaves stand erect and can reach lengths in excess of 1 m (3.3
ft). The leaf blades are large and heart-shaped and can reach 50 cm (15.8 in) in length. The corm produces lateral buds which give rise to tubers or cormels and suckers or stolons. Cocoyams commonly reach in excess of 1 m (3.3 ft) in height and although they are perennials, they are often grown as annuals, harvested after one season. Colocasia species may also be referred to as taro, old cocoyam, arrowroot, eddoe, macabo or dasheen and originates from Southeast or Central Asia. Xanthosoma species may be referred to as tannia, yautia, new cocoyam or Chinese taro and originates from Central and South America.
Cocoyam is most commonly grown for its starchy edible roots. Colocasia is grown for its corm which is consumed after boiling, frying or roasting. The corms can be dried and used to make flour or sliced and fried to make chips. The leaves of the plant are also edible and are usually consumed as a vegetable after cooking in dishes such as stews. Xanthosoma species produce tubers much like potato and are boiled, baked, steamed or fried prior to consumption. The corm of some varieties is also consumed. Young leaves are eaten as a vegetable.
Cocoyam corms and leaves cannot be consumed raw; and must be cooked or processed before eating. This is because they contain high levels of oxalates which can cause itchy or irritating sensation in the throat when consumed raw. This is also the reason why cocoyam causes itchy skin in some individuals. Cooking and other processing methods like soaking in water for a long time destroys the oxalate.