Common name: Cocoyam

Cocoyam is a fast-growing, perennial herb native to tropical America, with a natural range extending from the Caribbean to northern South America, where it has long been cultivated for its potato-like cormels, which are cooked and eaten as a starchy vegetable.

The leaves are eye-catching: dark green and heart-shaped, some up to 1 m (3 ft) long and nearly as wide. They sit atop pale green succulent stems that grow up from a central tuber that develops underground.

The stems, which may be 1 to 2 m (3 to 6 ft) tall, are thick at the base then taper toward the leaf end. They lean away from the centre of the plant, bent outward by the weight of the leaves. Because of their large size, the leaves touch or overlap, forming a dense, umbrella-like canopy.

The flowers are borne on an erect, finger-like spike partly enclosed by a large, semi-circular, cream-coloured bract or spathe, and sit on a short flower stalk at the centre of the plant, just beneath the leaves.

Flowers are either female or male, borne separately on different parts of the spike, with the female flowers closer to the base. Even when pollinated, they rarely produce seed.

Edible cormels are around the size of a large potato. Elongated at one end, they develop attached to the outside of the central tuber. They have thick, rough brown skin with white flesh underneath, though it can be yellow or pink depending on the variety.

Cormels (Balaclava, Jamaica)

Edible uses

Cooked vegetable - When peeled, cormels can be prepared like potatoes: roasted, boiled, or steamed on their own; cooked in soups or stews; or mashed or pureed. The flavour is starchy like a potato, earthy and slightly nutty. The small young leaves are also edible and can be cooked and served as a leafy vegetable, similar to spinach.

Chip or crisp - The peeled cormels can also be sliced and fried to make chips, crisps, or fritters.

Flour - They can also be ground and dried to make flour.

Natural thickening agent - Or grated to make a starch used as a thickening agent. Only the cormels are eaten, not the central tuber, which is unfit for human consumption.

Material uses

Livestock feed - Farmers sometimes cut the leftover central tuber into pieces, boil it, and feed it to pigs.

Livestock forage - Cattle, sheep and goats forage the leaves, which have a reported crude protein content of 22% of their dry weight.

Environmental uses

Foliage ornamental - The plant is occasionally cultivated as an ornamental for its massive leaves, which add a lush tropical look to gardens.

Climate

It grows naturally and is productive in humid subtropical and tropical lowland climates, generally areas with annual lows of 13 to 25°C, annual highs of 24 to 35°C, annual rainfall of 1200 to 6000 mm and a dry season of 4 months or less.

Growing

New plants are grown either from surplus cormels, sections of the central tuber, or stems with a piece of central tuber intact. Overall, growth rates and cormel yields are best when you use sections of the central tuber for planting.

It performs best in free-draining, rich loam soils with a slightly acidic to neutral pH (generally 5.5 to 7.0) and in full sun to light shade. Though it thrives in moist soils along stream banks, it does not tolerate waterlogging.

The cormels can be harvested after about five months and as needed until the plant starts to die back, usually around nine to ten months, indicated by the older leaves turning yellow. Care is taken when unearthing the cormels not to cut or bruise them, as this will shorten their shelf life, which is usually around three months when stored in a cool, dry place.

Average yields of 1 to 2 kg (2 to 4 lbs) per plant can be expected, or between 10,000 and 20,000 kg per hectare (4.5 to 9 tons per acre) per year in intensive farming systems, with yields as high as 30,000 kg per hectare (13 tons per acre) having been reported.

Problem features

Although it rarely sets seed, tuber or cormel pieces left in the ground will grow to form new clumps of plants. It is recorded as having escaped cultivation and as an agricultural weed, mainly in countries in the Pacific region.

All plant parts, especially the central tuber, contain calcium oxalate, a gastrointestinal irritant if consumed raw or uncooked, mainly causing burning and inflammation of the mouth and throat. The plant sap may also irritate skin and eyes in some people.

Books

• Adams, C. D. 1972, Flowering plants of Jamaica, University of the West Indies, Mona, Greater Kingston

• Elevitch, C. R. & Thaman, R. R. 2011, Specialty crops for Pacific islands, 1st ed, Permanent Agriculture Resources, Hawaii

• Gohl, B. 1981, Tropical Feeds : feed information summaries and nutritive values (Revised edition), Food and Agriculture Organization of the United Nations (FAO), Rome

• Hanson, B. 2007, Buried treasures : tasty tubers of the world : how to grown and enjoy root vegetables, tubers, rhizomes, and corms, Brooklyn Botanic Garden, Brooklyn, New York

• Higman, B. W 2008, Jamaican food : history, biology, culture, University of the West Indies Press, Kingston, Jamaica

• Horton, D. 1988. Underground crops: long-term trends in production of roots and tubers. Winrock International, USA.

• Leon, J & Hernandez Bermejo, J. Esteban & Programma Ethnobotanica 92. 1994, Neglected crops : 1492 from a different perspective, Food and Agriculture Organization of the United Nations, Rome

• Litzenberger, S. C. 1974, Guide for field crops in the tropics and the subtropics, Office of Agriculture, Technical Assistance Bureau, Agency for International Development (USAID), Washington D.C.

• Morgan, D. & Achilleos, A. 2012, Roots : the definitive compendium with more than 225 recipes, Chronicle Books, San Francisco

• National Research Council (Board on Science and Technology for International Development) 1975, Underexploited tropical plants with promising economic value, National Academic Press, Washington D. C.

• Nelson, L. & Shih, R. & Balick, M. J., 2007, Handbook of poisonous and injurious plants, 2nd ed, New York Botanical Gardens, Springer, New York

• Perkins, K. D. & Payne, W. 1981, Guide to the poisonous and irritant plants of Florida, Florida Cooperative Extension Service, Gainesville, Florida

• Purseglove, J. W. 1981, Tropical crops: Monocotyledons, Longman, Harlow, London

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

• Randall, R. P. 2007, The introduced flora of Australia and its weed status, Cooperative Research Centre for Australian Weed Management, Glen Osmond, South Australia

• Roecklein, J. C & Leung, P.S. 1987, A Profile of economic plants, Transaction Books, New Brunswick, New Jersey