Yam is the common name for some plant species in the genus Dioscorea (family Dioscoreaceae) that form edible tubers (some other species in the genus are toxic).

There are perennial herbaceous vines native to Africa, Asia, and the Americas and cultivated for the consumption of their starchy tubers in many temperate and tropical regions.

The tubers themselves, also called “yams”, come in a variety of forms owing to many cultivars and related species.

Description

A monocot related to lilies and grasses, yams are vigorous herbaceous, perennially growing vines from a tuber. About 870 species of yams are known, a few of which are widely cultivated for their edible tuber but others of which are toxic (such as D. communis).

Yam plants can grow up to 15 meters (49 feet) in length and 7.6 to 15.2 centimeters (3 to 6 inches) high. The tuber may grow into the soil up to 1.5 m (5 ft) deep. The plant disperses by seed.

The edible tuber has a rough skin that is hard to peel but readily softened by cooking. The skins change in color from dark brown to light pink.

The majority, or meat, of the vegetable, is composed of a much softer substance ranging in color from white or yellow to purple or pink in mature yams.

How Yam is Cultivated

Yams are planted for the consumption of their starchy tubers in many temperate and tropical regions, especially in West Africa, South America the Caribbean, Asia, and Oceania. About 95% of yam crops are grown in Africa.

A yam crop begins when whole seed tubers or tuber portions are planted into mounds or ridges, at the beginning of the rainy season. The crop yield depends on how and where the sets are cultivated, sizes of mounds, interplant spacing, provision of stakes for the resultant plants, yam species, and tuber sizes desired at harvest. Small-scale farmers in West and Central Africa often intercrop yams with cereals and vegetables.

The seed yams are perishable and bulky to transport. Farmers who do not buy new seed yams usually set aside up to 30% of their harvest for planting the next year. Yam crops encounter pressure from a range of insect pests and fungal and viral diseases, as well as nematodes.

Their growth and dormant phases correspond respectively to the wet season and the dry season. For maximum yield, the yams need a humid tropical environment, with annual rainfall over 1,500 millimeters (59 in) distributed uniformly throughout the growing season. White, yellow, and water yams typically produce a single large tuber per year, generally weighing 5 to 10 kilograms (11 to 22 pounds).

Yams suffer from a couple of pests and diseases. There is an anthracnose caused by Colletotrichum gloeosporioides which is widely distributed around the world’s growing regions.[15] Winch et al., 1984 find C. gloeosporioides afflicts a large number of Dioscorea spp.

Despite the high labor requirements and production costs, consumer demand for yam is high in certain subregions of Africa,[1] making yam cultivation quite profitable to some farmers.

What are the Benefits of Yams in the Body?

Although they have less than sweet potatoes, yams offer you antioxidants, including vitamins A and C. These vitamins support a healthy immune system and fight free radical damage, while also combating inflammation.

It is a diet rich in vitamins A and C that help guide the skin, eyes, heart, brain, and more from damage.

Yam is one of the most widely consumed foods in Nigeria. It contains carbohydrates and can be eaten just like that or used as porridge, etc.