Yam (vegetable)

A yam is a food from a plant.

It grows under the dirt. The skin is rough. The inside can be white or purple.

Many yams grow on long vines. These vines can grow very big. The plant grows in warm lands. Some yams grow in Africa and Asia.

Farmers plant parts of the yam in the dirt. They wait for the rain to help it grow. It takes many months to grow. Some yams take a whole year!

People cook yams to make them soft. You can boil or fry them. In Africa, people mash them into a paste. This is a tasty meal.

Many people around the world love yams. They are a very important food.

A yam is a food from a plant.

It grows as a starchy tuber under the ground. The plant is a vine that grows in warm places.

Yams are native to Africa, Asia, and the Americas.

There are many kinds of yams. Some have rough skin that is hard to peel. The inside can be white, yellow, or even purple.

In Africa, the white yam and yellow yam are very important. People often mash them into a paste. This dish is called Iyan.

Farmers work hard to grow yams. They plant them at the start of the rainy season. Most yams grow in Africa.

It takes many months for the tubers to grow. Some yams take a full year to be ready. Farmers often use wooden tools to dig them up. This helps keep the fragile yams safe. Some yams, like the Chinese yam, can grow in cooler places too. They are used for food and even medicine.

Yams are amazing plants that grow as starchy tubers under the soil.

These plants are vigorous vines that grow in many warm parts of the world. They are native to Africa, Asia, and the Americas. There are about 870 different species of yams known to us. While many are delicious to eat, some species are actually toxic.

Most yams have a rough skin that is hard to peel. However, the inside becomes very soft once you cook it. The flesh can be white, yellow, purple, or even pink.

Growing yams is a big job that follows the seasons.

Farmers start a crop by planting seed tubers in mounds or ridges. This usually happens at the beginning of the rainy season. The plants need a humid environment with plenty of rain. Most yams grow during the wet season and rest during the dry season. A single large tuber might weigh several kilograms.

Some farmers in West Africa grow yams alongside other vegetables and cereals. This way of farming is called intercropping.

Humans have been growing yams for a very long time.

Three different species were grown by people on three different continents. In Africa, people domesticated the *Dioscorea rotundata*. In Asia, they grew *Dioscorea alata*. In South America, they cultivated *Dioscorea trifida*. The name "yam" might come from the Portuguese word *inhame*. This word likely came from Fula, a language in West Africa. It is a name that has traveled across the whole world.

Many different types of yams are important to different cultures.

In Africa, the white and yellow yams are the most important. People often pound them into a paste to make a dish called Iyan. The *Dioscorea alata*, or purple yam, is grown in many places. It was even carried by seafaring people to many Pacific islands. In China, the *Dioscorea polystachya* grows in cooler weather.

This Chinese yam is used for food and traditional medicines. Some yams, like the air potato, grow small bulbils on their leaves.

It is easy to get yams mixed up with other foods.

In the United States, people often call sweet potatoes "yams." In Australia, people once ate the tubers of the yam daisy. In New Zealand, a root called oca is often called a yam. In Malaysia and Singapore, the name refers to the taro plant. Even though the names change, these foods are all very special.

They provide important food for many people around the globe.

Yams are starchy, edible tubers produced by plants in the genus *Dioscorea*.

These plants belong to the Dioscoreaceae family and are monocots, making them relatives of grasses and lilies. Most yams grow as vigorous, perennial herbaceous vines. While there are approximately 870 known species, only a few are widely cultivated for food. Other species, such as *Dioscorea communis*, are toxic and cannot be eaten. The tubers themselves vary greatly in appearance due to many different cultivars. They often feature a rough, difficult-to-peel skin that ranges from light pink to dark brown. Once cooked, the inner flesh softens and can appear white, yellow, purple, or pink.

Cultivating yams requires specific environmental conditions and significant physical labor. The process begins at the start of the rainy season. Farmers plant whole seed tubers or tuber portions into mounds or ridges. The success of the yield depends on several factors. These include the size of the mounds and the spacing between plants. Farmers must also provide stakes for the climbing vines to grow upon. Because seed yams are bulky and perishable, farmers often save up to 30% of their harvest for next year's planting. Most yams require a humid tropical environment. They need annual rainfall that is distributed uniformly throughout the growing season. The plants follow a seasonal cycle where growth occurs in the wet season and dormancy occurs in the dry season.

Different species of yams have been domesticated independently across three continents. In Africa, humans domesticated *Dioscorea rotundata*. In Asia, the species *Dioscorea alata* was domesticated. In South America, people cultivated *Dioscorea trifida*. This long history of cultivation has spread yams to many temperate and tropical regions. The name "yam" likely derives from the Portuguese word *inhame* or Spanish *ñame*. These terms originated from Fula, a West African language used during trade. Interestingly, in Portuguese, the name often refers to the taro plant rather than *Dioscorea*. In many regions, the term "yam" is applied to unrelated vegetables. For example, many people in the United States call sweet potatoes "yams." In New Zealand, the oca is often called a yam, while in Malaysia, the name refers to taro.

In West Africa, the most economically important species are the yellow yam (*Dioscorea cayennensis*) and the white yam (*Dioscorea cayennensis subsp. rotundata*).

There are over 200 varieties of these yams. The white yam has a cylindrical shape and firm white flesh. The yellow yam contains carotenoids, which give the flesh its yellow color. The yellow yam also has a longer vegetation period and a shorter dormancy period than the white yam. These plants are large, with vines that can reach 10 meters in length. The tubers often weigh about 1 kilogram, though some can reach 5 kilograms. In Africa, these are frequently pounded into a paste to create a traditional dish called Iyan.

*Dioscorea alata*, known as the purple yam or water yam, has the largest global distribution of any cultivated yam.

It was first cultivated in Southeast Asia. It is grown across Asia, the Pacific islands, Africa, and the West Indies. This species was vital to seafaring Austronesian cultures. They carried these plants as "canoe plants" during migrations from Island Southeast Asia to Polynesia and Madagascar. The flesh of the *D. alata* tuber is typically white and has a watery texture.

Another important variety is the Chinese yam, *Dioscorea polystachya*. Native to China, this plant is more tolerant of frost and grows in cooler conditions. It is cultivated in Korea and Japan as well. Some varieties are used in traditional medicines or to make noodles.

Some species of the genus offer unique growth habits or challenges. The air potato, *Dioscorea bulbifera*, produces edible bulbils at the base of its leaves.

These bulbils are about the size of potatoes. While they can be eaten, some varieties require boiling or soaking to remove toxins. In Florida, the air potato has become an invasive species. It grows rapidly and crowds out native plants. It is difficult to remove because it can regrow from tubers or bulbils even after being burned. Another species, *Dioscorea dumetorum*, is known as the bitter yam. It is popular in West Africa because it requires less labor to grow. However, wild forms are highly toxic and have been used for criminal purposes or to poison animals.

Harvesting yams is a demanding task that requires great care. In West Africa, farmers typically use sticks, spades, or diggers by hand. They often prefer wooden tools over metal tools. This is because metal is more likely to damage the fragile tubers. The work is physically taxing, requiring farmers to stand, bend, squat, or sit for long periods. The depth of the tuber in the soil affects how much effort is needed. Despite the high costs and labor, consumer demand remains very high. In many subregions of Africa, yam cultivation is a highly profitable venture for farmers.