Yam is a group of plants belonging to the dioscoreian family. Several species, united under this name, are distributed mainly in the subtropics and tropics of Latin America, Oceania, Africa and Asia. Some of them grow in warm temperate climates. Yam is also called dioscorea. The plant was named after the Greek physician and botanist Dioscorides.
Plant description
Yams are perennial herbaceous vines. The developed root system of the fibrous type is often intertwined with neighboring plants. In the area of the root neck of yams, characteristic lateral shoots 5-50 cm long are formed, which are called stolons. On one bush they can be from 4 to 20 pieces. Their length is a varietal characteristic, depending on it, yams can be loose, medium-fruited, sprawling or compact. At the ends of the stolons tubers are formed, it is them that are eaten.
The stems of the plant are braided only in one direction. Some species are characterized by creeping or erect stems. Sharp spikes are often present at the base of the shoots. The stem itself is thin and ribbed.
Some types of yams are characterized by the development of nodules in the axils of the leaves. Often, young shoots are lowered.
Leaves are simple, whole, articulated or lobed. Petiole is long, up to 12 cm. At the ground, the leaves are placed opposite, and the upper ones are arranged next. The leaf has a rounded heart-shaped shape, and is sharpened in the apex. In diameter, it reaches 6 cm. All veins that go from the point of joint, then diverge across the width of the sheet. They are brought together at the top, creating a relief pattern.
Dioscorea very rarely blooms. Yams is a dioecious plant. But experts argue that the rudimentarily heterogeneous parts can be located on the same plant. Most often, inflorescences of yams are drooping, simple or complex. The flowers are small, can be either single or paired, spike-like or racemose.
The fruit is a dry box, divided inside into three compartments. Each nest contains up to six flat seeds with wings. It opens when it matures. The dry shell bursts and the berries fall out.
Yams: vegetable or not
This plant is actively eaten in Africa. Nigeria is considered the largest producer of yams in the world. There, this plant is considered the food of fishermen.
For the first time, they began to grow it in Asia and Africa, according to some reports, more than 5000 years ago. The plant is very important for these rather poor regions. After all, here yams are considered the main source of food for many people. But today, large plantations of this plant are also grown in Oceania and Latin America.
Yam in these regions is considered a crop. He is valued for fleshy tubers. For agricultural purposes, only a few types of yams are used:
- white;
- yellow;
- Chinese;
- winged;
- edible;
- bulbous;
- three-cut.
All cultivars underwent lengthy selection, because the tubers of the wild representative of this family have a bitter taste. Interestingly, the tubers of any yam contain toxic substances. They are destroyed during heat treatment.
Yam is a meaty vegetable. One such spine can weigh up to 70 kg, and its length can be more than 2.5 m. However, as a rule, the average yams tubers weigh much less: from 50 g to 15 kg.
Root crops have an elongated oval, round or fusiform shape. The surface is smooth, small cracks may be present. The skin of the tubers may be pink, white or purple, depending on the plant variety. It is thin, almost the same as that of potatoes.
Yams is a plant that needs heat. You can get a good harvest of dioscorea only in conditions of the tropics and subtropics.
Popular views
Modern botanists attribute more than 600 species to the genus Dioscorea. Experts recommend using the following in the middle lane:
- Caucasian;
- nippons;
- Balkan.
Caucasian
Caucasian Dioscorea is a relic plant. The birthplace of this yam is Western Transcaucasia. The plant grows among shrubs, at the edges of the forest. Dislocation in such a place is obvious, because plants have poor competitiveness, since the root grows only 7 cm per year.
With support, perennial thin vines can grow up to 4 m in height. The lower leaves are whorled with a dull surface. A relief pattern of veins is applied on them. The shape is oval, heart-shaped. The upper leaves from the stem are disconnected by long petioles, located opposite. They have a pointed apex, and the edge is slightly notched.
Diverse flowers are inconspicuous, small in size, yellow-green in color. Flowers are collected either in a brush or in ears of corn. Flowering occurs in late spring - early summer. The fruit of the Caucasian yam is a three-nested dry box.
The rhizome is thick, located horizontally, has many sleeping kidneys.
In the middle zone, this species shows winter hardiness. The root crop of the Caucasian dioscorea has a high level of saponins in comparison with other species. This substance (steroid glycosides) is used for the manufacture of various medications.
Diosgenin-based drugs in traditional medicine are prescribed for women to synthesize progesterone. It is also used in the treatment of atherosclerosis, because saponins are able to bind cholesterol. Yams is an important plant. It is often used for insect bites (including poisonous ones) in countries where the plant grows in the natural environment.
Nippon Dioscorea
Mixed forests of the warm temperature zone of Japan and Korea are the birthplace of Nippon dioscorea. The root grows in a horizontal plane, reaches a thickness of 1.5 cm.
The green trunk is thin, braided around the support to the left side. The leaves are simple, placed next. Petioles up to 20 cm long. The surface of the leaves is shiny, green. The shape can be different - from palmate-uneven, pointed to the top, to broad heart-shaped.
Balkan
Dioscorea Balkan is the only plant of the whole genus that grows on the Balkan Peninsula. This species is protected, as it is on the verge of extinction. It reaches two meters in height in captivity, and in natural conditions - up to 5 m. In autumn, the leaves die off, and new shoots grow in the spring.
Yams is a plant demanding heat; it is characterized by a long vegetative period. Therefore, in our country it does not grow. But experienced gardeners do not stop experimenting.
Useful properties of the plant
Today, many are interested in an amazing plant - the Caucasian dioscorea. The use and contraindications should be studied before purchasing any drug based on it.
Scientists have proven that eating this root vegetable in food helps to lower cholesterol in the blood. The walls of the blood vessels strengthen. It also has a positive effect on blood composition. The use of the product helps to dissolve atherosclerotic plaques and normalize blood pressure.
Caucasian Dioscorea is used as a raw material for the production of diascorin alkaloid, from which medicines are made. This substance is most often used for the manufacture of medicines for women. After all, it normalizes hormonal balance, promotes the production of estrogen. Diascorin is also the main substance for most contraceptives.
Dioscorea is used in the manufacture of dietary supplements.
In America, yam-based drugs are used to treat gout and rheumatoid arthritis. They show high efficiency in the recovery of the body after strokes and heart attacks.
Contraindications to the use of yams
The use and contraindications of Caucasian dioscorea should be definitely studied. After all, it should be remembered that this plant contains poisonous substances and in an untreated state it is strictly forbidden to use it. Otherwise, it can cause digestive upset or the development of kidney disease, liver and gastrointestinal tract.
It is forbidden to abuse this product, because its excess can lead to vomiting and diarrhea.
Experts prohibit the use of this plant in food by patients with:
- an ulcer of the stomach and intestines;
- gallstone disease;
- cholecystitis;
- hepatitis.
Conclusion
Dioscorea is a climbing plant that is common in the tropics and subtropics. Some of its species are actively used in food. Various medicines are made from the Caucasian dioscorea. Yams are also used in the arrangement of a personal plot.