There are more than a dozen kinds of red beans, which one is the real "acacia bean"?

Author: Ye Jianfei

The article comes from the Science Academy official account (ID: kexuedayuan)

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When I was young, I read the poems "Red beans grow in the south, and spring brings a few branches", "The exquisite dice are filled with red beans, do you know how deep my love for you is?" I was puzzled: Aren't these red beans grown in the fields? Why are they said to grow in the south? How can such ordinary red beans used for cooking porridge and making red bean paste be so closely related to love?

Later I realized that the red beans grown in the south and the red beans used as porridge fillings are indeed not the same plant.

There are more than a dozen kinds of red beans?

If you check the relevant plant name database, you will find that there are more than a dozen plants named red beans. So which one is it that is sung in ancient and modern poems?

Although time has passed, we cannot know exactly which plant Wang Wei was referring to. However, based on the phrase "a few branches sprout in spring", we can be sure that the acacia beans are a woody plant of the legume family, while the red beans commonly eaten by ordinary people are the seeds of the herbaceous plants Vigna angularis and Vigna umbellate of the legume family.

There is a lot of debate about what kind of plant Acacia red beans are. Guo Moruo, the first president of the Chinese Academy of Sciences, and Professor Wang Jinwu of Peking University have all studied this plant. However, there are many different opinions.

"Lover's Tears" Acacia

Ancient people often regarded Abrus precatorius as red beans. As early as in the "Tang Materia Medica", the two were regarded as the same plant. Later, "Guang Qunfangpu" and "Plant Names and Realities Illustrations" also had this statement.

Abrus precatorius is a woody vine with light pink or purple flowers and red seeds with a small black spot on the bottom, also known as "black mouth" or "lover's tears".

However, the legend about red beans is somewhat different from that about acacia seeds: In ancient times, a man went to war, and his wife prayed and cried under a tree on a high mountain day and night. After her tears dried up, she bled, and the blood turned into red beans, took root, sprouted, and grew into a big tree. From this, we know that "red beans" should be a kind of tree, but in reality, acacia seeds are vines, so it is still necessary to consider whether "acacia seeds are red beans".

Acacia chinensis, which climbs up the stems of other plants, is a vine (from the Chinese Plant Image Database, photo by Situ Huimiao)

Although the acacia bean is beautiful, it is very dangerous. Its roots and leaves are poisonous, and the seeds are even more poisonous. A broken seed can kill a person. Eating it or it coming into contact with wounds can cause poisoning.

Are the jewelry made of acacia seeds that are often seen in the market dangerous?

It turns out that the toxic protein of the acacia bean is mainly found in the cotyledons. As long as the seed coat is not broken, there will be no danger. The seed coat is hard and thick and not easy to break, so even if the whole bean is swallowed, it will not endanger life. However, if the seed coat is damaged by drilling or cutting during the jewelry processing, the consequences will be disastrous if it is accidentally ingested.

"Heart to Heart" Sea Red Bean

Mr. Guo Moruo believed that the red beans in Wang Wei's poem refer to sea red beans (Adenanthera microsperma).

Fruits and flowers of the sea red bean (from the Chinese Plant Image Database, photographed by Situ Huimiao)

Sea red bean is a small deciduous tree, commonly found in Lingnan region of my country, with small white or light yellow flowers, hard and non-corrosive seeds, blood red in color, bright and glittering, and a small heart-shaped shape, just like a beating heart, and there is a lighter heart-shaped pattern on the inner edge of the seed, which is called "heart to heart". Moreover, it is not easy to fade or rot, just like a faithful love, which lasts forever.

Compared with the black-mouthed acacia seeds, these characteristics of sea red bean seeds are more consistent with acacia red beans.

Orchidaceae

Professor Wang Jinwu believes that Acacia red beans are the red bean tree (Ormosia hosiei) of the genus Ormosia and its closely related species.

The red bean tree is a tall tree. Among the several "red bean" plants, it has the highest distribution latitude and can be found in southern Shaanxi, southeastern Gansu, Hubei, Sichuan, Jiangsu and other places in my country. Compared with the other two "red beans", the ancients had more opportunities to see the red bean tree, and it was more likely to be passed on as a token of love.

Seeds of the red bean tree (from the Chinese Plant Image Library, photographed by Chen Binghua)

Wang Wei was from Shanxi. You know, in the eyes of northerners, the area south of the Yangtze River can be called the south. Therefore, the South Country Wang Wei referred to was not necessarily Lingnan. And we have no way of knowing whether Wang Wei himself had seen "red beans". Therefore, Professor Wang Jinwu's statement that "red bean tree is red beans" is also reasonable and well-founded.

Red beans in the atmosphere of fireworks

After talking about the red beans in poems, let’s talk about the red beans on the dinner table. Although they have nothing to do with love, they are closely related to the daily life of food, rice, oil and salt.

One of them is the adzuki bean (Vigna angularis) of the genus Vigna in the legume family, which is the main ingredient for sweet bean paste filling. Adzuki bean is an annual herb with slightly flat seeds, 4-6 mm in diameter, and is very common in fields.

Adzuki beans (from the Chinese Plant Image Database, photographed by Bai Chongyan)

The second is adzuki bean (Vigna umbellate), which, as its name suggests, is smaller than adzuki beans and is also an annual herbaceous plant of the genus Vigna. The seeds are slightly cylindrical, 5-7 mm long and 3-5 mm in diameter. They are good for strengthening the spleen and removing dampness, clearing away heat and detoxifying. The economic value of adzuki beans ranks first among the five cereals, and they are also known as "golden beans".

Adzuki bean (from the Chinese Plant Image Database, photographed by Zhang Yazhou)

Speaking of this, can you tell the difference between the various types of red beans?