Albizia can't live for more than 50 years but never die.

The year before last, a small acacia seedling suddenly grew in my yard, which made me wonder. The nearest acacia tree from my home can be 200 meters away, and they basically do not rely on birds to spread seeds. How did they come to my yard? Let's just say the seed was blown by a strong wind.

Have no idea what Hehuan looks like? Look at this picture. You must know it. Picture: 4028mdk09 / wiki commons

This acacia tree has grown as tall as I am in just a few months. It was only then that I remembered to remove it, but it was too deep to dig out and had to be cut off from the ground. Unexpectedly, it produced branches again last year and surpassed the height of the year before in one growing season. Coincidentally, in this year's yard renovation, one or two trees that blossomed in summer were needed, and they were in the right position, so they stayed. This year, its height and crown width have reached 2.5 meters. Although it has not yet reached the age of flowering, it has a faint temperament of summer shade.

It is this little acacia tree of unknown origin. Picture: frost moth

A joyful acacia tree

Although it is summer flowers and trees, but Hehuan always has a touch of spring. The word "Hehuan" has two meanings: one is for everyone to get together and happy, and the other is for men and women. In ancient times, Albizia often referred to the former meaning.

Western Jin Ji Kang's "Health Preservation Theory" said: "Hemerocallis forgets worries, joys together and resents." In ancient literature, Hemerocallis is often compared with Hemerocallis. The ancients thought that Hemerocallis could make people forget sorrow, and it had a similar effect, removing resentment and calming the mood.

Cui Bao "Ancient and Modern Note" cloud: "if you want to make people angry, you will give them blue clothes." Green clothes, Hehuan also. The removal of the plant makes people resentful. " It means that if you do something sorry to your little friend, go and send a handful of acacia flowers as soon as possible, you can dispel Ta's anger and play happily together again. Everyone is happy. If you simply give him a tree and plant it in the yard, the effect will be even better.

Would anyone be angry to see such a tree? Picture: armaghangiah.com

Albizia leaves that open and close in the twilight

Another ancient name of Hehuan is Zuo Hehui, also known as Night Hop. The ancients have long discovered that Albizia is night-sensitive: when the sky is dark in the evening, its bipinnately compound leaves will close, its pinnae will close toward the main leaf axis, and the leaflets will droop and close in pairs.

Bipinnately compound leaves of albizzia. Original drawing: Gmihail / wiki commons; Chinese: hannah

The principle of nocturnal sensitivity is that the structures of the cells on the upper and lower sides of the pinna and the base of the leaflet are different; when the cell plasma membrane and tonoplast feel the change of light, it will bring different turgor and pressure changes to the cells on both sides, so that the pinnae and leaflets bend in a certain direction.

When the night comes, the leaflets will close in pairs and the pinnae will close. Picture: Trees That Please Nursery

Li Yu, an amorous genius in the Qing Dynasty, preferred the second explanation of Hehuan, that is, the matter between men and women. "Leisure occasionally" cloud: "this tree opens and closes at dusk, and every time it turns yellow, the branches and leaves intersect with each other, which is a famous acacia."

The leaves of Acacia "open and close at night". Picture: pixabay

Li Yu believes that it is unreliable for day lilies to forget their worries, but Hehuan has real benefits, so Hemerocallis can not be planted, it must be planted, and it must be planted near the husband and wife's bedroom-- this so-called "the flowers of Hehuan should be placed in the place of Hehuan." When husband and wife are separated or combined, they should be synchronized with the opening or closing of the leaves of acacia. This is good for both people and trees. "people open and trees open, trees close and people close. People not only make it happier, but also make the trees grow more luxuriant, as the so-called people are suitable for the land. " He also thinks that it is best to water the acacia tree with overnight bath water, and vows that this method is effective for me. If you don't believe me, plant two trees and compare them.

The bark of Hexinzhi

There is a third term for the name of Acacia, which is about the medicinal value of its bark. The Compendium of Materia Medica records that the skin of Hehuan "calms the five internal organs, and the mind makes people happy and carefree". Its theory probably comes from the leaves of Albizia paniculata, which opens and closes day and night, adapting to the so-called "growth and decline of yin and yang", so it is believed that it can calm the mind and treat depression and insomnia.

The acacia tree during the day. Picture: Cs?rf?ly D / wiki commons

The Yuzhi of female Red written by Longfu in the Yuan Dynasty recorded a man named du Liao whose wife Zhao would pick some albizzia flowers and put them in her pillow during the Dragon Boat Festival every year. When du Lamb was in a bad mood, Zhao took a few albizzia flowers and put them in the wine and asked the servant girl to give him a drink. I think it's not Hehuan that makes him feel good, but wine and servant girl.

Looking at such flowers will probably make people feel better. Picture: Pixabay

A short-lived but immortal acacia tree

Albizia is a popular street tree because it can provide lovely flowers and thick shade in early summer. And it grows quite fast, just like the one in my yard, which can grow to nearly 2 meters in one growing season. It is expected to grow to 6 meters within 6 years, with a DBH of 15cm, which is a qualified courtyard tree. 10 to 20 years later, it can be as high as 15 meters and have a shady area of 200 square meters, but at this age, its life is coming to an end.

As an acacia of street trees, tall trees, thick shades and lovely flowers make it very popular. Picture: Fanghong / flickr

Unlike ornamental trees that often live for hundreds of years, Albizia has a short life span of about 25 years, with a maximum of no more than 50 years, which has nothing to do with its large size. The reason is that Acacia is more vulnerable to a fungal infection, leading to wilt. The Albizzia street tree in my hometown is about ten years old, and about half of the branches on the crown are dead. And the branches of albizzia are fragile, which makes it easy to be hurt by wind and rain.

Although the aboveground part is short-lived, the sprouting ability and growth rate make up for this, and its roots are fully capable of sprouting a large number of seedlings before the trunk dies, and grow to the size of the trunk within a few years. In this sense, Acacia never dies, but continues to clone.

Old trees infected by fungi, tillering seedlings with long roots, and close-range seed seedlings. Original: invasive.org; annotations: hannah

The seeds of albizzia are also very strong, and the pods can be spread to a distance of 100 meters with the help of the wind (that may be where the one in my yard came from), and the seeds can still germinate after decades of dormancy. Acacia life is short and explosive, and it is classified as an invasive plant in many countries.

Pods of acacia. Picture: treegrow / flickr

Dried pods and seeds of albizzia. Picture: Finca la Casilla / flickr

Pink hair ball-like acacia flower

There are about 150 species of the genus Acacia, which are widely distributed in tropical and subtropical regions. Albizia julibrissin is the only species distributed in the Northern Hemisphere, its origin spans the whole of Asia, as far as Turkey in the west and the Korean Peninsula in the east.

In the Ten Jun Dog Picture painted by Lang Shining of the Qing Dynasty, the background of Xuezao Lu is a tree of albizzia. Picture: wiki commons

Acacia entered the western world relatively late. In 1745, Florentine naturalist Filippo degli Albizzi introduced it to Europe from Constantinople and to North America in the same year. Filippo was a fallen aristocrat in Florence, and his ancestors were once rich-the Albizzi family was the center of Florence oligarchy in the 14th century until the rise of the Medici family in 1434. I don't think that more than 400 years later, this family name will become the generic name of the genus Acacia, but it will be immortal in the plant world.

The mansion of the Albizzi family, who were once competitors of the Medici family. Picture: sailko / wiki commons

Because Albizia enters Europe from West Asia, and because its flowers are in the shape of silk, Westerners call it Persian silk tree, and this silk is the main ornamental part. The single flower of Acacia is very small, and the Corolla and calyx add up to less than 1cm, forming a long tube, but pink stamens can be as long as 3cm. Most florets gather together to form a head, and their stamens form pink hair balls.

The flowers of the genus Albizia are of inconspicuous dimorphism. In a head, the central flower usually has longer, brighter filaments. These flowers are sterile and are only used to attract pollinating insects and hummingbirds with long beaks. While the edge flowers are shorter and the filaments are lighter, this part is used for sturdiness.

Photo: Philmarin / wikipedia; Chinese: frost moth

Relatives and varieties of albizzia

Plants of the mimosa subfamily all have hairball-like inflorescences, which makes it difficult to distinguish. For example, in North America, Acacia is often called mimosa, while mimosa in English refers to both mimosa Mimosa and sometimes acacia Acacia.

What is the key to separate them from Albizia? Mimosa is dominated by herbs or shrubs, with few trees, and the single flower stamens of Mimosa are generally no more than 10. And the flowers of Acacia must be yellow.

The compound leaves of mimosa Mimosa pudica usually have only 2 pairs of pinnae (4 pinnae). Picture: tohumlar.net

A. julibrissin has many horticultural varieties, such as the purple leaf variety "Summer Chocolate". There is also the more famous "Ernest Wilson", which was introduced to America from South Korea by the famous plant hunter Ernest Wilson. This variety is characterized by its short stature and is often planted as a potted plant in Japan. It is called Sleeping Tree.

Purple leaf variety 'Summer Chocolate'. Picture: arbresetplantes.fr

In haiku, Hehuan is one of the seasonal words that represent summer. Whether it is the stamens moved by the red silk in the moonlight, or the leaves that close quietly in the quiet, will bring people into a beautiful midsummer night's dream.

This is the 164th article in the fourth year of the species calendar, from the author of the species calendar @ frost moth.

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