Let's watch together! The "Chinese Dove Flower" from the Ice Age

China is a vast country with rich resources and complex and changeable natural conditions, which has given birth to rich plant resources, many of which are ancient relict species in the northern hemisphere. Davidia involucrata is one of the typical representatives.

Part 1

Davidia involucrata - a "living fossil" in the plant world

During the Quaternary glacial period, due to the sharp drop in temperature, Davidia involucrata, which was once widely distributed throughout the world, became extinct one after another. It only survived in southwestern China, which was less affected by glacial activities, and became a unique Tertiary relict plant in my country.

Davidia involucrata is known as the "living fossil", "green panda" and "pearl in the forest" of the plant kingdom. It is listed in the list of rare and endangered plants in China and is a national first-class key protected wild plant.

Flowering Davidia involucrata plant (Image source: wikipedia-Rasbak)

Under natural conditions, Davidia involucrata is mainly distributed in the warm subtropical mountains in the Yangtze River Basin in western China. It often grows in moist evergreen broad-leaved and deciduous mixed forests at an altitude of 1250 to 2200 meters, and is mostly distributed in discontinuous, sporadic or small blocks.

Now scattered or small patches of natural forests can be seen in Shennongjia in Hubei, Fanjing Mountain in Guizhou, Emei Mountain in Sichuan, Zhangjiajie and Tianping Mountain in Hunan, and northwestern Yunnan Province.

However, after being introduced and cultivated all over the world, the current distribution range of Davidia involucrata has far exceeded the range of its natural preservation, and its location has gradually moved northward and the altitude has become lower and lower.

For example, in Beijing, the Davidia involucrata introduced and cultivated in the North Garden of the National Botanical Garden is blooming with beautiful white flowers.

Part 2

What you thought were petals are actually bracts

When the flowers of Davidia involucrata are in full bloom, they look like a white dove spreading its wings ready to fly, and are also known as the "Chinese Dove Flower". The transition between spring and summer is the flowering season of Davidia involucrata. From a distance, the "white flowers" of the tree dance in the wind, as if a flock of pigeons are flying in the sky. It is very spectacular and seems to convey the Chinese people's desire for world peace.

Figure: Davidia involucrata flowers in full bloom at Wuhan Botanical Garden, Chinese Academy of Sciences (Photo: Zhang Lijun)

However, this beautiful "white dove flower" is not the real flower of Davidia involucrata, but two naturally drooping white petal-shaped bracts.

It is a modified leaf that is initially light green, then turns milky white, and finally turns brown and falls off. The real flower is the dot-shaped purple-red flowers hidden under the two white bracts. These flowers gather together like a small brown-red ball.

Davidia involucrata flowers dancing like doves (Photo source: Wikipedia-Teg752)

In addition to white bracts, in April 2016, nearly 20 Davidia involucrata trees with pink bracts were discovered in Wangjia Town, Gong County, Yibin City, Sichuan Province for the first time in China. Their leaves are light scarlet. This provides important material for garden color arrangement and selection of ornamental varieties. It is just around the corner for the "pink pigeon" to enter the public eye.

The flowers of Davidia involucrata are small and inconspicuous, but the bright large bracts are eye-catching and easy to see. While protecting the pollen from being wetted by rain, they also attract insects to come and collect nectar and pollinate, thus completing the reproduction process.

Part 3

Scientific research and viewing

The research on Davidia involucrata has a history of more than 100 years since 1869, when a French missionary and biologist named Armand David first discovered it in Muping, Sichuan (now Baoxing County) and sent a specimen to the Natural History Museum in Paris.

French missionary David (Photo source: Wikipedia)

As a Tertiary relict plant native to my country, exploring the origin, evolution and reasons for its extinction has important scientific value in studying paleoflora, systematic development and paleogeographic environment.

At the same time, how to scientifically protect, develop and utilize Davidia involucrata is also an important task in promoting biodiversity conservation in my country.

The ancient and rare Davidia involucrata not only has important scientific research value, but also plays an important role in people's lives.

The plant can be used to appreciate its flowers and fruits, its seeds and peels can be used to press fragrant oil, its bark can be used to extract rubber or prepare activated carbon, its wood can be used as raw material for furniture and construction, and its flowers are a good source of nectar.

Today, the important scientific research value and extremely high garden ornamental value of Davidia involucrata have been recognized by the world. It is a valuable resource that is highly favored in my country and even the world. It is widely planted as an ornamental tree species in Europe and North America and is praised by the West as "the most beautiful tree in the northern temperate zone."

Part 4

What makes Davidia involucrata endangered?

It is precisely because of its economic value that Davidia involucrata is facing a threat to its survival. The wanton picking of wild seedlings, felling of trees, picking of unripe fruits, and the implementation of project development that damages the ecological environment have made it difficult to find seedlings grown naturally from Davidia involucrata seeds in the wild, causing fatal damage to it.

In addition to external reasons, there are many internal reasons for the Davidia involucrata that have caused its number to decline sharply, causing it to be on the brink of extinction.

First, its habitat is narrow. Davidia involucrata has strict requirements on the growth environment. When it is young, it prefers a shady environment; after middle age, it prefers more light, and insufficient light will also inhibit its growth.

Secondly, natural regeneration is difficult. Davidia involucrata regenerates naturally through two forms of reproduction: seed germination and root suckering (new shoots growing from the roots). After the seeds mature, they will experience a long dormant period. It usually takes 15 to 18 years for seed reproduction to bloom and bear fruit, and 20 to 25 years to enter the peak fruit-bearing period. Even if it bears fruit, the phenomenon of alternate bearing is very obvious, and early fruit drop is serious. There is a saying that "one fruit is produced for every thousand flowers."

Although the root sprouting reproduction method continuously expands the living space through group behavior and enhances the ability to resist adverse environments, thereby increasing the chance of survival, it limits the expansion range of Davidia involucrata and is not conducive to its spread.

Finally, the seed abortion phenomenon of Davidia involucrata is serious. In most cases, only 1 to 3 seeds in the kernel of Davidia involucrata are mature, and most embryos stop growing after a certain period of development. The serious abortion phenomenon greatly reduces the germination rate of seeds.

In order to protect Davidia involucrata, the state has established nature reserves in areas where it grows in large numbers to protect it in situ. By prohibiting indiscriminate logging and strengthening habitat protection, it ensures that Davidia involucrata crossbreeds, seeds germinate, and seedlings grow, so as to preserve the genetic diversity of Davidia involucrata to the greatest extent possible.

On the other hand, scientists have achieved artificial breeding technology through continuous research and practice. A large number of artificial introduction and cultivation practices have been carried out across the country, accumulating valuable experience for the ex situ conservation of Davidia involucrata, and gradually carrying out the adaptive domestication of Davidia involucrata to dry and hot climates, and conducting in-depth research on its endangered mechanism to protect its evolutionary potential.

After millions of years of vicissitudes, Davidia involucrata has witnessed the changes in paleogeography and paleoclimate. Currently, in terms of taxonomy, it is the only species in the genus Davidia family and is known as the direct descendant of the Tertiary flora.

The experience of Davidia involucrata being introduced by countries all over the world has made it like a fluttering white dove, carrying the motherland's mission of friendship and spreading the Chinese people's peace-loving desire around the world.

The graceful posture and precious value of Davidia involucrata deserve human's careful protection. Only by working together can our future generations appreciate the graceful posture of this ancient species.

References:

1. Chen Junshan. Living fossil of plants - Davidia involucrata[J]. China Forestry, 2007, 30-33.

2. Zhang Zhengyun, Su Zhixian, Shen Aiying. Biological characteristics, endangered causes and protection of Davidia involucrata, a plant endemic to China[J]. Journal of Huaiyin Teachers College (Natural Science Edition), 2003(2):66-69.

3. Luo Shijia. Genetic diversity and conservation biology of Davidia involucrata[D]. Huazhong Agricultural University, 2012.

4. Zhan Yuyan, Liu Yanhong, Xiong Wenjuan. Current status and prospects of research on the causes of endangered Davidia involucrata. Hubei Forestry Science and Technology 2021(1):41-43.

5. Flora of China http://www.iplant.cn

Produced by: Science Popularization China

Author: Cao Cheng'e (Wuhan Botanical Garden, Chinese Academy of Sciences)

Producer: China Science Expo

The article only represents the author's views and does not represent the position of China Science Expo

This article was first published in China Science Expo (kepubolan)

Please indicate the source of the public account when reprinting

Please indicate the source of the reprint. Reprinting without authorization is prohibited.

For reprint authorization, cooperation, and submission matters, please contact [email protected]