Can a 15 million-year-old flower bring us closer to the truth of flower evolution?
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Picture ① Restoration picture of Ding’s flowers Picture ② Amber interviewees containing Ding’s flowers 15 million years ago
For thousands of years, people have used poetry, songs, paintings, and video works to praise the fragrance and beauty of flowers and give them profound meanings.
However, botanists are thinking: Where did these beautiful flowers come from, and how did they evolve?
For more than a hundred years, Darwin’s theory of biological evolution has been deeply rooted in the hearts of the people, but the evolution of flowers has been a difficult question for botanists. The mystery of flower evolution has even been listed as one of 125 world-class scientific problems by Science magazine.
The botany community speculates that the flower is a longitudinally compressed branch.
This is recognized by many botanists and supported by modern botany research, but related fossil evidence has been absent.
The reporter learned from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences on October 10 that the paper "The unique fossils in the Miocene amber provide new enlightenment for the evolution of flowers" completed by an international team led by researcher Wang Xin from the institute was recently published in " Paleo Entomology.
They found a peculiar flower fossil in a piece of Domenican amber that was 15 million years ago-the five-digit Dinosaur flower.
The fossil clearly shows that the flower is a longitudinally compressed branch, which provides important evidence for the evolution of the flower.
Flowers are actually the reproductive organs of angiosperms
The reason why flowers have ornamental value is mainly due to their graceful, colorful petals.
Petals have also become one of the distinguishing characteristics of different flowers.
But in the eyes of botanists, a flower is just an organ for the reproduction of the next generation, so they pay more attention to the stamens and pistils that produce germ cells, which play an important role in the reproduction and evolution of flowers.
"A typical flower is generally composed of a flower stalk and a calyx, petals, and stamen attached to it. The stamen is divided into stamens and pistils." Wang Xin told the Science and Technology Daily reporter.
Those who have a little knowledge of botany will also find a strange phenomenon, some flowers have no petals, such as golden sage orchid.
What if Lin Dai buries flowers under the Yushu and encounters such flowers?
Looking at the plant evolution textbook, we will find that compared with the earth’s 4.5 billion years of history and the earliest plant mosses of hundreds of millions of years, the blooming time is not long, only about one or two billion years.
"The flowers that people now call are actually the reproductive organs of angiosperms. Before the emergence of angiosperms, mosses and ferns propagated by spores had grown on the earth for hundreds of millions of years." Wang Xin said.
Angiosperms, or flowering plants, are the kings of the plant world.
It is the most evolved, most diverse, most widely distributed, and most adaptable group in the plant kingdom today.
It is now known that there are more than 300,000 species of angiosperms in the world, accounting for the vast majority of the total number of plants.
From the perspective of modern genetics, the development of flowers is essentially controlled by several genes, which can be roughly divided into three types of genes that control calyx, petals and stamens. Scientists have proposed an ABC model of flower development based on genetics.
Different gene expression determines the general structure of the flowers of different groups of plants, and eventually develops into the floral world we see.
Mysterious amber fossil confirms scientific conjecture
In May 2002, the team of Researcher Sun Ge from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences published a paper in the journal Science, stating that they had discovered a fossil of a flowering plant about 125 million years ago and named it Ancient Chinese Fruit.
In people's eyes, Guguo is more like a herbaceous plant, because although it has the reproductive organs of flowers, it does not have colorful petals.
Different from modern flowers, its fruits and stamens are distributed on a long axis, which looks like a water plant.
Wang Xin told reporters: “There has been a saying in the botany community for a long time that the flower is a vertically compressed branch, but no relevant fossil evidence has been found. There is only one ancient fruit, which cannot describe the complete evolution history of the flower, so It is inevitable that some people will doubt their previous guesses."
However, with the joint efforts of five scholars from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences, Fujian Agriculture and Forestry University, the University of Vigo in Spain, and the Fushun Amber Research Institute in Liaoning, they discovered a strange kind of amber fossils about 15 million years ago. flower.
Wang Xin named it Ding's Flower.
Ding's flower fossil is very small, only 3-4 mm, inlaid in a piece of amber produced in the Miocene stratum in Domenica, Central America.
Due to the good preservation of amber and using modern advanced micro-CT technology, researchers can clearly observe the main characteristics of Ding's flowers: bracts, tepals, stamens and pistils connected to the flower axis.
To their surprise, unlike ordinary flowers whose calyx, petals, stamens, and pistils grow almost from the same point, this ancient flower seems to have undergone "longitudinal stretching". The various organs in the flower grow up and down one by one. Flowering branches.
Judging from the restoration map provided by Wang Xin, the flower has 5 interlocking tepals, 10 inwardly curved stamens, and a pistil with curved styles in the center.
Each stamen has a long filament with an anther containing 4 medicine chambers on top.
Ding's flower belongs to the common eudicotyledonous plant.
In 2018, the scientific research team led by Wang Xin discovered the static Zihua, which has traced the history of true dicot plants to the mid-Cretaceous about 100 million years ago, but how these flowers evolved has been lacking meaningful fossils. Evidence confirms and supports.
"Although the Ding's flower is relatively new, its unique shape shows for the first time that people's guesses about the nature of the flower for hundreds of years may be reasonable, that is, the flower is a vertically compressed branch." Wang Xin said.
Further reading
The Ding’s flower is named as a tribute to Mr. Ding Shisun
Wang Xin introduced that the fossil was named Ding Shihua in memory of the former president of Peking University and the famous Chinese mathematician Mr. Ding Shisun.
"We named this fossil flower from the ancient times by Ding's flower to pay tribute and comfort to President Ding Shisun. We thank him for using the democratic and scientific academic atmosphere and firm and persistent pursuit of life to help us solve world-class scientific puzzles. "Wang Xin said.
At present, this fossil that has solved a century of scientific conjecture is preserved in Fushun Amber Research Institute.
As a private institution, the Fushun Amber Research Institute can obtain Ding's flower amber fossils.
In the spring of 2011, colleagues from Shenzhen brought a Dominican amber distributor to Fushun Amber Research Institute, planning to sell a batch of amber specimens for research purposes.
The planned amber specimens did not make Fan Yong, director of the Fushun Amber Research Institute, shine, but he found a group of very rare flower specimens among the amber fossils ordered by other customers.
Fan Yong is sensitive to the important scientific value of these specimens and wants to stay for research.
But it was rejected by the Dominican dealer.
After tracking all the way, Fan Yong spent a week discussing with clients in Shenzhen and finally obtained several flower specimens.
In 2013, Wang Xin came to Fushun Amber Research Institute and found this peculiar flower specimen among numerous amber specimens, and he took it back to Nanjing for study with Fan Yong's permission.
After years of exploration and experimentation, Wang Xin and his team finally solved the mystery of flower evolution and launched major research results in paleontology in 2020.
"For a long time, people have always wanted to figure out how the flowers come. The discovery of Ding’s flowers provides us with a very important clue. This evidence and conclusion are not only conducive to confirming people’s interpretation of the essence of flowers, but also conducive to people’s understanding. Originally weird early angiosperm fossils (such as Liaoning Guguo, Yuhanguo). In the near future, we may be able to completely solve the mystery of the evolution of flowering." Wang Xin told reporters.
Our reporter Zhang Ye