Behind the gorgeous flowers, there is a brutal evolutionary mechanism.
Around the rugged mountain roads, there are strange cycads. They seem to grow precariously on the hillside. Their twisted trunks, their specially jagged leaves, and their orange fruit, perhaps the strangest of the trees.
Cycad, she is the hereditary chief of the Borobodo tribe (after the rain) in Limpopo Province, South Africa. This is the most prosperous cycad in the world. They are said to be protected by magic after the rain. Whether it's magic or something else, what these strange plants need most is protection against the destruction of greedy predators. In fact, long before humans threatened their security, the cycads had a much more serious problem — an order of magnitude challenge.
You travel 150 million years ago and you'll see an odd number of cycads of all sizes and shapes on Earth and their closest relatives, conifers. These two plants are archaeoptophans that originated 360 million years ago. Gymnosperms have ruled the planet for 250 million years, but their glorious reign is long over. Many gymnosperm species have gone extinct, and these survivors are severely marginalized in the plant ecosystem. Conifers can only dominate in harsh northern forests and some marginal habitats, especially cycads.
The decline of gymnosperms is accompanied by the astonishing rise of angiosperms, a new power.
Angiosperms, also known as flowering plants, are the most powerful flora in the world. They provide food and shelter for countless creatures, including humans.
They are the "colonizers" in nature, and they have many tenacious varieties of life, with about 310,000 species of angiosperms and only 1,000 species of gymnosperms. Although the "qualifications" of flowering plants are shallow, they catch up from behind; it was born in a humble environment and occupied the largest area in the world during the Cretaceous period (65 million to 145 million years ago).
Angiosperms have puzzled scientists for more than 100 years, and Darwin once said they were a "troublesome mystery." In recent years, the research of botanists has gradually filled many gaps. It was found that the "dynastic succession" of plants was not as abrupt as previously thought; however, once the reform process began, it would move forward at lightning speed.
Just 30 years ago, flower fossils were difficult to find. Prior to this, it was predicted that primitive flowering plants would have lived about 100 million years ago, including large flowers like magnolias (because magnolias are the most primitive of angiosperms). All these imaginations ended in 1981. In 1981, a large number of 83 million-year-old flower fossils were first discovered in a clay mine in Assen, Switzerland. The discovery sheds light on the mystery of why fossil flowers are rare: they are very different in size than magnolias.
The discoverer of plant fossil flowers, the secret of its success lies in the method of their use. The new method screened a large number of soft deposits, and eventually thousands of well-preserved small flower fossils emerged. At this time, the flower fossils that countless people were looking for appeared in front of them, and the number was very large. These flowers, which are only one to two millimeters, are close relatives of plants such as walnuts, plane trees, and tiger ear grass. In forest fires, they were turned into charcoal and preserved.
Inspired by this, other scientific groups have also begun to study smaller flowers. Many fossils of small flowers have been found around the world, including those from 112 million years ago.
However, this is not yet the plant fossil of the oldest flower. Laurel is a pond weed that bloomed 125 million years ago. It was found in sediments in Yi County, northeast China in 1998. The Rehe area, where Yixian is located, was once famous in science for dinosaur feather fossils, but now the fossils of ancient plants there are no less than inferior.
Ancient laurel grows in ponds, and its flowers bloom on the water. However, you may not recognize them as flowers. Because the ancient fruit plants had not yet evolved at that time, people thought of the gorgeous organs of flowers. Nevertheless, ancient fruits, their tiny plant genitalia can also prove that they are angiosperms. Because its female reproductive organs are completely wrapped in a protective fleshy structure, the heart skin; the closed heart skin is the characteristic that determines the flowering plant.
It is this kind of sexual reproductive evolution that makes angiosperms ahead of other plants, and in the growth and development of flowers, the sperm of pollen must pass through the heart skin to reach the egg cells. Once inside the heart skin, a process called "double fertilization" begins. After the sperm binds to the egg cell, another sperm binds to the adjacent cell of the egg cell, and it will develop into the embryo's nutritious food in the future.
"Double fertilization" is the most unique "secret" of angiosperms, they have two obvious evolutionary trends, the first is that embryonic development and food supply rooms start at the same time, and then grow much faster than gymnosperms, in addition, the nutrition group can only begin to develop after fertilization.
On the contrary, the seeds of gymnosperms, some of which are in the pine cone, are filled with a lot of nutrients before fertilization, which greatly prolongs their reproductive process. It also means that every seed must have good food reserves, regardless of whether fertilization is successful or not. The angiosperm flower strategy wins at the starting line.
"Ancient fruit" may be the oldest fossil angiosperm, but it may not be the earliest angiosperm. To travel back in time to a more distant time, we must look for more hidden evidence.
One of the pieces of evidence is pollen.
A wide variety of pollen fossils can often be seen in sedimentary rocks, including, of course, pollen endemic to flowering plants. At present, the oldest pollen identified as angiosperm has been 135 million years old. This small pinch of precious pollen comes from sediments from the south of England. But angiosperms have less pollen than gymnosperms. In the words of one botanist: "When flowering plants first appeared, the amount of pollen was small and the type was small. This is called low status. Conifers, cycads and their extinct "relatives and friends" were the main plants of the year.
Genes open another door to the past.
As early as 20 years ago, scientists obtained the "development tree" of angiosperms by rigorously analyzing the DNA sequences of hundreds of extant plants. The analysis showed that Amborella is a rare evergreen shrub with small milky flowers and red berries, and is the earliest surviving angiosperm. Therefore, such a plant it is likely to preserve the characteristics of the family.
Coleus plum is the earliest flowering plant, found only in New Caledonia in the South Pacific. It was very fortuitous that it survived. The "New Caledonia Continent" was once part of the southern part of the Gonwana supercontinent, which broke away from the supercontinent 55 million years ago; as a result, when other ancient plant species lost their competitiveness and became extinct in these places, the island became the last "Super Noah's Ark" when other ancient plant species lost their competitiveness in these places.
Further genetic studies found that water lilies and their associated species, drainage grasses and magnolia vines (including the famous spice star anise) are almost as old as cophyllus plums. These more "noble" extant plant species can fill in some gaps, and there is a question: how did flowering plants evolve, because gymnosperms are the ancestors of angiosperms, because only they have strange seeds like angiosperms; but from what kind of plants did the rate of evolution begin? Candidates include extinct plants, absolute cycads and palm-like open orders. While no final conclusions have yet been reached, recent studies of extant plants have taken another step toward revealing the truth.
Botanist William Friedman spent 12 years studying primitive angiosperms. In 2020, he and his colleague Joseph Williams discovered that water lilies and magnolias have some special embryonic vegetative tissue that looks like gymnosperms. Thus, these two plants may constitute a "lost link" between angiosperms and gymnosperms.
Since then, Friedman's research has made greater progress. He found that the seeds of a special drainage grass would have nutritious support before fertilization. In other words, like gymnosperms, it is wasteful reproduction, that is, whether it is fertilized or not, it will first fill the seeds with food. Friedman said: "Our study fills the gap between angiosperms and gymnosperms. ”
Wherever angiosperms evolved, their evolution time was suggested by DNA sequence data that appeared earlier than the pollen record showed. A group led by Doug Soltis of the University of Florida in the United States believes that the earliest flowering plants may have occurred in the early Jurassic Period, 180 million years ago.
These simple new creatures had little effect at the time. After another 50 million years, the main angiosperm lineage finally appeared in the Late Jurassic.
Some botanists believe that from 144 million years ago to 140 million years ago, plants suddenly underwent explosive evolution, producing the main lineage of all flowering plants. They look so fast, it's shocking. Here angiosperms begin the conquest of the world.
In fact, from 110 million years ago to 90 million years ago, with the emergence of flowering rose branches, ecological rules also arose. Researchers at the Florida Museum of Natural History say that the simultaneous evolution and development of various rose branches means angiosperms are growing around the world.
Among an angiosperms, some trees mostly belong to the rosaceae family, for example, baobab trees, oak trees, beech, maple trees and other trees. Flowering plants dominate entire forest ecosystems because of their flourishing, from the lower jungle layers to the canopy vegetation.
The boom in angiosperms caused a large number of evolutionary chain reactions, especially insects. These "infantrymen" involved in the "Plant Revolution" gradually developed the ability to carry pollen between the flowers in order to return small amounts of food, thus helping flowering plants save pollen production and retain more valuable energy. In contrast, gymnosperms are mainly transmitted by wind.
Bees in particular benefit from this win-win strategy. They evolved from wasps in the Early Cretaceous, and now they are inseparable from flowers.
It is because of the rise of bees that flowers have taken a bigger, more beautiful path in order to be the first to pollinate.
A 2008 study showed that according to the Pollen Fossil Study in Minnesota, about three-quarters of angiosperms were mordants from 96 million years ago, which is almost the same as it is now. Dilchi, who led the study, says many flowers have become beautiful since then.
And so the whole world blossomed.
Even orchids, which are thought to have a later origin, caught up with the flowering trend in the Late Cretaceous. Although orchids have 22,000 species and genera and are a large family in the plant kingdom, their fossil record is minimal. In 2007, a small bee changed people's understanding of the origin of orchids. About 20.21 million to 12 million years ago, somewhere in today's Domini, a bee encountered a flower, and it also collected some pollen. Then it turned amber. The pollen is preserved like two peas, almost like the pollen of some tropical American orchids. So the researchers corrected the plant's molecular clock. They believe orchids appeared from 84 million years ago to 76 million years ago.
Another major event in the evolution of angiosperms occurred during this period: the proliferation of grasses that contributed greatly to the formation of the modern world. Rice, wheat, corn, and other crops provide us humans with the food we need to survive, while wild weeds dominate the steppe landscape. Grasslands only became popular 25 million years ago to 15 million years ago. At that time, the natural environment of the world was relatively cold and dry, but most plants adapted well to this harsh climate. Since the subsurface roots of most herbaceous plants grow vigorously, this allows them to survive in arid environments and regenerate faster after a fire or grazing.
Similarly, the history of grasses is longer than we think. Not long ago, a type of silicon was found in a dinosaur fecal fossil (seventy million years old), which is found only in grasses. It can be seen that long before the extinction of the dinosaurs, there were many species of grasses.
The species and number of angiosperms continued to increase during the Cretaceous period, and then entered the Early Tertiary Period. The "plant revolution" ended 50 million years ago when angiosperms dominated almost all habitats. It took tens of millions of years for angiosperms to grow into world-class giants.
The influence of angiosperms doesn't stop there. Our distant primate ancestors thrived in ancient flowering plant forests, and early humans gained unprecedented opportunities for evolution in the grasses of the East African savannah. In the future, humanity will benefit from the cultivation of grains, vegetables and fruits.
Angiosperms are indispensable to every step of human success. There is no doubt that the power of flowers does rule the world.