With the proliferation of blue-green algae, also called cyanobacteria, the oxygen content in the air gradually increased. It probably killed a lot of bacteria at first, but over time they...
With the proliferation of blue-green algae, also called cyanobacteria, the oxygen content in the air gradually increased. At first it probably destroyed a lot of bacteria, but over time they learned to use it for their needs. Development different types bacteria led to the emergence of other types of organisms that obtained energy simply by eating more primitive relatives. The next important stage began when more complex cells acquired the ability to photosynthesize thanks to the appearance of the chloroplast. These were the first true plant cells.
Evolution of plants
The first plants were single-celled organisms that arose when blue-green algae found shelter in large cells. These large cells already had mitochondria that came from other bacteria. In the “look” of the cells, by giving shelter to bacteria, they received a lot of benefits - mitochondria helped them use oxygen, and chloroplasts produced food for them.
These progenitors of plants obviously lived on the surface of seas and lakes, just as their numerous descendants - unicellular algae - now exist. Over time, single-celled plants developed into multicellular plants when their cells remained together after dividing. Some formed balls from cells, others - empty cylinders, chains of cells. Many organisms with such adaptations still live in the form of algae.
Path to land
For millions of years, the only form of plant life on Earth was algae. As now, they existed almost exclusively in water, because they dried out on land. Then small algae began to grow on the shores of the lakes, near the water. Over time, they developed semi-waterproof shells and root-like structures that sucked moisture from the soil.
These pioneer algae gave rise to mosses - primitive plants that can also survive only in damp places. Over time, more developed plants appeared, like ferns, with leaves covered with a waterproof shell. They were the first to develop roots and woody stems, which allowed them to grow upward.
When did the first plants appear on Earth?
Scientists believe that the first plants on Earth appeared with the beginning of the process of photosynthesis, which occurred in bacteria. This important process of interaction between liquid and sunlight became the source of the release of free oxygen. Thanks to this, the plant world was born.
First plants
People often wonder what species were the first and how they appeared on our planet. Scientists gave the answer. The first representatives of the flora to appear on earth were Rhinia and Cooksonia. The last one looked like small bush, the size of which did not exceed 5-7 cm. The most favorable conditions The swampy area was suitable for the development of Cooksonia. Traces of the presence of this cooksonia were found in the Czech Republic, the USA and Western Siberia. Rinia is a plant similar to cooksonia. Despite the similarity of origin, the size of rhinia was more significant - up to 50 cm in height. Initially, each plant had only 1 species.
According to another version, moss was one of the first to appear on earth. In addition, remains of unicellular algae and fungi were discovered. Swampy and shady areas are also considered their places of origin.
Appearance time
There is no clear answer to the question of when plants appeared on earth. Each of the representatives of the earth's flora began to appear at a certain time:
- the first unicellular organisms (mosses, lichens) - 2 billion years ago;
- more complex plants (similar to modern ferns) - 4 million years;
- conifers and pine trees appeared about 3 million years ago;
- The age of the first flowering plants is 150 million years.
Ferns are one of the first full-fledged representatives of the flora, having roots, stems and leaves. They still grow in swampy areas. By the time the planet was inhabited by dinosaurs, its surface was already inhabited by mosses, grasses, shrubs and trees. The first coniferous trees include pine, spruce, larch and cedar. Seeds of flowering representatives, compared to others, had greater protection. This explains the variety of colors.
Over time, climate change and development conditions changed, grass and trees evolved. Now too many varieties of shrubs, flowers and trees have been artificially bred. In order to visualize the plants that dominated our planet millions of years ago, you need to look at the ferns and grasses that grow in swamps and forests. They can be considered direct descendants of ancient mosses and ferns.
How did plants appear on earth? Plants are the most ancient creatures that were the first to successfully colonize the sea and land, giving impetus to the development of animals and their distribution in water and on land. It was plants that shaped the current appearance of the planet, creating an atmosphere that protects all living beings on the planet from harmful ultraviolet radiation, as well as fertile soil. There are many theories about how plants appeared and how they inhabited the planet. The first land plants did not have roots and settled at the edge of reservoirs, these first plants were cooksonia and aglophytons, which were stems with bulbs at the top, these first land plants reached only 5-6 cm in length. It was these first plants that, when they died, formed the soil near bodies of water and about 400 million years ago, roots began to appear on the plants, which allowed the plants to obtain water and nutrients from the soil. In addition, plant roots are able to penetrate the stone, destroying it, and giving the plants the opportunity to grow taller and larger.
On land, plants grew and formed the fertile soil layer and the entire ecosystem. We can give a lot of examples of how people use plants for their own purposes, but the real potential of plants is still not fully revealed. Plants colonized land because they needed sunlight, and, of course, carbon dioxide for the production of sucrose, which the plant uses for nutrition. Surprisingly, oxygen is practically a waste product of the plant's production of the sucrose it needs. As plants developed, they became more and more complex, developed leaves and strong wood, growing into huge forests of lepidodendrons, fighting for a place in the sun. Plants have always influenced the formation and development of animal species. For example, the amount of oxygen released by plants affects the size of insects, which have spiracles scattered throughout the body, saturating internal organs insects with oxygen, and if there is little oxygen, insects cannot reach large sizes.
Animals came to land precisely because of the sucrose produced by plants, and in the process of evolution a lot of animal forms arose. If you know how animals influence plants, you can understand that plants have a powerful adaptation mechanism. Plants, in the process of evolution, have acquired a lot of ways to protect their leaves from herbivores. For example, the appearance of dinosaurs - sauropods - led to the fact that plants began to acquire thorns and even began to produce toxins, for example, capsicum, so that they could not be eaten. Considering how plants adapt to life in those different conditions, it immediately becomes clear that plants are the most adapted organisms on earth. During the process of evolution, most plants became flowering plants and began to use insects as pollinators. Plants grow in all areas where there is water and light necessary for the growth and development of plants, of which there are currently about 320 species.
Vegetable world as it developed, it completely changed the appearance of the planet. The most ancient plants on the planet could survive for a long time exclusively at the water's edge, as well as in swampy areas, since in those days the land was unsuitable for life.
The oldest plants on Earth began to appear approximately 450 million years ago. Until this time, the flora was represented exclusively by algae of various types. Currently, there is no data on what exactly the first aquatic plants looked like, since their fossils have not survived to this day. Many scientists suggest that some modern aquatic plants, distinguished by their primitive structure, could resemble their ancient ancestors. In the Silurian period, in addition to the vast oceans, there was also land that was not adapted to life. The thing is that there was no soil at that time, because the entire land was covered with stones heated in the sun.
The atmosphere, which was significantly different from the modern one, did not predispose to the emergence of life, since the ozone layer at that time was insignificant and transmitted most of the ultraviolet rays. However, it was the plants of the ancient world who were the first to get to land, but only at the water's edge. There are reasons why ancient plants were able to get onto land: for many millions of years, when life already existed in the ocean, algae and the bodies of primitive animals were thrown into the coastal zone, which fertilized it.
The primary land forms of plants appeared in the Silurian period; they were extremely primitive. Rhiniophytes are considered the first ancient plants to emerge to the surface of the earth. This type of ancient plants included cooksonia, psilophyte, rinni, chlorneophyte, the structure of which has already been well studied at present. Rhiniophytes were extremely common organisms, as their fossilized remains were discovered in western Siberia, the Czech Republic, the USA, Scotland and several other parts of the world. It is believed that over a long period of time these plants began to grow among the stones that supported them. They stretched their stems upward and had bulbous shapes at the ends of the branches that produced spores.
The first plants that were able to get onto land were only 15 cm in height. They had neither roots nor leaves, but at the same time they stretched upward, which allowed them to receive the necessary amount of sunlight. Rhiniophytes were covered with a waxy film, which protected the plants from moisture loss. These plants did not have many of the organs and tissues found in modern plants. These plants reproduced by spores, which allowed them to spread throughout the coastal zone.
Over time, plant forms became more diverse. Following the bulbous forms of plants, lichens and mosses appeared. These plant forms were more adapted to life on land. These living creatures were able to secrete special substances that destroyed even strong rocks, which contributed to the formation of soil. It was lichens and mosses that prepared the surrounding areas coastline so that new, more developed forms of plants can appear on earth. These plants did not yet have true roots, but had elements resembling leaves, as well as a formed vascular system. Some modern primitive mosses and lichens have significant similarities with their distant ancestors. These plants had many features inherent higher plants. In the late Silurian period, the evolution of land plants accelerated significantly, as lycophytes and ferns began to appear.
Both of these plant species have already acquired all the organs characteristic of modern plants. Moss-shaped plants had roots and quickly grew into forests, since at that time a tropical climate had established on the planet and vast areas were occupied by swamps. There were many species of lycophytes, some of which had rigid trunks that made these plants look like modern trees, while other species were classified as climbing. These plants dominated the earth for a long time and in the Carboniferous period some varieties of lycophytes reached 46 m in height, and their trunk was approximately 1.8 m in diameter.
Fern plants shared living space with lycophytes. Ancient ferns, starting from the Devonian and Paleozoic eras, reached enormous sizes. They reached more than 30 m in length and had a huge umbrella of leaves at the top of the trunk. These plants could only thrive in swampy areas and warm climates, because they reproduced with flagellated sperm, which required water.
Until the end of the Carboniferous period different types moss and fern plants dominated the planet, producing incredible amounts of oxygen. These plants thrived for a long time until humidity levels began to decline rapidly, causing these species to have trouble reproducing. These plants were replaced by gymnosperms and flowering species.
Over many millions of years, plants have evolved, constantly undergoing changes, and adapting. Currently, there is no accurate data regarding the appearance of the oldest forms of plants, because in the hands of scientists there is not much evidence of their presence on the planet.
The first representatives of the flora appeared on the planet more than 2 billion years ago, in the era that researchers call the Archean. Let's look at the most ancient plants on Earth - what they looked like and what role they played in the evolutionary process.
Archean era
This period is separated from us by billions of years, so the data on what living organisms existed at that time are very conditional and often have the nature of hypotheses. Scientists have little material for research, since the representatives of this ancient time did not leave any traces behind them. In this geological era, there was no oxygen in the atmosphere yet, so only those organisms that did not need it could survive. Features of the plant world of the Archean era are as follows:
- The most ancient plants on Earth are considered to be blue-green algae; the fact that they already existed is evidenced by organic substances - marble, limestone.
- Colonial algae appeared later.
- The next stage in the development of flora is the appearance of photosynthetic organisms. They absorbed carbon dioxide from the atmosphere and released oxygen.
We can conclude that algae are the most ancient plants on Earth; their role was more than significant: it was these tiny representatives of the flora that managed to fill the atmosphere with the oxygen necessary for life and made it possible for further evolution. Living organisms were able to leave the sea and move to land.
Proterozoic
The next stage in the development of the most ancient plants on Earth is the Proterozoic era, it was then that many varieties of algae originated:
- red;
- brown;
- green.
It was during this era that a clear division of organisms into plants and animals occurred. The former could synthesize oxygen, but the latter did not have this ability.
Paleozoic
The most ancient plants on Earth are seaweed, and it is to them that we owe the appearance of an oxygen-rich atmosphere. They made our world habitable. In the first two periods of the Paleozoic, the flora was represented exclusively by algae, but other plants gradually appeared:
- During the Silurian period, spore plants formed. Soil appeared, so they were able to grow on land.
- Rhyniophytes, the simplest representatives of the fauna, arose in Delur.
- Next, mosses and primordial ferns and gymnosperms appear.
- During the Carboniferous period, horsetail-like ferns appear.
The first forests of huge horsetails, ferns and mosses appear on the planet. During the Carboniferous period, club mosses and calamites reached their peak, often rising 30-40 meters above the surface of the earth. Gradually dying off, these plants formed reserves of coal, which humanity uses to this day. The most ancient plants on Earth played a vital role in giving us valuable minerals. Without coal, industrial development would be impossible.
During the Permian period, some coniferous species are formed.
Plants coming to land: features of the process
The most ancient plants on Earth that left the water element and moved to land, as researchers believe, were algae and lichens. They did not leave behind any traces and conclusions about their existence are made only based on indirect signs:
- Rock formation. This process is possible only with the participation of living organisms.
- The process of soil formation could not take place in water - this indicates that the plants had already reached the surface of the earth.
- Nowadays, fossil-like algae are found on land as plaque on rocks and tree bark, under conditions of increased importance. Therefore, researchers suggest that in ancient periods they could also adapt to life outside the sea.
In later periods of the Paleozoic, land plants, which have not survived to this day. Only their petrified spores have survived. They are very similar to the spores of liverworts, modern plants related to mosses. We can conclude that the most ancient plants on Earth are mosses, while horsetails “emerged” from the sea and settled on land during the late Paleozoic period.
First forests
The first representatives of the flora preferred to settle in damp places, so fern forests were often drowned in water. The most ancient forests were shallow bodies of water, similar to swamps, but lacking a peat layer. It was here that giant ferns grew. Such an ecosystem is often called a forest-reservoir.
First gymnosperms
The most ancient plants on Earth reproduced by spores, which were very vulnerable and could die in unfavorable environmental conditions. Therefore, the appearance of gymnosperms was the most important step on the path of evolution. The seeds had a number of advantages over disputes:
- they had a supply of nutrients;
- could survive adverse conditions;
- were not afraid of exposure to UV rays and drying out;
Mesozoic
At this time, the most important processes occur:
- formation of continents;
- the birth of lakes and seas;
- climate change.
The flora is also undergoing significant changes: giant ferns and club mosses are dying out, and gymnosperm coniferous trees are becoming widespread. Imprints of plants with characteristics characteristic of angiosperms were discovered in layers of the Early Cretaceous and Jurassic periods. These were primitive and few in number. Angiosperms became widespread in the Middle Cretaceous, about one hundred million years ago. However, by the end of the period they became the dominant form of plant life on Earth. The plant world became more and more similar to what we are used to.
Features of the flora of the Mesozoic era are as follows:
- The appearance of vessels in plants, the functions of which were to conduct water and nutrients.
- A reproductive organ is formed - a flower. Thanks to insect pollination flowering plants quickly spread across the continents.
- The predecessors of modern cypresses and pines appear.
We looked at which plants are the most ancient on Earth, and traced the main paths of the evolutionary development of flora across geological eras. Despite the fact that the first algae did not leave any traces behind, their role was enormous: they were able to fill the planet’s atmosphere with oxygen and made possible exit living organisms on land.
Looking at my home cactus, I couldn’t help but think: “How did plants even begin their journey on land? And when did this happen?” About this very interesting topic I would like to tell you.
How and when did the first sushi plants appear?
As is known, all earthly life originated in water. And plants are no exception. Once upon a time they were all protozoan algae, but then a stage came when they began to germinate on land.
And they began their emergence to the surface at the end Silura (near 4 05-440 million years ago), what in Paleozoic era. Then powerful events were actively taking place mining processes, leading to shallowing and drying up of many seas. This is what caused some algae to “come out” onto land.
The very first plants on the surface are psilophytes. They had only a bare stem, which was attached to the ground with the help of special outgrowths - rhizoids. The psilophytes themselves had a very simple structure, but they had branching stems with outgrowths that stored disputes.
Psilophytes preferred marshy and wet area, because they did not have a powerful root system to extract water. Today it is believed that such plants once lined endless carpets on the bare surface of the Earth.
In addition, psilophytes could be like very high(much larger than human height), and very low and tiny.
How did the first land plants adapt?
Worth a special mention fixture system, which plants have mastered for life on land. After all, they are very different from life under water. So, these difficulties could be called:
- necessity water conservation from its evaporation in air;
- need for education hard protective cover;
- adaptation to constantly changing conditions environment.
And many others. Such plants also needed to learn to carry out more complex photosynthesis, anchor in the soil and get from it the necessary minerals.
All these difficulties were overcome by plant organisms. And the evidence of this is our life on Earth.
