The main stages of the development of the plant world - Hypermarket of knowledge. Stages of evolution of the plant world Change and development of the plant world

Cyanobacteria, since their cells lack formed nuclei. Thus, they can be classified as prokaryotes (prenuclear organisms). Among the blue-green algae there were single- and multicellular organisms that had the ability to carry out photosynthesis. Thanks to the process of photosynthesis, oxygen, necessary for the life of aerobes, began to enter the atmosphere of our planet.

Later in the Proterozoic era (about 2600 million years ago), red and green algae took over the Earth. Their dominance extended into the Paleozoic era (approximately 570 million years ago). Only in the late Paleozoic (Silurian period) was the vital activity on the planet of the most ancient higher plants - rhinophytes, or psilophytes - noted. These plants had shoots, but no roots or leaves. Rhinophytes reproduced by spores. They lived on land or partially in water. In the existence of our planet, a new era began with the appearance of higher, or land plants. About 400-360 million years ago, in the Devonian period of the Paleozoic era, against the background of the predominance of rhiniophytes and algae on Earth, the first pteridophytes (ferns, horsetails, mosses) and moss-like plants appeared. They belong to higher spore plants. Thanks to the spread of plants on land, new terrestrial animal species appeared. The combined changes in the evolution of plant and animal forms have led to the enormous diversity of life on Earth. The face of the planet has changed radically. The attached way of life of the plant on land led to the appearance of division of the plant into roots, stems and leaves, as well as to the emergence of supporting tissues and a vascular conduction system. The very first land plants were small. They absorbed water through rhizoids, like mosses that have survived to this day on Earth. The haploid generation (gametophyte) predominated in their development cycle. Gradually, larger forms of plants appeared - fern-like ones, in which complex specialized organs were formed - roots with root hairs. In the development cycle of these plants, the diploid phase comes to the fore - the sporophyte, which is the plant itself, while the gametophyte is a shoot that looks like a nodule in horsetails and mosses and like a small heart-shaped plate in ferns. This is how a gradual transition was carried out from the haploid generation to a more perfect one - the diploid one. In the Paleozoic era, ferns were huge plants that dominated the land. However, for their reproduction, water was necessary, which limited the territory of their existence to areas with high humidity.

In the Carboniferous period, which lasted from 360 to 280 million years ago, the appearance of seed ferns on our planet, which later became the ancestors of all gymnosperms, was proven. At this time, rhinophytes completely disappear due to the inability to compete with more developed plants. And the huge tree-like ferns that were dominant at that time, after dying off, formed deposits of coal.

In the next Permian period of the Paleozoic era, ancient gymnosperms appeared on Earth. Tree ferns are gradually dying out, and they are being replaced by seed and herbaceous ferns, taking over the land. Holo feature seed plants is that their reproduction is carried out by seeds that do not have protection in the form of fruit walls, since these plants do not form flowers and fruits. Sexual reproduction of these plants was carried out independently of drip- aquatic environment. And their appearance during evolutionary metamorphoses was due to changes in humidity and temperature and changes in the Earth’s topography due to the rise of land, that is, the appearance of mountain ranges.

The Mesozoic era began about 240 million years ago. In the Triassic period of the Mesozoic, modern gymnosperms appeared, and in Jurassic period The first angiosperms originated. But the dominant position on the planet remained with gymnosperms. This is the era of extinction of ancient ferns that could not withstand natural selection. During the emergence of angiosperms, a series of aromorphoses occurred. First, a flower was formed - a transformed shoot adapted for the formation of spores and gametes. Pollination, fertilization and the formation of the embryo and fruit occurred directly in the flower. Secondly, for better protection and propagation, the seeds of angiosperms were surrounded by a pericarp. These plants are characterized by sexual reproduction. Angiosperms include herbaceous plants, trees and shrubs. Various modifications of vegetative organs (root, stem, leaf) are observed in different types plants. Evolutionary changes in angiosperms occurred over a relatively short term Therefore, they are characterized by high evolutionary plasticity. Insect pollinators played a huge role in the course of evolutionary transformations. Angiosperms more productively develop the environment and conquer new territories, thanks to their structural features and ability to form complex multi-layered communities.

In the Cenozoic era, which began approximately 70 million years ago, existing angiosperms and gymnosperms began to dominate our planet, while higher spore plants regressed.

Nowadays, more than 350 species of plants grow on Earth, among them are flowering plants, bryophytes, ferns, and algae.

Planet Earth was formed more than 4.5 billion years ago. The first single-celled life forms appeared perhaps about 3 billion years ago. At first it was bacteria. They are classified as prokaryotes because they do not have a cell nucleus. Eukaryotic (those with nuclei in cells) organisms appeared later.

Plants are eukaryotes capable of photosynthesis. In the process of evolution, photosynthesis appeared earlier than eukaryotes. At that time it existed in some bacteria. These were blue-green bacteria (cyanobacteria). Some of them have survived to this day.

According to the most common hypothesis of evolution, plant cell formed by the entry into a heterotrophic eukaryotic cell of a photosynthetic bacterium that was not digested. Further, the process of evolution led to the appearance of a single-celled eukaryotic photosynthetic organism with chloroplasts (their predecessors). This is how unicellular algae appeared.

The next stage in the evolution of plants was the emergence of multicellular algae. They reached great diversity and lived exclusively in water.

The surface of the Earth did not remain unchanged. Where the earth's crust rose, land gradually emerged. Living organisms had to adapt to new conditions. Some ancient algae were gradually able to adapt to a terrestrial lifestyle. In the process of evolution, their structure became more complex, tissues appeared, primarily integumentary and conductive.

The first land plants are considered to be psilophytes, which appeared about 400 million years ago. They have not survived to this day.

Further evolution of plants, associated with the complication of their structure, took place on land.

During the time of the psilophytes, the climate was warm and humid. Psilophytes grew near bodies of water. They had rhizoids (like roots), with which they anchored themselves in the soil and absorbed water. However, they did not have true vegetative organs (roots, stems and leaves). Promotion of water and organic matter the plant was provided by the emerging conductive tissue.

Later, ferns and mosses evolved from psilophytes. These plants have more complex structure, they have stems and leaves, they are better adapted to living on land. However, just like psilophytes, they remained dependent on water. During sexual reproduction, in order for the sperm to reach the egg, they need water. Therefore, “go away” far from wet places they could not live.

In the Carboniferous period (about 300 million years ago), when the climate was humid, ferns reached their dawn, and many of them grew on the planet. wood forms. Later, dying off, it was they who formed coal deposits.

When the climate on Earth began to become colder and drier, ferns began to die out en masse. But some of their species before this gave rise to the so-called seed ferns, which in fact were already gymnosperms. In the subsequent evolution of plants, seed ferns became extinct, giving rise to other gymnosperms. Later, more advanced gymnosperms appeared - conifers.

The reproduction of gymnosperms no longer depended on the presence of liquid water. Pollination occurred with the help of wind. Instead of sperm (mobile forms), they formed sperm (immobile forms), which were delivered to the egg special education pollen grain. In addition, gymnosperms produced not spores, but seeds containing a reserve nutrients.

The further evolution of plants was marked by the appearance of angiosperms (flowering plants). This happened about 130 million years ago. And about 60 million years ago they began to dominate the Earth. Compared to gymnosperms, flowering plants better adapted for life on land. You could say they began to take advantage of opportunities more environment. So their pollination began to occur not only with the help of the wind, but also with the help of insects. This increased pollination efficiency. Angiosperm seeds are found in fruits, which allow them to spread more efficiently. In addition, flowering plants have a more complex tissue structure, for example, in the conducting system.

Currently, angiosperms are the most numerous group of plants in terms of the number of species.

The first plant organisms arose in the wild in very distant times. The first living beings were microscopically small lumps of mucus. Much later, some of them developed a green color, and these living organisms began to look like unicellular algae. Single-celled creatures gave rise to multicellular organisms, which, like single-celled organisms, arose in water. From unicellular algae, various multicellular algae developed.

The surface of the continents and the ocean floor have changed over time. New continents rose and previously existing ones sank. Due to hesitation earth's crust In place of the seas, land arose. The study of fossil remains shows that the plant world of the Earth also gradually changed.

The transition of plants to a terrestrial lifestyle, according to scientists, was associated with the existence of land areas that were periodically flooded and cleared of water. The receding water was retained in the depressions. They either dried up or filled with water again. The drainage of these areas occurred gradually. Some algae have developed adaptations for living outside of water.

The climate at that time was globe was humid and warm. The transition of some plants from an aquatic to a terrestrial lifestyle began. The structure of these plants gradually became more complex. They gave rise to the first land plants. The oldest group of known land plants are psilophytes.

Development flora on Earth - a long-term process, which is based on the transition of plants from an aquatic to a terrestrial way of life.

Psilophytes already existed 420-400 million years ago, and later became extinct. Psilophytes grew along the banks of reservoirs and were small multicellular green plants. They had no roots, stems, or leaves. The role of roots was played by rhizoids. Psilophytes, unlike algae, have a more complex internal structure- presence of integumentary and conductive tissues. They reproduced by spores.

From psilophytes came bryophytes and ferns, which already had stems, leaves and roots. The heyday of ferns was about 300 million years ago during the Carboniferous period. The climate at this time was warm and humid. At the end of the Carboniferous period, the Earth's climate became noticeably drier and colder. Tree ferns, horsetails and club mosses began to die out, but by this time primitive gymnosperms appeared - descendants of some ancient ferns. According to scientists, the first gymnosperms were seed ferns, which later became completely extinct. Their seeds developed on the leaves: these plants did not have cones. Seed ferns were tree-like, liana-like and herbaceous plants. Gymnosperms originated from them.

Living conditions continued to change. Where the climate was more severe, ancient gymnosperms gradually died out and were replaced by more advanced plants - ancient conifers, then they were replaced by modern conifers: pine, spruce, larch, etc.

The transition of plants to land is closely connected not only with the appearance of organs such as stems, leaves, and roots, but, mainly, with the appearance of seeds, a special method of reproduction of these plants. Plants that reproduced by seeds were better adapted to life on land than plants that reproduced by spores. This became especially clear when the climate became less humid.

On the growths developing from spores (in mosses, mosses, ferns), female and male gametes (sex cells) are formed - eggs and sperm. In order for fertilization to occur (after the fusion of gametes), atmospheric or groundwater, in which sperm move towards eggs.

Gymnosperms do not need free water for fertilization, since it occurs inside the ovules. In them, male gametes (sperm) approach female gametes (eggs) through pollen tubes growing inside the ovules. Thus, fertilization in spore plants is completely dependent on the availability of water; in plants that reproduce by seeds, this dependence is not present.

Angiosperms - descendants of ancient gymnosperms - appeared on Earth over 130-120 million years ago. They turned out to be the most adapted to life on land, since only they have special reproductive organs - flowers, and their seeds develop inside the fruit and are well protected by the pericarp.

Thanks to this, angiosperms quickly spread throughout the Earth and occupied a wide variety of habitats. For more than 60 million years, angiosperms have dominated the Earth. In Fig. 67 shows not only the sequence of appearance of certain plant divisions, but also their quantitative composition, where angiosperms have a significant place.

Hello, friends! Today I would like to talk about prehistoric plants and how they evolved into modern plants.

The plant world today is dominated by flowering plants, but club mosses and ferns covered the Earth in prehistoric times.

More than 400,000 species of flora are known today, all descended from a few ancient marine plants. Species that have disappeared from the face of the Earth are not included in this number, since they were unable to adapt to changing conditions on Earth, or could not withstand competition from newly appeared plants that were better adapted to new environment a habitat.

Paleobotanists have established the distribution of plant cover on the Earth's surface at different times. geological periods, as well as the patterns of its change. The fact that plants do not have a hard skeleton that can easily be turned into fossils makes research difficult.

Fortunately, early forms of flora can sometimes be found in ancient mud deposits, and in rocks Some plant remains were found, their age is about 3.1 billion years.

The fact that life on the planet had to begin with the appearance of plant-like organisms, which became an important link in the food chain animals later, fossils show.

But the role of plants in evolutionary history Earth, since they actually transformed our planet and made it suitable for the existence of the animal world.

Probably, under the initial conditions of a huge amount of carbon dioxide in the atmosphere, animals would not be able to breathe. Plants convert carbon dioxide into oxygen through the process of photosynthesis, saturating the atmosphere with it.

The basis of the food chain was the ability of plants to use sunlight to produce complex organic substances. The evolution of carnivores and herbivores was ensured by plants.

Evolution, however, is an extremely slow process, and natural selection favors individuals that adapt to changes in their environment rather than simply to change itself.

The most ancient species of the plant world could not survive without water, since they did not have the structures necessary for life on land.

The first plants to emerge from the water probably settled in swamps, where they Bottom part could constantly be under water. Most likely, the first truly terrestrial plants remained moisture-loving and grew near water.

A moist environment for reproduction was still necessary for liverworts, mosses and ferns, which developed as plants from ancient times.

Precursors of flowering plants – gymnosperms, among them coniferous trees- needed wind for seed dispersal and pollination, since there were no insects capable of doing this at that time.

The flowering plants (angiosperms) that predominate today developed at the same time as insects and animals, and are therefore often pollinated by them.

The simplest algae were the oldest known plants.

These are single-celled organisms, all the functions of which were performed by a single cell without a nucleus. These blue-green algae were extremely primitive, and only about 1.5 billion years ago they appeared with a cell nucleus.

Multicellular organisms arose over time. Perhaps they are similar to seaweed and have different parts plants are reproductive organs.

About 590 million years ago, during the Cambrian period, many forms of life firmly established themselves on Earth. More than 900 species belong to this period - and these are the plants that have survived and been discovered hundreds of millions of years later.

Relocation to land.

440 - 408 million years ago, during the Silurian period, plants emerged from the water and began to populate the land. The habitat of plants and animals in ancient times was limited to the oceans, but to life in fresh water algae have adapted. Terrestrial species probably evolved from these freshwater algae.

They must have a completely different structure aquatic plants to survive on land. They must contain a more rigid plant-supporting organ, as well as a network of blood vessels.

A reproductive system that is capable of functioning normally in air environment, must establish land plants before moving to drier areas.

Traces of the most ancient plants were discovered in the rocks of the Silurian period. The body of one of them, Zosterophyllum, was a thallus, that is, it was not divided into stem, root and leaves. Rhynia is a plant without leaves and roots, but with large sporangia at the ends of its shoots.

It consisted of a functioning root, rhizome and above-ground shoots dotted with small scale-like leaves. It is very likely that they were all swamp plants.

Roots that accumulate and absorb water appeared in plants for growing on land. Their methods of reproduction, which are less dependent on moisture, have been improved in the course of very long period evolution.

Unlike flowering plants that appeared later, relict species that survive to this day, such as liverworts and mosses, still require a moist environment and water to reproduce.

Evolutionary progress.

The process of evolution does not have to be linear or continuous with a constant pace of development.

The following groups of plants almost certainly arose during evolution, and in the given order. The fact that evolution is an ongoing and now continuous process should not be forgotten. It is only after a very long period of time that changes can be detected.

Bacteria.

It is likely that the first cellular organisms lived in the “primary” broth and resembled. It is generally accepted that bacteria are closer to plants than to animals, although they have little in common with either. These microscopic single-celled organisms are capable of multiplying with amazing speed under ideal conditions.

However, some of them can live in organic substances, such as nitrogen and ammonia, which may be due to their appearance in ancient times, when a large number of ammonia was contained in the Earth's atmosphere.

Blue-green algae.

Despite their name, these primitive plants bear little resemblance to real algae. 3.1 billion years old, isolated fossils found in rocks closely resemble modern blue-green algae.

This proves that they belong to those capable of photosynthesis, the oldest species. Microscopic unicellular non-nuclear organisms - This is the majority of blue-green algae.

But due to the fact that the mucus of some algae contains entire colonies of these plants, some of them can be seen with the naked eye.

Seaweed.

This is another type of primitive plant that lacks flowering structures and leaves. Obtain food through photosynthesis under the influence of natural sunlight Almost all types of algae are capable.

The predominance of such primitive plants includes plankton, mainly consisting of unicellular algae, and multicellular algae.

Freshwater and terrestrial algae have spread widely. To the “blooming” of water in reservoirs and plaque formed on the walls of aquariums, wet clay pots It is they who bring other vessels.

Algae are multicellular and unicellular and can form colonies or threads. Some of their species are considered to be the connecting link between animals and plants.

Euglenophytes are capable of locomotion using flagella, have a light-sensitive red ocellus, and can ingest solid food particles.

Lichens.

The result of mutualism between fungi and algae are such complex plants. Only after these two were formed independent species plants, lichens were able to appear.

From the point of view of evolution, they have occupied a free niche and are able to exist in unfavorable conditions, in which few other plants can survive.

Mosses and liverworts.

Although the evolution of mosses and liverworts is still ongoing, they are similar to primitive plants. They have clearly defined stems and leaf-like structures, as well as signs of the beginning of the development of vascular conducting tissue. Mosses and liverworts reproduce by spores, and there are two stages of reproduction.

First, the sporophyte (the dominant form bearing spores) appears, and then the gametophyte (sexual generation).

Alternating generation – the name of this complex process. It requires a very moist environment or water. This is another property that confirms ancient origins mosses and liverworts and preventing their spread over land.

Ferns and horsetails.

These plants more often reproduce by spores than by seeds, but they are also characterized by alternating generations. Therefore, they require water or a high moisture content to reproduce successfully.

Sporophytes are less dependent on moisture. Although the spore generation must grow close to moist areas for gametophyte development, this means that the habitat of ferns is more diverse than that of mosses and liverworts.

The more complex structure of ferns indicates a later evolution. However, it is known that in the Devonian (480 - 360 million years ago) they were widespread. This structure allows ferns to adapt to life on land and gives them the rigidity necessary for further growth.

Moss mosses and horsetails are related to ferns, but are much less common than ferns. During the Carboniferous period (360 million years ago), horsetails dominated. And from their fossilized remains most of the coal was formed. Then, they were gradually replaced by other species.

Pteridosperms.

The ancestors of modern flowering plants were pteridosperms or seed ferns. Now it is an extinct species. Externally, pteridosperms looked like ferns, but they formed seeds at the ends of special shoots. They lived in the period from the Devonian to the Triassic (248 million years ago).

Gymnosperms.

Almost only trees include gymnosperms. Their evolutionary process began later than that of the groups listed above. They appeared in the Mesozoic era. They have ovules and cones, which, unlike angiosperms, lack carpels.

Coniferous trees such as larch and pine are the most famous gymnosperms. And tropical species– ginkgo and cycads. In the Mesozoic era, cycads became most widespread.

Also a coniferous tree is the giant sequoia, which can reach very large sizes. Huge economic importance have coniferous trees. They are grown in large quantities for timber and pulp production.

Angiosperms.

IN modern world this is the predominant group of plants. It includes both flowers (daisy and dandelion) and trees (for example, horse chestnut, oak). Angiosperms include most of the vegetables we consume, orchids, ornamental grasses, with which lawns are sown, as well as various cereals (including oats and wheat).

Angiosperms- These are flowering plants. Their seeds are enclosed in carpels. The evolution of these plants took different paths. Both insects and wind play important roles in the pollination of these plants. Certain types Some of them are pollinated by insects or birds. The methods of dispersing seeds are also very diverse.

This is the evolution of plants, it turns out that it is a rather complex process 🙂

Table covering the evolution of plants by geological periods

1. What plants are classified as lower? What is their difference from the higher ones?
2. Which group of plants currently dominates our planet?

Methods for studying ancient plants. World modern plants diverse (Fig. 83). But in the past, the plant world of the Earth was completely different. Paleontology helps us trace the picture of the historical development of life from its beginning to the present day (from the Greek words “palaios” - ancient, “he/ontos” - existing and “logos”) - the science of extinct organisms, their change in time and space .

Rice. 83. Approximate number of species of modern plants

One of the branches of paleontology - paleobotany - studies the fossil remains of ancient plants preserved in layers of geological sediments. It has been proven that over the centuries the species composition of plant communities has changed. Many plant species died out, others came to replace them. Sometimes plants found themselves in such conditions (in a swamp, under a layer of collapsed rock) that without access to oxygen they did not rot, but were saturated with minerals. Petrification occurred. Petrified trees are often found in coal mines. They are so well preserved that their internal structure can be studied. Sometimes imprints remain on hard rocks, by which one can judge appearance ancient fossil organisms (Fig. 84). Spores and pollen found in sedimentary rocks can tell scientists a lot. Using special methods, it is possible to determine the age of fossil plants and their species composition.

Rice. 84. Imprints of ancient plants

Change and development of the plant world. Fossil remains of plants indicate that in ancient times the plant world of our planet was completely different from what it is now.

In the most ancient layers of the earth's crust, it is not possible to find signs of living organisms. In later sediments, remains of primitive organisms are found. The younger the layer, the more often more complex organisms are found, which become increasingly similar to modern ones.

Many millions of years ago there was no life on Earth. Then the first primitive organisms appeared, which gradually changed and transformed, giving way to new, more complex ones.

In progress long-term development many plants on Earth have disappeared without a trace, others have changed beyond recognition. Therefore, it is very difficult to completely restore the history of the development of the plant world. But scientists have already proven that everything modern views plants evolved from more ancient forms.

Initial stages of development of the plant world. The study of the oldest layers of the earth's crust, imprints and fossils of previously living plants and animals, and many other studies have made it possible to establish that the Earth was formed more than 5 billion years ago.

The first living organisms appeared in water approximately 3.5-4 billion years ago. The simplest single-celled organisms were similar in structure to bacteria. They did not yet have a separate nucleus, but they had a metabolic system and the ability to reproduce. They used organic and mineral substances dissolved in the water of the primary ocean for food. Gradually, the supply of nutrients in the primary ocean began to deplete. A fight for food began between the cells. Under these conditions, some cells developed a green pigment - chlorophyll, and they adapted to use the energy of sunlight to convert water and food into food. carbon dioxide. This is how photosynthesis arose, that is, the process of formation of organic substances from inorganic ones using light energy. With the advent of photosynthesis, oxygen began to accumulate in the atmosphere. The composition of the air began to gradually approach the modern one, that is, it mainly includes nitrogen, oxygen and a small amount of carbon dioxide. This atmosphere contributed to the development of more advanced forms of life.

The appearance of algae. Single-celled algae evolved from the ancient simplest unicellular organisms capable of photosynthesis. Single-celled algae are the ancestors of the plant kingdom. Along with floating forms, those attached to the bottom also appeared among the algae. This way of life led to the division of the body into parts: some of them serve for attachment to the substrate, others carry out photosynthesis. In some green algae, this was achieved thanks to a giant multinucleate cell, divided into leaf-like and root-like parts. However, the division of the multicellular body into parts that perform different functions turned out to be more promising.

The occurrence of sexual reproduction in algae was important for the further development of plants. Sexual reproduction contributed to the variability of organisms and their acquisition of new properties that helped them adapt to new living conditions.

Plants coming to land. The surface of continents and the ocean floor have changed over time. New continents rose and existing ones sank. Due to vibrations of the earth's crust, land appeared in place of the seas. The study of fossil remains shows that the plant world of the Earth also changed.

The transition of plants to a terrestrial lifestyle was apparently associated with the existence of land areas that were periodically flooded and cleared of water. The drainage of these areas occurred gradually. Some algae began to develop adaptations for living outside of water.

At this time, the globe had a humid and warm climate. The transition of some plants from an aquatic to a terrestrial lifestyle began. The structure of ancient multicellular algae gradually became more complex, and they gave rise to the first land plants (Fig. 85).

Rice. 85. The first sushi plants

One of the first land plants were rhiniophytes that grew along the banks of reservoirs, for example rhinia (Fig. 86). They existed 420-400 million years ago and then died out.

Figure 86. Rhiniophytes

The structure of rhinophytes still resembled the structure of multicellular algae: there were no real stems, leaves, roots, they reached a height of about 25 cm. The rhizoids, with the help of which they attached to the soil, absorbed water and mineral salts from it. Along with the similarity of roots, stems and primitive conducting systems, rhiniophytes had integumentary tissue that protected them from drying out. They reproduced by spores.

Origin of higher spore plants. From rhiniophyte-like plants came the ancient mosses, horsetails and ferns and, apparently, mosses, which already had stems, leaves, and roots (Fig. 87). These were typical spore plants; they reached their heyday about 300 million years ago, when the climate was warm and humid, which favored the growth and reproduction of ferns, horsetails and mosses. However, their emergence onto land and separation from the aquatic environment was not yet final. During sexual reproduction, spore plants require an aquatic environment for fertilization.

Rice. 87. Origin of higher plants

Development of seed plants. At the end of the Carboniferous period, the Earth's climate almost everywhere became drier and colder. Tree ferns, horsetails and mosses gradually died out. Primitive gymnosperms appeared - descendants of some ancient fern-like plants.

Living conditions continued to change. Where the climate became more severe, ancient gymnosperms gradually died out (Fig. 88). They were replaced by more advanced plants - pine, spruce, fir.

Plants that reproduced by seeds were better adapted to life on land than plants that reproduced by spores. This is due to the fact that the possibility of fertilization in them does not depend on the availability of water in external environment. The superiority of seed plants over spore plants became especially clear when the climate became less humid.

Angiosperms appeared on Earth about 130 million years ago.

Angiosperms turned out to be the most adapted plants for life on land. Only angiosperms have flowers; their seeds develop inside the fruit and are protected by the pericarp. Angiosperms quickly spread throughout the Earth and occupied all possible habitats. For more than 60 million years, angiosperms have dominated the Earth.

Adapted to different conditions existence, angiosperms created a diverse plant cover of the Earth from trees, shrubs and grasses.

New concepts

Paleontology. Paleobotany. Rhiniophytes

Questions

1. Based on what data can we say that the plant world developed and became more complex gradually?
2. Where did the first living organisms appear?
3. What was the significance of the advent of photosynthesis?
4. Under the influence of what conditions did ancient plants switch from an aquatic lifestyle to a terrestrial one?
5. Which ancient plants gave rise to ferns, and which to gymnosperms?
6. What is the advantage of seed plants over spore plants?
7. Compare gymnosperms and angiosperms. What structural features provided an advantage to angiosperms?

Quests for the curious

In summer, explore the steep banks of rivers, the slopes of deep ravines, quarries, pieces of coal, and limestone. Find fossilized ancient organisms or their imprints.

Sketch them. Try to determine which ancient organisms they belong to.

Do you know that...

Most ancient imprint The flowers of the plant were found in Colorado (USA) in 1953. The plant looked like a palm tree. The imprint is 65 million years old.

Some forms of ancient angiosperms: poplars, oaks, willows, eucalyptus, palm trees - have survived to this day.

The Plant Kingdom is surprisingly diverse. It includes algae, mosses, mosses, horsetails, ferns, gymnosperms and angiosperms (flowering) plants.

Lower plants - algae - have a relatively simple structure. They can be unicellular or multicellular, but their body (thallus) is not divided into organs. There are green, brown and red algae. They produce huge amounts of oxygen, which not only dissolves in water, but is also released into the atmosphere.

Man uses seaweed in the chemical industry. From them we obtain iodine, potassium salts, cellulose, alcohol, acetic acid and other products. In many countries, seaweed is used to prepare a variety of dishes. They are very useful, as they contain a lot of carbohydrates, vitamins, and are rich in iodine.

Lichens consist of two organisms - a fungus and an algae, which are in a complex interaction. Lichens play an important role in nature, being the first to settle in the most barren places. When they die, they form soil on which other plants can live.

Higher plants are called mosses, mosses, horsetails, ferns, gymnosperms and angiosperms. Their body is divided into organs, each of which performs specific functions.

Mosses, mosses, horsetails, and ferns reproduce by spores. They are classified as higher spore plants. Gymnosperms and angiosperms are higher seed plants.

Angiosperms have the most high organization. They are widespread in nature and are the dominant group of plants on our planet.

Almost all agricultural plants grown by humans are angiosperms. They provide people with food, raw materials for various industries, and are used in medicine.

The study of fossil remains proves historical development flora for many millions of years. The first to appear from plants were algae, which evolved from more simple organisms. They lived in the water of the seas and oceans. Ancient algae gave rise to the first land plants - rhiniophytes, from which came mosses, horsetails, mosses and ferns. Ferns reached their heyday in the Carboniferous period. With climate change, they were replaced first by gymnosperms and then by angiosperms. Angiosperms are the most numerous and highly organized group of plants. It has become dominant on Earth.