In appearance, in their structure and biological characteristics, higher plants are very diverse. These, in addition to flowering and gymnosperms, also include ferns, horsetails, mosses and mosses. The main difference between gymnosperms and higher spore plants is seed reproduction. The number of species reaches 300 thousand, and, according to some botanists, at least 500 thousand.
General characteristics
Higher plants have developed many different adaptations and properties for living in a variety of land conditions. Angiosperms have achieved the greatest development and adaptability to a terrestrial lifestyle.
Characteristics characteristic of higher plants:
- Differentiation into organs and tissues;
- conducting system consisting of xylem and phloem;
- correct change of generations;
- organs of sexual reproduction: antheridia and archegonia;
- The plant body is characterized by a leaf-stem structure.
Grounds for dividing plants into higher and lower
All representatives of the plant world, depending on their structure, are divided into 2 groups - lower and higher.
The main criterion by which plants are classified as higher is the presence of a complex tissue structure. It is represented by conductive and mechanical tissues. Also a distinctive feature is the presence of tracheas, tracheids and sieve tubes, which quickly deliver nutrients from the root to the leaves, inflorescences, and stems.
The lower ones, in turn, have a primitive structure, consisting of one cell; there are multicellular organisms, the body of which is called a thallus. They are devoid of roots, stems, and leaves.
Lack of muscle and nerve tissue
Higher plants are a group of living organisms that occupy a special place in nature. Representatives of the plant world are capable of photosynthesis; they convert the energy of sunlight into organic substances and oxygen. They get their nutrition from the soil and their environment, so they do not need to move around in search of food. Fertilization is carried out with the help of rodents, insects, and wind, so their muscle and nervous tissue is not developed. Unlike animals that travel vast distances to obtain food and search for favorable places to breed and raise offspring.
Meaning in nature and human life
- Enrichment of atmospheric air with oxygen.
- An integral link in food chains.
- Used as a building material, raw material for making paper, furniture, etc.
- Application of beneficial properties in medicine.
- Production of natural fabrics (linen, cotton).
- Cleans the air from dust pollutants.
Life cycle
Higher plants are characterized by the presence of a clearly expressed alternation of two generations: sexual (gametophyte) and asexual (sporophyte). The sporophyte gradually took a dominant position over the gametophyte. Only bryophytes are an exception, since in them the gametophyte reaches greater development, and the sporophyte, on the contrary, is significantly reduced.
In the process of evolution, the sexual process has become more complex, multicellular reproductive organs have developed, which well protect the egg from drying out. The female gamete - the egg - is immobile. Gradually, significant changes occurred in the structure and physiology of male germ cells.
In more advanced types of higher plants (angiosperms), motile sperm with flagella turned into sperm without flagella, which lost the ability to move independently. And if in more ancient terrestrial representatives (mosses, mosses, horsetails and ferns) there is still a dependence of the act of fertilization on the aquatic environment, then in more organized types (most gymnosperms and all angiosperms) complete independence of sexual reproduction from drop-liquid water is observed.
Sporophyte is an asexual diploid generation on which organs of asexual reproduction - sporangia - are formed. After reduction division, haploid spores are formed in them. From them a haploid gametophyte develops.
Origin
About 400 million years ago, the first forms of plants adapted to life on land appeared. The exit from the water led to adaptive changes in the structure of certain species, which needed new structural elements to survive.
So the plant world left the aquatic environment and began to populate the expanses of land. Such “pathfinders” were rhinophytes that grew near the shores of reservoirs.
This is a transitional form of life between lower plants (algae) and higher ones. The structure of rhinophytes has many similarities with algae: true stems, leaves, and root systems were not visible. They were attached to the soil using rhizoids, through which they received nutrients and water. Rhinophytes had integumentary tissues that protected them from drying out. They reproduced using spores.
Rhiniophytes subsequently modified and gave rise to the development of club mosses, horsetails, and ferns, which already had stems, leaves, and roots. These were the ancestors of modern spore plants.
Why are mosses and flowering plants classified as higher spores?
Mosses are higher plants that have the most primitive structure. There is no root system. They are distinguished from algae by the presence of rhizoids; the body is differentiated into organs and tissues. Mosses, like higher plants, reproduce by spores.
Flowering representatives have a body divided into organs. Vegetative organs are roots and shoots that ensure growth and development. As well as reproductive organs - fruit, seeds, flowers, which are responsible for propagation.
Similarities and differences with algae
Differences:
- Algae are not differentiated into organs and tissues; often the body is represented by one cell or a cluster of them. Higher plants are endowed with well-developed tissues, have roots, leaves, and stems.
- In algae, asexual reproduction predominates, by dividing the original mother cell. They are also characterized by vegetative and sexual division. Higher spore plants are characterized by a strict alternation of sexual and asexual generations.
- What organelles are absent in higher cells, but are characteristic of lower species? These are centrioles that are also present in animals.
Similarities:
- Method of nutrition - both groups of plants are photoautotrophs.
- Cell structure: presence of cell wall, chlorophyll, nutrients.
- They cannot actively move; two phases alternate in their life cycle: gametophyte and sporophyte.
Higher plants are inhabitants of the terrestrial-air environment, which is fundamentally different from the aquatic environment.
Higher plants are leafy plants, many have roots. Based on these characteristics, in Latin they are called Cormophyta (from the Greek kormos - trunk, stem, phyton - plant) in contrast to algae - Thallophyta (from the Greek thallos - thallus, thallus, phyton - plant).
The organs of higher plants have a complex structure. Their conducting system is represented by special cells - trachea and dams, as well as vessels, sieve tubes. Conducting elements are grouped into regular combinations - vascular-fibrous bundles. In higher plants, a central cylinder appears on the body. First, the central cylinder is simple - proto stela (from the Greek protos - simple, stela - column, pillar). Then more complex steles appear: actino stela (from the Greek actis - ray), plekto stela (from the Greek plectos - twist, twist), s and pho n o - st e l a (from the Greek. siphon - tube), art h o st e l a (from the Greek. arthrus - jointed), d i c t i o st e l a ( from the Greek diktyon - network), e v st e la (from the Greek eu - real), and a t a st e l a (from the Greek ataktos - disorderly).
Higher plants have a complex system of integumentary tissues (epiderma, periderma, crust), and a complex stomatal apparatus appears. Under the conditions of terrestrial and aerial life, powerfully developed mechanical tissues appear in higher plants.
The reproductive organs of higher plants - multicellular antherids (male) and archegoniums (female) - probably originated from multicellular gametangia algae such as dictyota and ectocorpus (from brown algae).
A characteristic feature of higher plants is the alternation of generations in the development cycle - gametophyte (sexual) and sporophyte (asexual) and the corresponding change of nuclear phases (haploid and diploid). The transition from the haploid nuclear phase to the diploid phase occurs when the egg is fertilized by sperm or sperm. And vice versa, the transition from diploid nuclear phase to haploid occurs during the formation of spores from sporogenous tissue - a r x e -spores by meiosis with a reduction in the number of chromosomes.
Origin of higher plants.
Higher plants probably evolved from some kind of algae. This is evidenced by the fact that in the geological history of the plant world, higher plants were preceded by algae. The following facts also support this assumption: the similarity of the most ancient extinct group of higher plants - rhiniophytes - with algae, the very similar nature of their branching; similarity in the alternation of generations of higher plants and many algae; the presence of flagella and the ability for independent swimming in male germ cells of many higher plants; similarities in the structure and function of chloroplasts.
It is assumed that higher plants most likely originated from green algae, freshwater or brackish water. They had multicellular gametangia, an isomorphic alternation of generations in the development cycle.
The first land plants found in fossil form were rhiniophytes (rhinia, hornea, horneophyton, sporogonytes, psilophyte, etc.).
After reaching land, higher plants developed in two main directions and formed two large evolutionary branches - haploid and diploid.
The haploid branch of the evolution of higher plants is represented by the bryophyte department (Bryophyta) . In the development cycle of mosses, the gametophyte, the sexual generation (the plant itself), predominates, and the sporophyte, the asexual generation, is reduced and is represented by a sporogon in the form of a box on a stalk. The development of bryophytes went towards increasing independence of the gametophyte and its gradual morphological division, loss of independence of the sporophyte and its morphological taming. The gametophyte became an independent, completely autotrophic phase of the life cycle of bryophytes, and the sporophyte was reduced to the level of a gametophyte organ.
Mosses, as representatives of the haploid branch of the evolution of higher plants, turned out to be less viable and adapted to living conditions on Earth. Their distribution is associated with the presence of free drop-liquid water, necessary not only for growth processes, but also for the sexual process. This explains their ecological confinement to places where there is constant or periodic moisture.
The second evolutionary branch of higher plants is represented by all other higher plants.
The sporophyte in terrestrial conditions turned out to be more viable and adapted to a variety of environmental conditions. This group of plants conquered land more successfully. Their sporophyte is often large in size and has a complex internal and external structure. The gametophyte, on the contrary, has undergone simplification and reduction.
In simpler forms (spore-bearing plants), the gametophyte still has an independent existence and is represented by an autotrophic or symbiotrophic prothallus (Lycopodiophyta, equisetophyta, Polypodiophyta) , and in heterosporous representatives of these departments it is significantly simplified and reduced. In more organized - seed plants - the gametophyte has lost its independent way of life and develops on the sporophyte, and in angiosperms (flowering plants) it is reduced to several cells.
Under the new conditions, there was a gradual increase in complexity of terrestrial plants with the predominance of the sporophyte in the development cycle. They gave rise to a number of independent groups (divisions) of plants adapted to various living conditions on land.
Currently, higher plants number over 300,000 species. They dominate the Earth, inhabiting it from the Arctic territories to the equator, from the humid tropics to dry deserts. They form various types of vegetation - forests, meadows, swamps, and fill water bodies. Many of them reach gigantic sizes (sequoiadendron - 132 m with a girth of 35 m, giant eucalyptus - 152 m (Flindt, 1992), rootless wolfia - 0.1-0.15 cm (Identifier of plants of Belarus, 1999).
Despite the enormous diversity of appearance and internal structure, all higher plants retain a certain unity in structure. Higher plants are divided into 9 divisions. However, they are relatively easily linked with each other, which indicates the unity of origin of higher plants.
SYSTEMATICS OF HIGHER PLANTS
General characteristics of higher plants. The most ancient representatives
Lecture outline:
1. The concept of “higher plant”.
3. “Higher plant” syndrome.
4. Time of appearance of higher plants.
5. Sexual and asexual reproduction of plants.
6. Hypotheses of the origin of higher plants.
7. The most ancient higher plants.
The concept of “higher plant”
Higher plants, or Embryobionta, – embryonic plants, or Cormophyta, Cormobionta- shoot plants, or Telomophyta, Telomobionta- telomic plants. This is one of the two subkingdoms of the plant world. Higher plants unite over 300 thousand species of the following taxonomic groups (divisions): rhiniums (psilophytes), bryophytes (liverworts and mosses), psilotaceae (psilotum and tmesipteris), mosses, horsetails, ferns, gymnosperms and flowering or angiosperms. Unlike lower plants higher are more complex, differentiated multicellular organisms that are adapted to life on land (with the exception of a few and clearly secondary aquatic forms), have a regular alternation of two generations, i.e. sexual (gametophyte) and asexual (sporophyte). On sporophytes, they develop multicellular sporangia filled with immobile spores that have a strong shell; on gametophytes, multicellular reproductive organs (gametangia) develop. However, in some gymnosperms (some of the Gnetaceae) and in all flowering plants, gametangia disappeared during the process of evolution.
Higher plants have a taxonomic status. They are in the rank of the sub-kingdom of the highest (Embryobionta), along with the lower ones (Thallobionta), belong to the plant kingdom (Vegetabilia, Chlorobionta, Plantae), superkingdom of eukaryotes (Eucaryota). Thus, they are united by the characteristics of taxa of the rank of kingdom and superkingdom. Like eukaryotes, higher and lower plants have a formed nucleus, equipped with a typical shell (double membrane) and nucleolus; there is an extranuclear mitotic apparatus in the form of microtubules, mitochondria, Golgi apparatus, kinetosomes, flagella and other organelles; the cell wall includes chitin or cellulose; The sexual process and the change of nuclear phases, haploid and diploid, are presented.
There are currently, apparently, much more than 300 thousand species of higher plants. And they are distributed among the main departments as follows: mosses - 26,000–30,000 species; mosses – 1200 species; horsetails – 29 species; psilotaceae – 12 species; ferns – 10,000 species, gymnosperms – about 600 species; angiosperms – 250–300 thousand species.
"Higher Plant" Syndrome
Higher plants, apparently originating from algae, adapt to the conditions of land that was not previously effectively inhabited (the end of the Silurian period of the Paleozoic era, about 420-440 million years ago). At the same time, they develop significant features that are of key importance for survival in terrestrial conditions: tissue structure (non-thallus); presence of stomata; triradiate spores with dense, inert shells; multicellular organs of sexual reproduction, i.e. archegonia (female) and antheridia (male); natural alternation in the life cycle of sexual and asexual generations with a tendency towards the predominance of the sporophyte (in mosses - the gametophyte); the initial level of somatic organization is the body. Subsequently, the syntelome, preshoot and shoot appear.
In conditions of terrestrial life, reproduction by spores acquires particular importance. On land, a huge number of spores find themselves in unsuitable conditions for germination and die. There is a need to produce a very large number of spores, which requires the accumulation of a sufficient amount of organic matter. This should lead to an increase in the size of the sporophyte and the area of its photosynthetic surface. In addition, it is accompanied by its external and internal dismemberment. Increasing dismemberment is accompanied by the appearance of a conducting system and special multicellular spore containers - sporangia.
Already the most primitive terrestrial plants were differentiated into elementary organs: cauloid and rhizomoid. Cauloid is an orthotropic axis, rhizomoid is a plagiotropic axis. Together they make up the body. A characteristic feature of teloms is localized apical growth. The origin of telomes is associated with increasing dichotomous branching. A rhizomoid is not a rhizome, but only its analogue. Unlike a real rhizome (modified shoot), the rhizomoid is a primary elementary organ. The appearance of the body increased plasticity and opened up greater opportunities for further evolutionary development. The terminal position of the sporangia, characteristic of the body, in rhinophytes leads to the fact that the sporangia are modified tips of the branches.
Time of appearance of higher plants
According to available paleontological data, this happened approximately 440 million years ago (Silurian period of the Paleozoic era). There is a well-known point of view that some algae that lived near the shore first “stuck their heads into the air,” then populated the tidal zone, and then, gradually turning into higher plants, came entirely to the shore. Subsequently, they gradually conquered the land. However, serious paleontological objections were later raised against this point of view.
If the process of transformation of algae into higher plants actually took place in coastal waters, then in this case the conditions for getting into the paleontological record of the most ancient higher plants are most favorable. However, given the abundance of paleobotanical material, we do not see any of its “intermediate” stages.
This paradox led to the emergence of an unusual, at first glance, hypothesis: why should the appearance of macroremains of higher plants at the end of the Silurian be unambiguously interpreted as traces of their emergence onto land? Perhaps, quite the opposite - these are traces of the migration of higher plants into water? In any case, a number of paleobotanists (G. Stebbins, G. Hill and S.V. Meyen) adhere to the hypothesis about the origin of higher plants not from lower aquatic plants, but from some kind of terrestrial green algae. It was these “non-aquatic” higher plants that had no real chance of being included in the geological record that could have belonged to spores with a triradiate fissure, which were very numerous in the Early Silurian and even in the Late Ordovician and were not correlated with any aquatic plants known at that time.
Let's read the information
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Higher plants- organisms that have a morphological division of the body into vegetative organs, the main of which are the shoot and the root.
Peculiarities higher plants:
- always have a morphological division of the body into vegetative organs (shoot, root, leaf, stem, bud). Algae (lower plants) do not have true roots, shoots, leaves, stems or buds.
- always have a multicellular structure of organs of sexual and asexual reproduction (gametangia: male - antheridia, female - archegonia).
- always in the process of fusion of gametes a zygote is formed, which always gives rise to an embryo (in lower plants, after the division of the zygote, the cells are immediately used to build the thallus)
- always have two life phases that naturally replace each other - gametophyte and sporophyte (in lower plants, phase changes occur at different stages, and therefore several types of reduction are distinguished - gametic, sporic, zygotic).
- always have tissues, main groups: educational, basic, conductive, integumentary, mechanical, excretory (not present in primitive unicellular algae)
Features of bryophytes:
- Bryophytes are the only division of higher plants in which (the haploid life phase) is the predominant generation.
- simplicity of cell structure
- simplicity of the structure of the body - the absence of real vegetative organs (the "stem" is not a real "stem" - and the "leaf" is not a real "leaf" - in the simplest ones the body is a thallus)
- have no roots (attached to the substrate by filiforms)
- the majority lack conductive, mechanical tissues, and other tissues are poorly developed
- class pteridophytes
- class lycophytes
- class Equisetae (segmented)
- In all plants, the predominant generation is the sporophyte (diploid life phase)
- do not have true leaves (their “leaves” are called planum, or preshoot)
- have no flowers or seeds.
- They reproduce only by spores (sporangia).
- Fertilization is possible only in the presence of drip-liquid water.
- coniferous class
- The department includes only woody forms of plants (trees and shrubs).
- most are evergreens (adaptations that increase winter hardiness).
- do not have flowers or fruits, the seeds are located openly - in scales or cones (male and female).
- there are no real vessels in the wood (adaptation - needle-shaped leaves for less moisture evaporation).
- class dicotyledons
- class monocots
- reproduction with the formation of seeds.
- always internal fertilization.
- In addition to seeds, spores are also formed.
- life phases always successively replace each other (the sporophyte always predominates, and the gametophyte undergoes a strong reduction and develops inside the spore)
- all seed plants are heterosporous
- In the process of reproduction there is a stage - pollination
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Bryophytes |
Marchantia, cuckoo flax, sphagnum, etc. |
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Ferns |
Ferns |
Male shieldweed, bracken, salvinia (water fern), southern actiniopteris, etc. |
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Moss-moss |
Moss clubmoss, selaginella, polushnik, etc. |
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Horsetails (segmented) |
Horsetail, marsh horsetail, forest horsetail, etc. |
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Spruce, pine, larch, cypress, cedar, fir, juniper, sequoia, yew, kauri, etc. |
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Angiosperms (flowering) |
Dicotyledons |
Real lady's slipper, durum wheat, edible cornwort, swamp butterfly, etc. |
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Monocots |
Amborella, white water lily, creeping buttercup, Dutch clove, buckwheat, rhubarb, spinach, geranium, birch, alder, hornbeam, calendula, sunflower, etc. |
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Literature used:
1.Biology: a complete reference book for preparing for the Unified State Exam. / G.I. Lerner. - M.: AST: Astrel; Vladimir; VKT, 2009 2.Biology: Plants, bacteria, fungi, lichens: textbook. for 6-7 grades. general education Institutions / T.I.Serebryakova, A.G.Elenevsky, M.A. Gulenkova and others - 5th ed. - M.: Education, 1999. 3. Biology for those entering universities. Intensive course / G.L.Bilich, V.A.Kryzhanovsky. - M.: Onyx Publishing House, 2006. 4. Biology: textbook / reference manual / A.G. Lebedev. M.: AST: Astrel. 2009. 5.Biology. Full course of general secondary school: a textbook for schoolchildren and applicants / M.A. Valovaya, N.A. Sokolova, A.A. Kamensky. - M.: Exam, 2002.
Internet resources used:
Wikipedia - the free encyclopedia
Links Wikipedia. Sporophyte http://ru.wikipedia.org/wiki/%D0%A1%D0%BF%D0%BE%D1%80%D0%BE%D1%84%D0%B8%D1%82 Wikipedia. Gametophyte http://ru.wikipedia.org/wiki/%D0%93%D0%B0%D0%BC%D0%B5%D1%82%D0%BE%D1%84%D0%B8%D1%82 Nature and animals
The plant kingdom amazes with its greatness and diversity. Wherever we go, no matter what corner of the planet we find ourselves in, we can find representatives of the plant world everywhere. Even the ice of the Arctic is no exception for their habitat. What is this plant kingdom? The species of its representatives are diverse and numerous. What are the general characteristics of the plant kingdom? How can they be classified? Let's try to figure it out.
General characteristics of the plant kingdom
All living organisms can be divided into four kingdoms: plants, animals, fungi and bacteria.
The characteristics of the plant kingdom are as follows:
- are eukaryotes, that is, plant cells contain nuclei;
- are autotrophs, that is, they form organic substances from inorganic substances during photosynthesis using the energy of sunlight;
- lead a relatively sedentary lifestyle;
- unlimited in growth throughout life;
- contain plastids and cell walls made of cellulose;
- starch is used as a reserve nutrient;
- presence of chlorophyll.
Botanical classification of plants
The plant kingdom is divided into two subkingdoms:
- lower plants;
- higher plants.
Subkingdom "lower plants"
This subkingdom includes algae - the simplest in structure and the most ancient plants. However, the world of algae is very diverse and numerous.
Most of them live in or on the water. But there are algae that grow in the soil, on trees, on rocks and even in ice.
The body of algae is a thallus or thallus, which has neither roots nor shoots. Algae do not have organs or various tissues; they absorb substances (water and mineral salts) over the entire surface of the body.
The subkingdom “lower plants” consists of eleven divisions of algae.
Significance for humans: release oxygen; are eaten; used to produce agar-agar; are used as fertilizers.
Subkingdom "higher plants"
Higher plants include organisms that have well-defined tissues, organs (vegetative: root and shoot, generative) and individual development (ontogenesis) which are divided into embryonic (embryonic) and postembryonic (post-embryonic) periods.
Higher plants are divided into two groups: spore plants and seed plants.
Spore-bearing plants spread through spores. Reproduction requires water. Seed plants spread by seeds. Water is not needed for reproduction.
Spore plants are divided into the following sections:
- bryophytes;
- lycophytes;
- horsetails;
- fern-like.
Seeds are divided into the following sections:
- angiosperms;
- gymnosperms.
Let's look at them in more detail.
Department "bryophytes"
Bryophytes are low-growing herbaceous plants, the body of which is divided into a stem and leaves; they have a kind of roots - rhizoids, the function of which is to absorb water and anchor the plant in the soil. Besides photosynthetic and ground tissue, mosses have no other tissues. Most mosses are perennial plants and grow only in moist areas. Bryophytes are the most ancient and simplest group. At the same time, they are quite diverse and numerous and are second only to angiosperms in the number of species. There are about 25 thousand of their species.
Bryophytes are divided into two classes - liver and phyllophytes.
Liverworts are the most ancient mosses. Their body is a branched flat thallus. They live mainly in the tropics. Representatives of liverworts: mosses Merchantia and Riccia.
Leafy mosses have shoots that consist of stems and leaves. A typical representative is cuckoo flax moss.
In mosses, sexual and asexual reproduction is possible. Asexual can be either vegetative, when the plant reproduces by parts of stems, thallus or leaves, or spore-bearing. During sexual reproduction in bryophytes, special organs are formed in which immobile eggs and motile sperm mature. Sperm move through the water to the eggs and fertilize them. Then a capsule with spores grows on the plant, which, after maturation, scatter and spread over long distances.
Mosses prefer damp places, but they grow in deserts, on rocks, and in tundras, but they are not found in the seas and on highly saline soils, in shifting sands and glaciers.
Importance for humans: peat is widely used as fuel and fertilizer, as well as for the production of wax, paraffin, paints, paper, and in construction it is used as a heat-insulating material.
Divisions "mocophytes", "tail-like" and "fern-like"
These three divisions of spore plants have similar structure and reproduction, most of them grow in shady and moist places. Woody forms of these plants are very rare.
Ferns, club mosses and horsetails are ancient plants. 350 million years ago they were large trees, they were the forests on the planet, in addition, they are the sources of coal deposits at the present time.
The few plant species of the fern, horsetail and lycophyte divisions that have survived to this day can be called living fossils.
Externally, different types of mosses, horsetails and ferns are different from each other. But they are similar in internal structure and reproduction. They are more complex in structure than mossy plants (they have more tissue in their structure), but simpler than seed plants. They belong to spore plants, since they all form spores. Both sexual and asexual reproduction are also possible for them.
The most ancient representatives of these orders are club mosses. Nowadays, club moss can be found in coniferous forests.
Horsetails are found in the Northern Hemisphere, now they are represented only by herbs. Horsetails can be found in forests, swamps and meadows. A representative of the horsetails is horsetail, which usually grows in acidic soils.
Ferns are a fairly large group (about 12 thousand species). Among them there are both grasses and trees. They grow almost everywhere. Representatives of ferns are ostrich and bracken.
Significance for humans: ancient pteridophytes gave us deposits of coal, which is used as fuel and valuable chemical raw materials; some species are used for food, used in medicine, and used as fertilizers.
Department "angiosperms" (or "flowering")
Flowering plants are the most numerous and highly organized group of plants. There are more than 300 thousand species. This group makes up the bulk of the planet's vegetation. Almost all representatives of the plant world that surround us in everyday life, both wild and garden plants, are representatives of angiosperms. Among them you can find all life forms: trees, shrubs and herbs.
The main difference between angiosperms is that their seeds are covered with a fruit formed from the ovary of the pistil. The fruit protects the seed and promotes its distribution. Angiosperms produce flowers, the organ of sexual reproduction. They are characterized by double fertilization.
Flowering plants dominate the vegetation cover as the most adapted to modern living conditions on our planet.
Value for humans: used for food; release oxygen into the environment; used as building materials and fuel; used in the medical, food, and perfume industries.
Department "gymnosperms"
Gymnosperms are represented by trees and shrubs. There are no herbs among them. Most gymnosperms have leaves in the form of needles. Among gymnosperms, a large group of conifers stands out.
About 150 million years ago, conifers dominated the planet's vegetation.
Significance for humans: form coniferous forests; release large amounts of oxygen; used as fuel, building materials, shipbuilding, and furniture manufacturing; used in medicine and in the food industry.
Diversity of flora, plant names
The above classification continues; departments are divided into classes, classes into orders, followed by families, then genera and, finally, plant species.
The plant kingdom is huge and diverse, so it is customary to use botanical names for plants that have a double name. The first word in the name means the genus of plants, and the second means the species. This is what the taxonomy of the well-known chamomile will look like:
Kingdom: plants.
Department: flowering.
Class: dicotyledonous.
Order: astroflora.
Family: Asteraceae.
Genus: chamomile.
Type: chamomile.
Classification of plants according to their life forms, description of plants
The plant kingdom is also classified according to life forms, that is, according to the external appearance of the plant organism.
- Trees are perennial plants with lignified aerial parts and a distinct single trunk.
- Shrubs are also perennial plants with lignified aerial parts, but, unlike trees, they do not have a clearly defined one trunk, and branching begins near the ground and several equal trunks are formed.
- Shrubs are similar to shrubs, but are low-growing - no higher than 50 cm.
- Subshrubs are similar to shrubs, but differ in that only the lower parts of the shoots are lignified, and the upper parts die off.
- Lianas are plants with clinging, climbing and climbing stems.
- Succulents are perennial plants with leaves or stems that store water.
- Herbs are plants with green, succulent and non-woody shoots.
Wild and cultivated plants
Humans have also contributed to the diversity of the plant world, and today plants can also be divided into wild and cultivated.
Wild - plants in nature that grow, develop and spread without human help.
Cultivated plants come from wild plants, but are obtained through selection, hybridization or genetic engineering. These are all garden plants.