The plant kingdom is striking in its greatness and diversity. Wherever we go, in whatever corner of the planet we find ourselves, everywhere you can meet representatives of the plant world. Even the ice of the Arctic is no exception for their habitat. What is the plant kingdom? Its species are varied and numerous. What is the general characteristic of the plant kingdom? How can they be classified? Let's try to figure it out.
All living organisms can be divided into four kingdoms: plants, animals, fungi and bacteria.
The signs of the plant kingdom are as follows:
The plant kingdom is divided into two sub-kingdoms:
This sub-kingdom 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 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 root nor shoots. Algae do not have organs and various tissues; they absorb substances (water and mineral salts) through the entire surface of the body.
The sub-kingdom "lower plants" consists of eleven divisions of algae.
Significance for humans: release oxygen; are used for food; used to obtain agar-agar; are used as fertilizers.
Higher plants include organisms that have well-defined tissues, organs (vegetative: root and shoot, generative) and individual development (ontogenesis) of which is divided into embryonic (embryonic) and postembryonic (postembryonic) periods.
Higher plants are divided into two groups: spore and seed.
Spore plants spread by means of spores. Reproduction requires water. Seed plants are propagated by seeds. Reproduction does not require water.
Spore plants are divided into the following sections:
Seeds are divided into the following departments:
Let's consider them in more detail.
Bryophytes are low-growing herbaceous plants whose body is divided into a stem and leaves, they have a kind of roots - rhizoids, the function of which is to absorb water and fix the plant in the soil. In addition to photosynthetic and basic tissue, mosses have no other tissues. Most mosses are perennials and only grow in damp places. Bryophytes are the oldest and simplest group. At the same time, they are quite diverse and numerous and are inferior in the number of species only to angiosperms. There are about 25 thousand of their species.
Bryophytes are divided into two classes - hepatic and leafy.
Liverworts are the most ancient mosses. Their body is a branched flat thallus. They live mainly in the tropics. Representatives of the liverworts: mosses merchantsia and riccia.
Leafy mosses have shoots that consist of stems and leaves. A typical representative is cuckoo flax moss.
Mosses can reproduce both sexually and asexually. Asexual can be either vegetative, when the plant reproduces by parts of stems, thallus or leaves, or spore. During sexual reproduction in mosses, special organs are formed in which immobile eggs and motile spermatozoa mature. Spermatozoa move through the water to the eggs and fertilize them. Then a box with spores grows on the plant, which, after maturation, crumble and spread over long distances.
Mosses prefer wet places, but they grow in deserts, and on rocks, and in tundra, but they are not found in the seas and on highly saline soils, in loose sands and glaciers.
Significance for humans: peat is widely used as a fuel and fertilizer, as well as for the production of wax, paraffin, paints, paper, in construction it is used as a heat-insulating material.
These three divisions of spore plants have a similar structure and reproduction, most of them grow in shady and humid 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, it was they who made up the forests on the planet, in addition, they are the sources of coal deposits at the present time.
A few plant species of the fern-like, horsetail-like and club-like divisions that have survived to this day can be called living fossils.
Externally, different types of club mosses, horsetails and ferns are different from each other. But they are similar in internal structure and reproduction. They are more complex than bryophytes (they have more tissues in their structure), but simpler than seed plants. They belong to spore plants, since they all form spores. They can also reproduce both sexually and asexually.
The most ancient representatives of these groups are club mosses. Today, in coniferous forests, you can find club-shaped club moss.
Horsetails are found in the Northern Hemisphere, now they are represented only by herbs. Horsetails can be found in forests, swamps and meadows. The representative of horsetails is field horsetail, which usually grows on acidic soils.
Ferns are a fairly large group (about 12 thousand species). Among them there are both herbs and trees. They grow almost everywhere. Representatives of ferns are the ostrich and the common bracken.
Significance for humans: the ancient ferns gave us deposits of coal, which is used as fuel and valuable chemical raw materials; some species are used for food, used in medicine, used as fertilizers.
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 cover. 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 grasses.
The main difference between angiosperms is that their seeds are covered with a fruit formed from the ovary of the pistil. The fruit is the protection of the seed and promotes their spread. Angiosperms form flowers - the organ of sexual reproduction. They are characterized by double fertilization.
Flowering plants dominate the vegetation cover as the most adapted to the modern conditions of life on our planet.
Value for the person: are used in food; release oxygen into the environment; are used as building materials, fuel; are used in the medical, food, perfume industries.
Gymnosperms are represented by trees and shrubs. There are no herbs among them. Most gymnosperms have leaves in the form of needles (needles). Among the gymnosperms, a large group of conifers stands out.
About 150 million years ago, coniferous plants dominated the vegetation cover of the planet.
Significance for humans: form coniferous forests; release large amounts of oxygen used as fuel, building materials, shipbuilding, furniture manufacturing; are applied in medicine, in the food industry.
The above classification has a continuation, the departments are subdivided into classes, classes into orders, then families, then genera, and finally plant species.
The plant kingdom is vast and diverse, so it is customary to use botanical plant names that have a double name. The first word in the name means the genus of plants, and the second - the species. Here is how the taxonomy of the well-known chamomile will look like:
Kingdom: plants.
Department: flower.
Class: dicot.
Order: astrocolor.
Family: aster.
Genus: chamomile.
Type: chamomile.
The plant kingdom is also classified according to life forms, that is, according to the external appearance of the plant organism.
Man also had a hand in the diversity of the plant world, and today plants can also be divided into wild and cultivated.
Wild-growing - plants in nature that grow, develop and spread without human help.
Cultivated plants originate from wild plants, but are obtained by selection, hybridization or genetic engineering. These are all garden plants.
An organ is a part of a plant that has a certain external (morphological) and internal (anatomical) structure in accordance with its function. There are vegetative and reproductive organs of a plant.
The main vegetative organs are the root and shoot (stem with leaves). They provide the processes of nutrition, conduction and substances dissolved in it, as well as vegetative reproduction.
Reproductive organs (spore-bearing spikelets, strobili or cones, flower, fruit, seed) perform functions associated with sexual and asexual reproduction of plants and ensure the existence of the species as a whole, its reproduction and distribution.
The dismemberment of the body of plants into organs, the complication of their structure occurred gradually in the process of development of the plant world. The body of the first land plants - rhinophytes, or psilophytes - was not divided into roots and leaves, but was represented by a system of branching axial organs - telomes. As plants emerged onto land and adapted to life in air and soil environments, telomes changed, which led to the formation of organs.
In algae, fungi and lichens, the body is not differentiated into organs, but is represented by a thallus, or thallus of a very diverse appearance.
During the formation of organs, some general patterns are found. With the growth of the plant, the size and weight of the body increase, cells divide and stretch in a certain direction. The first stage of any neoplasm is the orientation of cellular structures in space, i.e. polarity. In higher seed plants, polarity is already found in the zygote and the developing embryo, where two rudimentary organs are formed: a shoot with an apical bud and a root. The movement of many substances occurs along the conductive paths polarly, i.e. in a certain direction.
Another pattern is symmetry. It manifests itself in the location of the side parts in relation to the axis. There are several types of symmetry: radial - two (or more) planes of symmetry can be drawn; bilateral - only one plane of symmetry; at the same time, dorsal (dorsal) and ventral (abdominal) sides are distinguished (for example, leaves, as well as organs growing horizontally, i.e. having plagiotropic growth). , growing vertically - orthotropic - have radial symmetry.
In connection with the adaptation of the main organs to new specific conditions, their functions change, which leads to their modifications, or metamorphoses (tubers, bulbs, spines, buds, flowers, etc.). In plant morphology, homologous and similar organs are distinguished. Homologous organs have the same origin, but may differ in form and function. Similar organs perform the same functions and have the same appearance, but are different in their origin.
The organs of higher plants are characterized by oriented growth (, which is a response to the unilateral action of external factors (light, gravity, humidity). The growth of axial organs towards the light is defined as positive (shoots) and negative (main root) phototropism. Oriented growth of the axial organs of a plant, caused by the unilateral action of the force of gravity, is defined as geotropism.Positive geotropism of the root causes its directed growth towards the center, negative geotropism of the stem - from the center.
The shoot and root are in their infancy in the embryo in the mature seed. The embryonic shoot consists of an axis (embryonic stalk) and cotyledon leaves, or cotyledons. The number of cotyledons in the embryo of seed plants ranges from 1 to 10-12.
At the end of the axis of the embryo is the growth point of the shoot. It is formed by the meristem and often has a convex surface. This is the cone of growth, or apex. At the top of the shoot (apex), the rudiments of leaves are laid in the form of tubercles or ridges following the cotyledons. Typically, leaf buds grow faster than the stem, with young leaves covering each other and the growing point, forming a bud of the embryo.
The part of the axis where the bases of the cotyledons are located is called the cotyledon node; the rest of the germinal axis, below the cotyledons, is called the hypocotyl, or hypocotyl knee. Its lower end passes into the germinal root, represented so far only by a cone of growth.
When the seed germinates, all the organs of the embryo gradually begin to grow. The germinal root emerges first from the seed. It strengthens the young plant in the soil and begins to absorb water and minerals dissolved in it, giving rise to the main root. The area on the border between the main root and the stem is called the root collar. In most plants, the main root begins to branch, while lateral roots of the second, third and higher orders appear, which leads to the formation of the root system. On the hypocotyl, on old parts of the root, on the stem, and sometimes on the leaves, adventitious roots can form quite early.
Almost simultaneously, a shoot of the first order, or the main shoot, develops from the germinal bud (apex), which also branches, forming new shoots of the second, third and higher orders, which leads to the formation of the main shoot system.
As for the higher spore shoots (mosses, horsetails, ferns), their body (sporophyte) develops from the zygote. The initial stages of the life of a sporophyte take place in the tissues of the outgrowths (gametophytes). An embryo develops from a zygote, consisting of a rudimentary shoot and a root pole.
So, the body of any higher plant consists of shoot and (except mossy) root systems, built from repeating structures - shoots and roots.
In all organs of a higher plant, three tissue systems - integumentary, conductive and main - continuously continue from organ to organ, reflecting the integrity of the plant organism. The first system forms the outer protective cover of plants; the second, including phloem and xylem, is immersed in the system of basic tissues. The fundamental difference in the structure of the root, stem and leaf is determined by the different distribution of these systems.
During the primary growth, which begins near the tops of the roots and stems, primary ones are formed that make up the primary body of the plant. The primary xylem and primary phloem and their associated parenchymal tissues form the central cylinder, or stele, of the stem and root of the primary plant body. There are several types of steles.
Higher plants include all terrestrial leafy plants that reproduce by spores or seeds.
The main differences between higher and lower plants:
1) Habitat: in the lower ones - water, in the higher ones - mostly land.
2) The development of various tissues in higher plants- conductive, mechanical, integumentary, of which the organs are composed.
3) The presence of vegetative organs in higher plants:
- Root- fixation in the soil and water-mineral nutrition
- Sheet- photosynthesis
- Stem- transport in-in (upward and downward currents)
(stem with leaves + buds = shoot)
4) Higher plants have integumentary tissue- the epidermis, which performs protective functions
5) Enhanced mechanical stability of the stem of higher plants due to the thick cell wall, impregnated with lignin.
6) Reproductive organs: in most lower plants - unicellular, in higher plants - multicellular. The reproductive organs of higher plants are formed in different generations: gametophyte(anteridia and archegonia) and sporophyte(sporangia).
Based on the characteristics that higher plants have, they are called: stomatal, germinal, shoot, telomous and vascular plants.
vascular plants- all higher plants, with the exception of mosses.
Higher plants are descended from green, freshwater or brackish-water heterotrichal algae. The first higher plants were rhinophytes- leafless, biochotomous plants. The terminal branches of these plants are called tellomas.
In the development cycle of all higher plants, with the exception of mosses, sporophyte. Only in mosses does the gametophyte predominate over the sporophyte.
Plants are : 1) Equosporous- they form the same spores and each spore germinates into a different-sex gametophyte.
2) Heterosporous A female gametophyte develops from a female spore, and a male gametophyte develops from a male spore.
Spore is a mononuclear, haploid cell (n) with 2 shells.
Spore plants:
Rhyniophyta - fossil plants (Rhyniophyta)
Bryophytes
psilophyd
Lycopsformes
horsetail
Ferns
Fertilization requires water
Higher seed plants:
Department Flowering (Angiosperms)
Fertilization does not require water
BRYOSH- the most primitive, oldest group of higher plants, appeared about 400 million years ago.
Number of species: Currently, bryologists have described about 20 thousand species of mosses.
Moss habitat: bryophytes are distributed everywhere (settle on the soil, rocks, stumps, trees), except for the seas and highly saline soils, they are found even in Antarctica. Mosses prefer shady moist places.
Moss body structure: mosses are low-growing perennial herbaceous plants ranging in size from 1 mm to several centimeters, less often up to 60 cm or more. The moss body is either divided into a stem (caulidia) and small leaves (phylloids), such as sphagnum and cuckoo flax, or is represented by a thallus that is not divided into organs (marchantia). A characteristic feature of all bryophytes- lack of roots. The absorption of water and attachment to the substrate is carried out in them by rhizoids, which are outgrowths of the epidermis. The absorption and evaporation of water is carried out by the entire surface of the gametophyte.
Bryophytes do not have a developed conducting system (tracheids, vessels, sieve tubes). There are both monoecious and dioecious plants. Their internal structure is relatively simple. For bryophytes, as for all higher plants, the correct alternation of sexual and asexual generations is characteristic. The development cycle is dominated by the haploid gametophyte (constituting the main body of the plant). Sporophyte - does not contain chlorophyll and is attached to the gametophyte for life and feeds on it.
The development of mosses is very interesting. Fertilization is possible only in the presence of water, since spermatozoa can move in it. On one plant, male cells with flagella are formed, on the other plant, on the very tops, large female cells mature. During rain or fog, mobile male cells in a drop of water rush to female cells and merge with them. From the fertilized female cell (zygote) develops a sporophyte, which is called sporogon(he is box with leg, extended at the bottom of the foot - haustoria, with the help of which he, sticking to the gametophyte, lives at the expense of it).
(caliptra-remnant of the abdomen of the archegonium)
The relationship between gametophyte and sporophyte is very limited. The gametophyte not only nourishes, but also protects the sporophyte generation, helps in dispersing spores (“false leg” raises the box above the plant, archegonium, bursting with its abdomen, covers the box).
A huge amount of spores are formed in the box. Each spore is smaller than a grain of semolina. When the spores mature, the lid of the box opens, or small pores form in it, through which the spores fly out to freedom. Once in favorable conditions, the dispute germinates. The individual life of bryophytes begins with the germination of spores. Most often, when the spore swells, the exine bursts, and the intine, together with the content of the spore, is elongated and gives rise to a single-row filament or a single-layer plate bearing rhizoids. This is the initial stage of gametophyte development called protonema(from Greek protos - primary, nema - thread). It either gradually turns into an adult thallus gametophyte (in liverworts), or buds are formed on the protonema, giving rise to an adult leafy gametophyte).
Bryophytes reproduce vegetatively with the help of special organs (brood buds, leaves, parts of leaves, twigs), and the sporophyte (leg) is also able to reproduce vegetatively.
Mosses are capable of accumulating many substances, including radioactive ones. Some bryophytes (Sphagnum) have antibiotic properties and are used in medicine. Peat deposits, formed mainly by sphagnum mosses, have long been exploited as a source of fuel and organic fertilizers. The bryophyte division is divided into three classes: 1) Hornflowers(Anthocerotes); 2 )liverworts(Marchantia is diverse); 3) Leafy mosses(cuckoo flax, sphagnum).
660-01. A specialized organ of air nutrition of a plant is
A) green leaf
B) root crop
B) a flower
D) fruit
Answer
660-02. What role do roots play in plant life?
A) form organic compounds from inorganic compounds
B) cool plants
B) store organic matter
D) take in carbon dioxide and release oxygen
Answer
660-03. The main function of the root is
A) food storage
B) soil plant nutrition
C) absorption of organic matter from the soil
D) oxidation of organic substances
Answer
660-04. What is the most important role of the leaf in the life of the plant?
A) allows water to evaporate
B) performs a supporting function
B) is used as a protective organ
D) absorbs water and mineral salts
Answer
660-05. Under what conditions can water rise up in a plant?
A) in the absence of water evaporation
B) with constant evaporation of water
B) only during the day
D) only with closed stomata
Answer
660-06. The main role of leaves in plant life is
A) breathing
B) storage
B) photosynthetic
D) vegetative propagation
Answer
660-07. Evaporation of water from leaves contributes to
A) the movement of mineral salts in the plant
B) supplying leaves with organic matter
C) absorption of carbon dioxide by chloroplasts
D) increase the rate of formation of organic substances
Answer
660-08. The main function of the stem is
A) air nutrition of plants
B) storage of water and nutrients
B) carrying water and nutrients
D) evaporation of water
Answer
660-09. Which of the following is an adaptation to dry conditions?
A) broad leaves
B) many stomata
B) fleshy stems
D) creeping stems
Answer
660-10. Fungi that form mycorrhiza are obtained from the roots of plants
A) water
B) antibiotics
B) mineral salts
D) organic matter
Answer
660-11. The role of the stem in plant life is
A) strengthening the plant in the soil
B) the formation of organic substances
B) the movement of substances through the plant
D) absorption of water and mineral salts
Tissues form the organs of higher plants. Plants are very diverse: from a small duckweed floating on the water, various herbaceous plants (wheat, clover, ranunculus, bracken), shrubs (raspberry, wild rose, hawthorn, lilac) to tall trees (pine, birch, maple, oak, poplar ).
Plants have different life forms that provide adaptation to the conditions of existence. And they all consist of the same organs: they have roots and shoots and organs, thanks to which their sexual and asexual reproduction occurs.
Sexual reproduction occurs with the participation of gametes - germ cells: male (sperm or sperm) and female (eggs). Asexual reproduction is carried out with the help of a single cell - a spore, from which a new organism grows. All organs are divided into vegetative and generative.
Vegetative organs consist of roots and shoots and perform the function of growth, nutrition, metabolism. Vegetative organs do not participate in sexual reproduction and yet can reproduce in the so-called vegetative way (for example, using rhizomes, tubers, bulbs, mustaches, etc.). With this method, a new organism grows from the multicellular part of the parent individual.
The main functions of the root are the absorption of solutions of mineral substances, their conduction in the aerial parts and the fixation of plants in the soil. The leaf (lateral part of the shoot) carries out photosynthesis, gas exchange and water evaporation. The stem (axial part of the shoot) provides a connection between all parts of the plant, increases the surface of the aerial part, forms and arranges leaves and flowers in a certain way. In addition to the main ones, the vegetative organs perform additional functions.
Generative organs provide sexual reproduction. The generative organs of angiosperms are flowers, which form fruits with seeds. Sexual reproduction of flowering plants occurs during the flowering period (i.e. when the flowers open). The shape, size, color and structural features of the flower are very diverse. However, the main points in the structure and development of a flower are the same for all plants.
The flowers have stamens, pistils and a perianth that surrounds them. The main function of the stamens is the formation of pollen grains, which contain male germ cells. Seed germs are located in the pistil, they contain female reproductive cells. After fertilization, a seed arises from the seed germ, inside which there is an embryo and endosperm under the skin.
Surrounded by the seed of the pericarp, formed from the walls of the ovary. Together, the seed and the fruit form the fruit. After a dormant period, a young plant develops from the seed under favorable conditions. The generative organs of many other plants (for example, mosses, horsetails, ferns) have a different structure.
Vegetative organs of flowering plants. Vegetative organs in plants are those that serve to maintain individual life. In flowering plants, these are roots and shoot (which consists of a stem, buds, leaves).
Root- this is an axial, radially symmetrical underground plant organ. The main functions of the root are fixing plants in the soil and providing them with solutions of mineral substances (ground nutrition). The movement of solutions through plants in an upward direction is ensured by the active injection of solutions into the vessels by living root cells (the so-called root pressure). The root of plants arose as an adaptation to life on land.
In higher spore plants, the roots are only additional (arise on any part of the plant, except for the root); in gymnosperms, the main root is developed (it arises from the seed and is always one). Lateral roots branch off from the main and additional roots.
Angiosperms can have all three types of roots. The totality of the roots of a plant forms the root system. In shape, it can be rod and fibrous. The core system has a well-developed main root, which differs from other roots (dandelion, apple, burdock). If the main root is absent or poorly developed and inconspicuous among additional roots, then such a root system is called fibrous (in wheat, rye, corn, plantain).
The root, in addition to the main functions, can perform additional ones: it accumulates spare substances in cells, synthesizes compounds vital for the plant (amino acids, hormones, vitamins, etc.). The root can perform additional functions, acquiring certain new structural features, called modifications of the root.
Root crop- a complex formation: reserve nutrients are deposited in the main root and the basis of the shoot, it thickens (carrots, beets, parsley, radish). Root tubers are formed when reserve nutrients are deposited in additional lateral roots, which acquire tuberous forms (dahlia, sweet potato, spring millet).
Respiratory roots are found in some swamp plants to provide respiration to the underground part of the plant. These are lateral roots that grow upward and rise above the surface of the soil (or water). Supporting roots - adventitious roots that form on the stem: hanging roots of ficus bengal; stilted roots for additional support in corn; board-like roots of rubber ficus; nagging roots along the stem of climbing plants (in ivy).
