Plants of the department "Gymnosperms": signs, structural features, examples
Plants play a very important role in nature, sohow they are capable of photosynthesis. This process, as a result of which a plant from carbon dioxide, water and solar energy receives nutrients for itself and releases oxygen into the atmosphere. Therefore, it is because of the plants on Earth that there can be animals and we are with you.
Classification of plants
The whole kingdom of plants is divided into ten divisions:
- Brown seaweed.
- Green algae.
- Blue-green algae.
- Red algae.
- Plain shaped.
Among these plants, depending on the complexity of the structure, two groups can be distinguished:
- the lowest;
The lower all the algae parts are, because they do not have differentiation of tissues. The body does not have organs. It is called the thallus.
Higher plants, depending on the method of reproduction, can be divided into:
Spores include fern-shaped, moss-shaped, moss-like, horsetail.
Seeds are classified as gymnosperms and angiosperms.
We will talk more about the gymnosperms in this article.
Classification of gymnosperms
The next taxon that stands out in all departments of the kingdom of "Plants" is a class. Gymnosperms are divided into four classes:
- Cycadic (Cycadal).
About the representatives and features of each class, we'll talk later. And now the common features of all gymnosperms, their physiology and biology will be examined.
Gymnosperms: the structure of the plant
This department belongs to higher plants. This means that their body consists of organs that are constructed from different types of tissues.
Organs of gymnosperms
Depending on the location of the organs, they can be divided into underground and terrestrial. Given their functions and structure, it is possible to identify vegetative and generative organs.
Vegetative organs: structure and function
This group of organs includes the underground root system and ground escape.
The root system consists of many roots, among which one main and many lateral roots can be distinguished. In addition, the plant may have additional roots.
The root has such functions:
- Fastening the plant in the soil.
- Absorption of water with micro- and macro elements dissolved in it.
- Transportation of water and dissolved minerals to terrestrial organs.
- Sometimes - the storage of nutrients.
Escape is also a system of organs. It consists of a stem, leaves and kidneys.
Functions of the organs of escape:
- Stem: support and transport functions, providing a link between the roots and leaves.
- Leaves: photosynthesis, breathing, gas exchange, temperature regulation.
- Kidney: from them new shoots are formed.
Gymnosperms and angiosperms have identical vegetative organs, but their generative organs are different.
Generative organs of gymnosperms
Generative organs are those thatensure the reproduction of the body. In angiosperms it is a flower. But the plants of the department "Gymnosperms" in the majority have such generative organs as cones. The most vivid examples are fir and pine cones.
It is a modified shoot, covered with scales. There are male and female cones in which male and female sex cells (gametes) are formed, respectively.
Male and female pine cones as an example can be seen in the photo below.
There are representatives of gymnosperms,which both male and female plants are on the same plant. They are called monoecious. Also there are dioecious gymnosperms. They have male and female cones are in different forms. However, the plants of the department "Gymnosperms" are mostly monoecious.
On the scales of female cones there are two ovules, on which female gametes are formed - oocytes.
On scales of male cones are pollen sacs. They form pollen, which contains sperm - male sex cells.
When we have already considered the structure of gymnosperms, let's talk about their reproduction.
How pine grows from cones
Reproduction of gymnosperms occurs with the help of seeds. They, unlike the seeds of flowering plants, are not surrounded by fruit.
Reproduction of gymnosperms begins with the fact thatplants in a certain period from the kidneys are formed modified shoots - male and female bumps. Further on, they form pollen and ovules, respectively.
Pollination of female cones occurs with the help of wind.
After fertilization of the ovules, which are located on the scales of female cones, the seeds develop. Of these, new representatives of gymnosperms are then formed.
What tissues are the organs?
The plants of the "Gymnosperms" department, like all the higher ones, consist of different tissues.
There are such types of plant tissues:
- Coverslips. These tissues perform a protective function. They are divided into epidermis, cork and crust. The epidermis covers all parts of the plant. It has stomata for gas exchange. Also, it can be covered with an additional protective layer of wax. Cork is formed on the trunk, roots, branches and kidney scales. Cork is a cover tissue, consisting of dead cells with stiffened membranes. The core of the gymnosperms consists of it.
- Mechanical. This fabric provides the strength of the stem. It is divided into a collenchyma and a sclerenchyma. The first is represented by living cells with thickened membranes. Sclerenchyma also consists of dead cells with stiffened membranes. Mechanical fibers are part of the conductive tissues contained in the stems of gymnosperms.
- The main fabric. It is the basis of all organs. The most important type of basic tissue is assimilation. It forms the basis of the leaves. In the cells of this tissue there is a large number of chloroplasts. Here, photosynthesis takes place. Also in the organs of gymnosperms there is such a kind of underlying tissue as a storing one. It collects nutrients, resins, and the like.
- Conductive tissue. It is divided into xylem and phloem. Xylem is also called wood, and phloem is called a bast. They are in the trunk and branches of the plant. Xylem of the gymnosperms consists of vessels. It provides transportation of water with dissolved substances in it from the root to the leaves. The phloem of the gymnosperms is represented by the sieve tubes. Lub is intended for the transport of substances from the leaves to the root.
- Educational fabrics. Of these, all other tissues of the gymnosperms are formed, from which all organs are then constructed. They are divided into apical, lateral and intercalary. The apical are located on the top of the shoot, and also on the tip of the root. Lateral educational tissues are also called cambium. It is in the trunk of the tree between the wood and the bast. Inserted educational fabrics are at the base of internodes. There are also wound educational tissues that arise at the site of damage.
So we examined the structure of gymnosperms. Now let's move on to their representatives.
When we already know how plants of this department are arranged, let's consider their diversity. Next, representatives of various classes who are members of the "Gymnosperms" department will be described.
The plants of the "Gymnosperms" department of the "Gnetovye" class are divided into three families
- Family "Velvichievye."
- Family "Gnetovye".
- Family "Chyvoynikovye".
Let's look at the brightest representatives of these three groups of plants.
So, velvichia is amazing.This is the only member of the familyof welwich. This representative gymnosperm grows in the Namib Desert, as well as in other deserts of South West Africa. The plant has a short but thick trunk. Its height is up to 0.5 m, and the diameter reaches 1.2 m. Since this species lives in the desert, it has a long main root, which goes 3 m deep. The leaves that grow from the barrel of Velvichie are a real miracle. Unlike the leaves of all other plants on Earth, they never fall off. They constantly grow at the base, but periodically die off at the ends. Constantly updated in this way, these leaves live as much as the Velvichia itself (known specimens that have lived more than 2 thousand years).
The familial family contains about 40 species. This is mainly shrubs, lianas, less often - trees. They grow in the tropical forests of Asia, Oceania, Central Africa. Their kind of umbrella resembles more angiosperms. Examples of representatives of this family are melinjo, gnetum broadleaf, gnetum ribbed, etc.
The family of conifers includes 67 speciesplants. In terms of life form it is shrubs and semishrubs. They grow in Asia, the Mediterranean and South America. Representatives of this family have scaly leaves. Examples of conifers include the American ephedra, concha horsetail, coniferous coniferous, conifers green, etc.
This group includes one family. The only representative of this family is ginkgo bilobate. This is a tall tree (up to 30 meters) with large fan-like leaves. This relict plant, which appeared on Earth 125 million years ago! Extracts from ginkgo are often used in medicine for the treatment of vascular diseases, including atherosclerosis.
This is also gymnosperm. Examples of plants of this class are the Rumpha pendulum, the cycling drooping, the crook of the Toar, etc. They all refer to the same family - "Cyclonic".
They grow in Asia, Indonesia, Australia, Oceania, Madagascar.
These plants look like palms. Their height is from 2 to 15 meters. The trunk is usually thick and short, when compared with thickness. So, the cycad's drooping figure reaches 100 cm, while the height is 300 cm.
This is perhaps the most famous class of the gymnosperm plant. He is also the most numerous.
This class consists of the same order - "Pine". Earlier on Earth, there were three more orders of the conifer class, but their representatives were extinct.
The above order consists of seven families:
The family of cephalothorax consists of 20representatives. These are evergreen shrubs and trees. The needles are spirally oriented. From the yew, the head capitate is distinguished by the fact that their cones take longer to ripen, and they also have larger seeds.
The yew family includes about 30 speciesshrubs and trees. All plants of this family are dioecious. Examples of representatives of this family include Pacific yew, Florida, Canadian, European yew, etc.
The family of cispidopitides includes evergreen trees, which are often used as ornamental trees.
Examples of representatives of the Podokarpov family include dacridium, phylloclus, podkarp, etc. They grow in wet locations: in New Zealand and New Caledonia.
The family of araucariae includes about 40 species. Representatives of this family existed on Earth already during the Jurassic and Cretaceous periods. Examples are southern agate, agamis dammara, brazilian araucaria, Chilean araucaria, noble wolmia, etc.
The family of pine includes such allknown trees, like spruce, pine, cedar, larch, zug, fir, etc. All plants belonging to this family grow in the Northern Hemisphere in a temperate climate. Gymnosperm plants of this family are often used by man in medicine and other industries thanks to their resins and essential oils.