Read all about scale lichens 5kl. Lichens general characteristics and significance

Lichens are a truly special group of organisms. Despite the fact that they cannot be fully attributed to any kingdom of living organisms, in separate kingdom they are not singled out. The fact is that each lichen is a close symbiosis of two or three different types organisms.

Most often, a lichen is formed by a symbiosis of a fungus and unicellular algae. However, there are lichens formed by a fungus and cyanobacteria (blue-green algae). Cyanobacteria, although they are called blue-green algae, are classified as bacteria, and real algae are classified as plants. In addition, there are lichens formed by three species: fungus, algae and cyanobacteria.

Total lichen species are not that big. About 25,000 species.

The internal structure of the lichen body is different. Algae cells can be found randomly between fungal hyphae. But most often in the body of a lichen, separate layers can be distinguished. Above and below it is covered with a crust formed by a fungus. From below, this crust has special outgrowths for attaching to the surface. Under the top layer of the crust are algae cells. They need to be close to the surface to get the sunlight they need for photosynthesis. Below them are plexuses of hyphae of the fungus, forming the bulk of the body of the lichen.

External structure lichens are also different. According to the shape of the body, three groups of lichens are distinguished: scale, leafy and bushy. The name of these groups reflects what lichens look like. Scales look like a crust or scale on stones, trees, earth, etc. They are tightly attached to what they grow on. Leafy ones, respectively, look like bunches of leaves, and bushy ones look like bushes.

So what is the meaning of the cohabitation of algae and fungus in lichen? Algae, like a plant, is capable of photosynthesis. It forms organic matter. The fungus is not capable of photosynthesis. He needs ready-made organic substances for nutrition. And he takes them from algae cells. To do this, he braids them with his hyphae or even penetrates inside. But what is the use of algae? The fungus protects it from drying out, supplies water and minerals. After all, photosynthesis is impossible without water. And since lichens often live in cold climates (such as the tundra), where water usually turns to ice and algae is not available, cohabitation with the fungus is important for its survival in these conditions.

Since the mass of algae cells is much less than the mass of the fungus in the lichen, it cannot provide itself and the fungus with a large amount of organic matter. In addition, photosynthesis in lichen is less efficient than in ordinary plants. As a result, the lichen grows very slowly. On average, a few millimeters per year.
In a harsh climate, where plants cannot grow, lichens serve as food for herbivores. Otherwise, herbivores would not be able to live there. And then there would be no predatory animals there.

Lichens, unlike land plants, can grow on stones and rocks, tree trunks. They don't need soil. The fact is that they absorb water and minerals with the whole body, and not with roots, which they do not have at all. Lichen absorbs water like a sponge. Water is absorbed during rains, from air, dew, fog. If there are chemical pollution in the air, then the lichen will be poisoned. Therefore, lichens almost do not grow in cities, since the air is often dirty there.

Department of Lichens

Department of lichens occupy special place in flora. Lichens are very hardy plants. They grow in the most barren places. They can be found on bare rocks, high in the mountains, where other plants do not live. Lichens grow very slowly. For example, "reindeer moss" (moss moss) grows by only 1-3 mm per year. Lichens live up to 50 years, and some up to 100 years

general characteristics

a) special organisms resulting from the mutualism of fungi and algae (often including bacteria and cyanobacteria) consist of autotrophic and heterotrophic components

b) number of species - 26,000

c) habitat - different (soil, other plants, surface of stones, metal, glass, etc.)

Structure, reproduction, representatives, meaning

The thallus is formed by the interweaving of fungal hyphae with algae cells (green and blue-green).

Lichens live on rocks, trees, soil, both in the North and in tropical countries. Different types of lichens have different colors - from gray, yellowish, greenish to brown and black. Currently, more than 20,000 species of lichens are known. Lichens are studied by a science called lichenology (from the Greek "leuchen" - lichen and "logos" - science).

By morphological features(appearance) lichens are divided into three groups.

1. Scale, or crust, attached to the substrate very tightly, forming a crust. This group makes up about 80% of all lichens.

2. Leafy, which is a plate similar to a leaf plate, weakly attached to the substrate.

3. Bushy, which are free small bushes.

Lichens reproduce vegetatively, by pieces of the thallus, as well as by special groups of cells that appear inside their body. These groups of cells are formed in multitudes. The body of a lichen is torn under the pressure of their overgrown mass, and groups of cells are carried by wind and rain streams.

Lichens serve as food for domestic animals, for example, Yagel (Cladonia) and Icelandic moss are the traditional food of reindeer.

For a long time, lichens have been used as a remedy. It is known that Lobaria pulmonaria was used in the Middle Ages against pulmonary diseases, and lichens grown on the skull of a dead man against epilepsy. Icelandic cetraria (Cetraria islandica) is added to cough medicines, the antibiotic usnic acid was found in Usnea, used to treat skin and other diseases.

Lichen Usnea filipendula grows only in places with very high air quality. Lichens are indicator organisms (bioindicators) for determining environmental conditions, in particular air quality (lichen indication).

Due to the fact that lichens live for a long time and grow at a constant rate, they can be used to determine the age of the rock (glacier retreat or the time a new building was built) (lichenometry). Most often, yellow lichens of the genus Rhizocarpon are used for this purpose. This method, however, is not always accurate due to the disproportionate growth of the lichen and is not certain, and therefore should only be used when radiocarbon dating cannot be used.

For a long time, a valuable purple dye was obtained from lichens of the littoral genus Roccella and the species Pertusaria corallina. Carl Linnaeus mentioned in his "Plantae tinctoriae" ("Coloring Plants") six dye lichens. The dye and chemical indicator litmus is also obtained by extraction from Roccella. Evernia and Parmelia are used in Scotland and Scandinavia for dyeing wool and textiles. Particularly pleasant yellow and brown tones can be achieved. Also interesting is the use of the lichen Xanthoparmelia camtschadalis (an incorrect but often used synonym - Parmelia vagans) by the inhabitants of the Lower Volga region for dyeing Easter eggs.

Lichens can be found almost everywhere, even in Antarctica. This group of living organisms for a long time for scientists was a mystery, even now there is no consensus about their systematic position. Some believe that they should be attributed to the plant kingdom, while others - fungi. Next, we consider the types of lichens, the features of their structure, their significance in nature and for humans.

General characteristics of lichens

Lichens are the lowest group of organisms that consist of a fungus and algae that are in symbiosis with each other. The first are most often representatives of phycomycetes, ascomycetes or basidiomycetes, and the second organism is green or blue-green algae. Between these two representatives of the living world there is a mutually beneficial cohabitation.

Lichens, regardless of variety, do not have a green color, most often they can be gray, brown, yellow, orange or even black. It depends on the pigments and also on the color of the lichen acids.

Distinctive features of lichens

This interesting group organisms have the following characteristics:

• The cohabitation of two organisms in a lichen is not accidental, it is due to historical development.
• Unlike plants or animals, this organism has a specific external and internal structure.
• The physiological processes occurring in the fungus and algae differ significantly from those in free-living organisms.
• Biochemical processes also have their own distinctive features: as a result of vital activity, secondary metabolic products are formed that are not characteristic of any group of living organisms.
• Special way of reproduction.
• Attitude to environmental factors.

All these features baffle scientists and do not allow to determine the permanent systematic position.

Lichen varieties

This group of organisms is often called the "pioneers" of land, since they can settle in completely lifeless places. There are three types of lichens:

1. Scale lichens. They got their name for the shape, similar to scale.
2. Leafy lichens. They look like one large leaf blade, hence the name.
3. fruticose lichens resemble a small bush.

Consider the features of each type in more detail.

Description of scale lichens

Almost 80% of all lichens are scale. In their form, they look like a crust or a thin film, firmly fused with the substrate. Depending on the habitat, scale lichens are divided into:

Because of its special appearance this group of lichens can be completely invisible and merge with environment. The structure of scale lichens is peculiar, so they are easy to distinguish from other species. But the internal structure is almost the same for everyone, but more on that later.

Territories of scale lichens

We have already considered why scale lichens got their name, but the question arises: are the habitats different? The answer can be given in the negative, because they can be found in almost every latitude. These organisms are amazingly able to adapt to absolutely any conditions.

Scale types of lichens are distributed throughout the planet. Depending on the substrate, one or another species predominates. For example, in the Arctic it is impossible to meet species that are common in the taiga, and vice versa. There is a binding to a certain type of soil: some lichens prefer clay, while others feel calm on bare rocks.

But among the wide variety of this group of organisms, you can find species that live almost everywhere.

Features of leafy lichens

The thallus of this species has the form of scales or plates of medium size, attached to the substrate with a bundle mushroom hyphae. The simplest thallus resembles a rounded leaf blade, which can reach a size of 10-20 cm in diameter. With this structure, the thallus is called monophilic. If there are several plates, then polyphilic.

A distinctive feature of this type of lichen is the difference in the structure and color of the lower and upper parts. There are nomadic forms.

"Bearded" lichens

This name was given to fruticose lichens for their thallus, consisting of branched filaments that grow together with the substrate and grow in different directions. The thallus resembles a hanging bush, there are also upright forms.

The sizes of the smallest representatives do not exceed a few millimeters, and the largest specimens reach 30-50 cm. In tundra conditions, lichens can develop attachment organs, with the help of which organisms protect themselves from separation from the substrate in strong winds.

The internal structure of lichens

Almost all types of lichens have the same internal structure. Anatomically, there are two types:

It should be noted that those lichens that belong to scale do not have a lower layer, and the hyphae of the core directly grow together with the substrate.

Nutritional features of lichens

In the process of nutrition, both organisms living in symbiosis take part. Fungal hyphae actively absorb water and minerals dissolved in it, and algae cells have chloroplasts, which means they synthesize organic substances as a result of photosynthesis.

We can say that hyphae play the role of the root system, extracting moisture, and algae act as leaves. Because for the most part lichens settle on lifeless substrates, then they absorb moisture with their entire surface, not only rainwater, but also fog and dew are suitable for these purposes.

For normal growth and vital activity, lichens, like plants, need nitrogen. If green algae are present as a phycobiont, then nitrogen compounds are extracted from solutions when the thallus is saturated with moisture. It is easier for lichens, which have blue-green algae, they are able to extract nitrogen from the air.

Lichen reproduction

Regardless of the variety, all lichens reproduce in the following ways:

Considering that these organisms grow very slowly, we can conclude that the process of reproduction is also quite long.

Ecological role of lichens

The significance of this group of organisms on the planet is quite large. They are directly involved in the process of soil formation. They are the very first to settle in lifeless places and enrich them for the growth of other species.

Lichens do not require a special substrate for life, they can cover a barren area, preparing it for plant life. This is due to the fact that in the process of life, lichens secrete special acids that contribute to the weathering of rocks, oxygen enrichment.

Settling on bare rocks, they feel absolutely comfortable there, gradually creating favorable conditions for other species. Some small animals are able to change their color to match the color of lichens, thus disguise themselves and use them to protect themselves from predators.

The value of lichens in the biosphere

Currently, more than 26 thousand species of lichens are known. They are distributed almost everywhere, but it is surprising that they can serve as an indicator of the purity of the air.

These organisms are quite sensitive to pollution, therefore, in big cities near roads, plants, lichens are almost never found. They simply do not survive there and die. It should be noted that scale lichens are the most resistant to poor environmental conditions.

Lichens are also directly involved in the circulation of substances in the biosphere. Since they belong to autoheterotrophic organisms, they easily accumulate energy. sunlight and create organic matter. Participate in the process of decomposition of organic matter.

Together with bacteria, fungi and algae, lichens create favorable conditions for higher plants and animals. Settling on trees, these symbiotic organisms cause practically no harm, since they do not penetrate deep into living tissues. In some ways, they can even be called defenders, because a plant covered with lichens is less attacked by pathogenic fungi, lichen acids inhibit the growth of wood-destroying fungi.

But there is also back side: if the lichens grow too much and cover almost the entire tree, then they close the lenticels, disrupting gas exchange. And for insect pests, this is a great refuge. For this reason, on fruit trees it is better to control the process of lichen growth and clean the wood.

The role of lichens for humans

The question of the role of lichens in human life cannot be omitted. There are several areas where they are widely used:

Lichens do not cause any harm to human economic activity.

Summing up all that has been said, we can say that such nondescript and amazing organisms exist next to us. Despite their small size, their benefits are enormous, and for all living organisms, including humans.

Kingdom Mushrooms

Mushrooms is a large and diverse group of organisms. They are able to form great amount spores that are easily carried by the wind. Among the fungi there are unicellular, but most - multicellular organisms. They are varied in structure and size. The peculiarity of mushrooms is determined by a combination of signs of both plants and animals. Like plants, fungi are immobile and constantly growing. Like plants, fungi are able to synthesize vitamins.

Structure of Mushrooms

General signs of mushrooms

Diversity and importance of mushrooms

Kingdom Lichens

Lichens are unique living beings. They are a symbiosis of fungus and algae. Their body is called the thallus. It consists of fungal hyphae and green algae cells.

The structure of lichens

The main signs of Lichens

Types of lichen thalli

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The source of information:

1. Biology in tables and diagrams. / Edition 2e, - St. Petersburg: 2004.

2. Biology. Plants. Bacteria. Mushrooms and lichens / V.P. Viktorov, A.I. Nikishov. -M.: VLADOS, 2012.-256s.

Lichens represent special group organisms consisting of two completely different species. One part of a lichen is green algae (belongs to plants) or blue-green algae (belongs to bacteria). The other part of a lichen is a fungus.

Lichens are studied by science lichenology which is considered a branch of botany.

There are more than 25 thousand species of lichens.

Lichens are unpretentious and therefore widespread. They can be found even in permafrost conditions or on bare rocks. They can grow on tree trunks and the ground. Lichens living in the tundra spread along the ground in a continuous carpet.

The color of lichens varies from yellow and gray to brown and black.

According to the shape of the thallus, three types of lichens are distinguished.

fruticose lichens connected to the surface on which they grow, only at their base. Bearded lichen grows in spruce forests where it hangs from the branches of trees. Reindeer moss (reindeer moss) grows on the soil. If you step on it in dry weather, you will hear a characteristic crack.

foliose lichens found on tree trunks. They look like records different colors and forms. So golden-yellow xanthoria grows on aspen. Leafy lichens are connected to the substrate by rhizoid-like outgrowths. They are easily removed from the surface.

scale lichens(crustal lichens) appear as brownish and greyish crusts on stones and rocks. They adhere tightly to the surface, as a result of which it is difficult to tear them off from it.

Lichens are most often considered an example of symbiosis, in which cohabitation is beneficial for two different organisms.

The body of a lichen is called thallus. It consists of fungal hyphae, between which are single-celled green algae or blue-green algae.

Such cohabitation allows lichens to live where neither fungi nor algae can live separately. The hyphae of the fungus provide the algae with water and minerals. Algae provides the fungus with organic substances that it synthesizes in the process of photosynthesis.

Since algae have to feed not only themselves, but also the fungus, lichens grow very slowly. Also, often, growing in places with permafrost, lichens do not receive enough water. So the growth of bushy lichens can be several millimeters per year, and scale - in general, fractions of a millimeter. However, lichens live long enough (up to 100 years).

Lichens reproduce asexually. Algae cells divide into two, and the fungus forms spores. Also, special groups of cells can form in the lichen thallus. These groups leave the parent lichen and give rise to a new organism in a new place.

The meaning of lichens

Lichens are the first to colonize places where there is no soil. Gradually dying off, they form humus. Also, lichens secrete acids, which leads to the destruction of rocks. As a result of mixing destroyed rocks and humus, soil is formed on which plants can grow.

Yagel serves as food for deer in the tundra. It is also used as pet food.

Icelandic moss is eaten by humans.

From a number of lichen species, litmus (a chemical indicator) and antibiotics are obtained.

Oak moss is used in perfumery. It gives strength to spirits.

Lichens are ecological indicators. They die in polluted air. Therefore, by the absence or presence of lichens in a certain area, one can judge the ecological situation.