Walking through the forest, on stones, snags, trees, you can notice relief outgrowths or "bushes" of different colors and shapes. This is what a lichen looks like. For a long time, he was a real mystery for doctors and nature researchers. Since ancient times, people have used lichens in medicine, eaten, dyed fabrics with their help. The science that studies lichens is called lichenology. This article covers general characteristics lichens as organisms.
Lichens belong to the kingdom of fungi, but scientists consider them as a separate unique group. There are many in nature, but at the moment about 25 thousand species have been discovered.
The body of the plant is called thallus, thallus, slate. The variety of its colors, shapes and sizes is amazing. The thallus can grow with a crust and a leaf-like plate, as well as a bush, tube or ball. The plant can be as tall as a human being, or it can measure from 3 to 7 cm.
Lichens grow incredibly slowly, scientists have discovered a specimen that is more than 4000 thousand years old.
All lichens are divided by lichenology into three groups, depending on the shape of the thallus. The first group - scale (crustal), looks like a crust, tightly attached to the surface of the place on which it grows. Representatives of this group are located on rocks and stones.
The second group, leafy, located on wood, soil and stones, are similar to plates and have wavy edges. They are firmly attached to the surface with a short, thick stem.
The third group, bushy, as you might guess from the name, look like a standing and hanging bush, branched or not. Such bushes grow on soil, to which they attach with the help of filamentous rhizoids. They also grow on tree branches, to which they attach with the help of several thallus sections.
According to the place of growth, lichens can be divided into epigeic (on the soil), epiphytic (on the trunks and branches of trees) and epilithic (on stones and rocks). These plants have a wide variety of colors.
The bark, which is a dense formation of mycelium hyphae, is covered with pores. With which the plant breathes. With the help of the bark, lichens also absorb moisture from the air and protect themselves from hypothermia and overheating.
Internal structure
Lichen is an organism composed of mycelium and algae (sometimes cyanobacteria). What are the structural features of lichens, you can find out by examining the plant under a microscope. Already at a magnification of 15 × 8, you can see in it how the threads of the mycelium entwine the algae cells.
Nutrition system and reproduction
Lichens are fed by the vital activity of both symbionts. The mycelium absorbs water and absorbs the nutrients it contains, while the algae (cyanobacteria) feeds on chlorophyll and photosynthesis. As mentioned above, algae are classified as autotrophic organisms, that is, they are capable of synthesizing organic substances from inorganic ones, and fungi are heterotrophic ones that do not have the possibility of photosynthesis or chemosynthesis. The fact that these two organisms exist side by side is a distinguishing feature of lichens as a species.
Lichen is a plant that reproduces vegetatively and sexually. During sexual reproduction, the plant forms spores, which, during germination, wait for a meeting with a suitable algae in order to form a new thallus with it.
For vegetative propagation, in some lichens, you can find special isidia that look like small shoots or twigs. They break off easily, a new thallus is formed from them. Some plants of this species form sredia that are easily carried by the wind. Sredie is an algae cell that is tightly intertwined with hyphae.
Spread
Lichen is a bioindicator organism. This definition is very suitable for this species. After all, they grow only in places with good environmental conditions. Therefore, in a city polluted with waste from cars and businesses, you will never find this plant. As soon as harmful impurities appear in the air, it dies.
The lichen can live in conditions where any other plant will not survive... Due to their bark, they absorb every water molecule from any available source: fog, dew, air. Their habitat can be the tundra, the tropics, swamps and even the desert. They are one of the few plants in Antarctica.
Role in nature and human life
Lichens are pioneers in colonizing the surfaces of bare rocks and stony soils. They promote the process of breaking down rocks with the acids they produce. After death, they take part in the process of soil formation, serve as food for various organisms. Lichens, located on the branches and trunks of trees, are an excellent defense against pest fungi that penetrate into the bark of a tree and destroy it from the inside.
Reindeer moss and reindeer moss are of great importance. During the winter months, these plants are the only food for the reindeer. The rest of the ungulates also pay attention to the multi-colored thalli. Yet, half of this plant is a fungus, which are known to be a source of proteins and vitamins.
Certain types serve as the basis for some dishes. For example, in Iceland, when bread is baked, lichen powder is added to the flour. In Japan, some lichens are considered a real treat.
IN Ancient egypt lichens were used to treat diseases, and in the 18th century they are mentioned in many official reference books of medicines. All this is due to the property of killing disease-causing organisms.
These unusual plants have found their place in the perfume industry to create unique fragrances. In the textile industry, they are used as natural dyes, and in the chemical and food industries, they are used as sources of alcohol and sugars.
- (Lichenes), organisms formed by the symbiosis of a fungus (mycobiont) and algae (phycobiont); traditionally belong to the lower plants. The early fossils of L. are presumably referred to the top. chalk. They occurred as a result of the transition of certain representatives ... ... Biological encyclopedic dictionary
Organisms that are a symbiosis of a fungus (mycobiont) and algae (phycobiont). In L., apparently, there is no strict selectivity between partners - a fungus can exist with different types of algae, and algae - with different fungi. ... ... Microbiology Dictionary
Lichens - LICENS, lichens, Lichenes, a peculiar class of lower plants, consisting of fungus and algae, forming together one organism. With few exceptions, lichen mushrooms are marsupials. L. algae bear the common old name of gonidia. Not… … Great medical encyclopedia
Polyphyletic group of mushrooms Ernst Heinrich Haeckel ... Wikipedia
- (Lichenes), a widespread group of symbiotic organisms that usually grow on stones or tree trunks, less often on soil and receive the moisture they need for life from the atmosphere. Several species inhabit the marine littoral zone (tide ... ... Collier's Encyclopedia
- (Lichenes) a specialized group of fungi that are in constant cohabitation with algae; some botanists regard L. as an independent group of lower plants. The science of L. is called lichenology (See Lichenology). ... ... Great Soviet Encyclopedia
lichens - ▲ lower plants lichens symbiotic organisms formed by fungi and algae. reindeer moss, reindeer moss. cladonia. tsetraria. | manna. sredii. | lichenology. obshesit. stunned. suede. mossy (# stump) ... Ideographic Dictionary of the Russian Language
lichens - kerpės statusas T sritis ekologija ir aplinkotyra apibrėžtis Organizmų grupė, kurių kūnas sudarytas iš grybo ir dumblio simbiozės. atitikmenys: angl. lichens vok. Flechten, f; Lichenen rus. lichens, m ... Ekologijos terminų aiškinamasis žodynas
Yageli, spore plant., Fungi and algae cohabit in the body. By assimilation, fungal and algal cells exchange nutrients: the former give water and minerals and receive organic from the latter ... ... Agricultural dictionary reference
Books
- Biology. Plants, bacteria, fungi and lichens. Grade 6, V.P. Viktorov, A.I. Nikishov. The textbook is written in accordance with the obligatory minimum of the content of biological education and the requirements for the level of training of students of the basic (basic) school. It contains the most essential ...
The lichen class is one of the most widespread and diverse organisms on Earth. Science knows more than 25 thousand of their species, the system of their distribution is still not fully understood. Their system is arranged of two elements: a mushroom and algae, it is this composition that unites a huge variety.
What are scale lichens
The name "lichens" comes from an analogy with lichen disease, which arises from their appearance. Lichens are representatives of a unique species, known to those, in their composition there are simultaneously two organisms at once, an alga and a fungus. Many scientists distinguish a separate class for this. Their combination is unique: the mushroom inside its body creates a special habitat in which the alga is protected from external influence and is provided with liquid and oxygen. The fungus consumes water from the substrate, absorbs oxygen, so the alga inside it gets nourishment and feels comfortable. For their existence, no special soil is required; they grow wherever there is air and water, even in minimal quantities. Representatives of crustose lichens cover bare rocks, stones, grow on clay, on roofs and trees.
Growing areas of crustose lichens
Lichens are one of the most abundant microorganisms on the planet. In almost every latitude, you can find crustaceans lichens that can adapt to any conditions. Adapted to cold weather, they feel good on the slopes of the polar cliffs, they are comfortable in the tropics and deserts.
Crustaceous lichens are common throughout the planet, they do not require unique specific conditions. Depending on the type of substrate and the characteristics of the climate, this or that species grows on the ground. Growing up, they cover huge areas, completely filling the slopes of the rocks and covering the stones.
Typically, groups are attached to climatic conditions or to the natural area. Some species can be found only in the Arctic, others only in the taiga. But this system has a number of exceptions, when the geography of growth is associated with environmental conditions that are repeated in different regions. These lichens live on the shores of freshwater lakes, oceans, mountains, etc. Also, the distribution can be tied to certain soil characteristics: some groups of lichens grow on clay, others on rocky soil, etc.
Significance for ecology
In the ecological system of the planet, they are found everywhere. The importance of lichens is great, these organisms perform a whole layer of work. They play an important role in the formation of the soil, they are the first to penetrate into the layers and enrich it for the further growth of other species. Scale lichens do not need a special substrate, covering the territory of barren soil, they enrich it and make it suitable for other plants to live. In the process of growth, they release special acids into the soil, thanks to which the earth becomes loose, weathering and enrichment with oxygen occurs.
The favorite growing environment for crustose lichens, where they feel comfortable, is rocks. They confidently attach to rocks and cliffs, change their color, gradually creating conditions on their surface for the development of other species.
Many animals have a color corresponding to one or another type of lichen that grows in their habitat. This allows you to camouflage and protect yourself from predators.
External structure
The appearance of these symbiotic mushrooms is extremely diverse. Lichens, scale or crust, are so called because they create a crust resembling scale on the surface where they grow. They can take many forms and have unexpected colors: pink, blue, gray, lilac, orange, yellow, or another.
Scientists distinguish between 3 main groups:
Scale;
Leafy;
Bushy.
Typical signs of lichens are crustaceans - they firmly adhere to the ground or other substrate, it is impossible to remove them without damage. Such lichens are most common in cities, where they can grow on concrete walls and trees. They can also often be found on the slopes. Wherever these lichens are found, their scale varieties do not require any essential conditions and feel great even on stones.
They are a crust that covers surfaces unsuitable for the life of other plants. Due to the peculiarities of their structure and appearance, they can be imperfectly invisible and merge with nature. Mistakenly, all such mushrooms are just one of the thousands of lower plant varieties.
It is very easy to distinguish crustal lichens from other species. The leafy ones are attached to the soil with sprouts that resemble small stems. The body of the lichen itself has a leaf-like appearance of various shapes, their sizes can also vary.
Bushy have the most complex external shape. They consist of twigs, round or flat, can grow on the ground, rocks. They are the largest, growing and can also hang from trees.
Crustaceous lichens can have a transitional position between these groups and features of other species: this classification is focused solely on their external features.
Internal structure
The body of the lichen crust, or thallus (thallus), is of two types:
Homeomeric;
Heteromeric.
The first type is the simplest, in which algae cells are kept in a chaotic manner and are distributed fairly evenly between the fungal hyphae. Most often, such a structure can be found in a slimy lichen, for example, in crustose lichens of the genus Collema. In a calm state, they look like dried crusts, and under the influence of moisture they instantly swell, taking on the appearance You can meet them on the Black Sea coast.
The heteromeric lichen thallus has a more complex structure. Most crustaceans are of this type. In the context of this type, its structured internal organization can be traced. The top layer is formed by a fungus, thus protecting the algae from drying out or overheating. Below, the mushroom has branches that attach to the algae cells. Below there is another layer of the neck, which is a substrate for algae, with its help the required level of moisture and oxygen is maintained.
Lichen groups
According to the type of growth and attachment to the type of substrate, the following groups are distinguished among crustose lichens:
Epigeic;
Epiphytic;
Epiletic;
The first group, epigeic lichens, is distributed on various soils; they also grow well on stumps and rocks. They can well withstand competition with plants of higher groups, therefore, they rarely grow on scarce soils, preferring fertile land. Some of them grow in dry swamps, along roads, in the tundra, where they occupy vast territories, etc. The most famous species are the lyceum, pertusaria, ikmadofida.
Epigeic lichens can also be divided into two more categories: moving lichens (refer to other species) and lichens fixed on the soil, which are mostly scaled. Attached scale deposits can exist on sandy, limestone, and clayey soil. The names of crusty lichens in this group are as follows: rolled ramaline, dark brown parmelia, collema, pink beomycez and others.
Epiphytic lichens grow exclusively on trees or shrubs. They are conventionally also divided into two groups: epiphilic (exist on leaves, bark) and epixil, arising on fresh sections. In most cases, they are found precisely on the bark; on a tiny area, a couple of dozen different types of scale lichens can coexist at the same time, completely changing the color of the tree and creating a new outer surface.
The epilithic group of crustose lichens settle on rocks and stony rocks. Examples of them are diverse: some start exclusively on limestones, others prefer flint rocks, and still others settle here and there, as well as on city roofs and walls.
Types of scale lichens
Crustaceous lichens are of all four types accepted in science: epilithic, epigeic, epiphytic, and epixelic. They can grow on tree trunks, dead wood, or tree stumps, but most often they grow on bare rocks.
Lichens grow on a variety of substrates. Examples can be easily found in any city or forest: on walls, roofs, stones, rocks. They grow so tightly to the soil that it is impossible to remove them without damage.
Lichens form a scum-like crust. They can have a very different color, and, completely covering the subject of the landscape, significantly change its appearance. Pink rocks, purple, make the landscapes bright and unusual.
Aspicilia, hematoma, lecanor, lecidea, graphis, biator are the most famous scale lichens, examples of their growth are found almost throughout the country. The biator variety can exist simultaneously on swamps and on rocks. Lecanor scale lichen, for example, can grow on various substrates: both on stones and on trees or stumps.
Reproduction of scale lichens
There are three ways of reproduction: vegetative, sexual or asexual. Sexual reproduction is one of the most common ways: lichens form apothecia, perithecia or gastrothecia - these are different bodies within the body in which spores develop. Their development is extremely slow and can last up to 10 years. After this process is completed, gastrothetia begin to produce spores, which subsequently germinate at the desired temperature and humidity.
With asexual sporulation of lichens, spores arise and develop right on the surface.
In vegetative reproduction, tiny substances consisting of particles of algae and fungus and thallus bushes are involved. They spread with the wind or animals, traveling until they find a suitable substrate. It is the fastest breeding method and spreads quickly. Reproduction in this way can also occur with an unprepared piece of lichen, but in this case, the chances of growing on a new substrate will be lower.
Application
The use of scale lichens is unusually wide: they are able to grow where there is no chance for any other plant. Over time, they prepare the necessary environment, a sufficient amount of humus for the growth of other plants. At the same time, of the entire multi-thousand variety of lichens, only two species are poisonous, the rest find their application in different areas: agriculture, medicine.
The use and significance of lichens in pharmacology is also great: healers in villages know beneficial features each of hundreds of species, using them to treat the widest range of diseases: from coughs to oncology. Lichens are especially effective in the treatment of purulent inflammations. They are carefully cut from the surface and applied to the wound - thanks to their antibacterial properties and antiseptics, they destroy bacteria, help cleanse and heal an open wound.
Environmental measurement with lichens
They are also used in science to study environmental conditions and air quality. Scale lichens are the most resistant to deterioration of natural conditions, they endure environmental disasters and high levels of air pollution, but this significantly affects their condition. Due to the peculiarities of their structure, lichens absorb the incoming water and air without additional filters, all at once with the thallus. Because of this, they are sensitive to pollution and changes in the composition of air or water, since toxins instantly disrupt their internal work.
Due to the increased content of toxic substances in the atmosphere or water, cases occur mass death scale lichens. The first such cases began to occur near large industrial cities, where production is developed, and, consequently, a high level of air pollution. These cases clearly demonstrated the need to filter emissions of harmful substances into the air. Today lichens are growing again in large cities thanks to environmental care and improved air quality.
There are two directions for studying the state of air according to the state of representatives of this species: active and passive. With a passive one, conclusions are drawn about the state of the atmosphere here and now, an active one means a long study of a certain type of lichen, which makes it possible to get a more accurate picture.
Lichens and their difference from other plants
Lichens represent a peculiar group of complex organisms, the body of which always consists of two components - fungus and algae. Now every schoolchild knows that the biology of lichens is based on the phenomenon of symbiosis - the cohabitation of two different organisms. But a little more than a hundred years ago lichens were a great mystery to scientists, and the discovery of their essence by Simon Schwendener in 1867 was regarded as one of the most amazing discoveries of that time.
However, as organisms, lichens were known to scientists and among the people long before the discovery of their essence. Even the great Theophrastus (371-286 BC), "the father of botany", gave a description of two lichens - sleep (Usnea) and rocella (Roccella). The latter was already used then to obtain dyes. Gradually, the number of known lichen species increased. True, in those days they were often called mosses, now algae, sometimes even "chaos of nature" and "poor poverty of vegetation."
More than 20,000 lichens are now known. And every year scientists discover and describe dozens and hundreds of new unknown species.
Currently lichenology (lat. lichen - lichen) - the science of lichens - studies a complex set of problems associated with the origin, phylogeny, structure, taxonomy, biochemistry, physiology, distribution and ecology of lichens. These issues will be discussed below.
How are lichens different from other plants?
First, a specific feature of lichens is the symbiotic cohabitation of two different organisms - a heterotrophic fungus (mycobiont) and an autotrophic alga (phycobiont). Not all cohabitation of fungus and algae forms lichen. Lichen cohabitation should be permanent and historically developed, and not accidental, short-term. In nature, there are cases when a fungus and algae form a temporary mixed accumulation, but this is not a lichen yet. In a real lichen, the fungus and algae enter into a close relationship, the fungal component surrounds the algae and can even penetrate their cells.
Secondly, lichens form special morphological types, life forms that are not found separately in fungi and algae that make up the lichen thallus, i.e. lichens have gone through a historical, long-term form-forming process based on symbiosis, which led to the formation of specific morphological forms of the external and internal structure ...
Thirdly, lichens as a whole and each of their components separately are characterized by a special type of metabolism. The physiology of fungi and algae in the lichen thallus differs in many respects from the physiology of free-living fungi and algae.
Fourthly, the biochemistry of lichens is very specific, the formation of secondary metabolic products in them - lichen substances that are not found in other groups of organisms.
Finally, lichens differ significantly from other groups of organisms, including free-living fungi and algae, by a special biology: methods of reproduction, slow growth, attitude to environmental conditions, etc.
Based on these specific properties, lichens can be defined as follows: lichens are organisms whose body (thallus) constantly consists of two components - an autotrophic phycobiont and a heterotrophic mycobiont, which form a single symbiotic cohabitation, characterized by special morphological types and special physiological and biochemical processes.
However, it should immediately be noted that all plants belonging to lichens are divided into three unequal groups, of which it is quite consistent this definition only the first of them, including, however, the vast majority of known species. This group of species is distinguished as a class of marsupial lichens, since the fungi that formed them are marsupial mushrooms. The second very small group is distinguished as a class of basidial lichens in accordance with the fact that they are formed by basidiomycetes. Basidial lichens are a less resistant group and do not correspond to all of the indicated characteristics. Finally, among lichens, there is a third group of species in which the fruit bodies are so. spores have not been found, so their place in the lichen system remains unknown. They are combined into an artificial group "Imperfect lichens" (Lichenes imperfecti). Over time, some of them find ascocarps and then they are transferred to the appropriate place in the system of the class of marsupial lichens. In other cases, other data can indicate the actual place in the system - the fine structure of the thallus or chemism. Of the imperfect lichens, the most common are the so-called lepraria (Lepraria). They form powdery deposits on various substrates - stones, rocks, tree trunks, mosses, usually whitish-gray (Lepraria aeruginosa), sometimes greenish-yellow (Lepraria chlorina) or intense yellow (Lepraria candelaria).
In this book, only the first two classes are considered; we do not dwell on imperfect lichens further.
Plant life: in 6 volumes. - M .: Education. Edited by A. L. Takhtadzhyan, Editor-in-Chief Corresponding Member USSR Academy of Sciences, prof. A.A. Fedorov. 1974 .
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These amazing plants are an example of mutually beneficial coexistence of fungi and algae, less often - fungi and cyanobacteria. It even happens that the three cohabit: mushrooms (required) and algae + cyanobacteria. Such cohabitation is called obligate symbiosis.
Lichen species for different characteristics
There are two-component lichens and three-component lichens. Depending on the number of components in them.
Behind appearance thallus (thallus) lichens can be divided into the following groups:
- scale lichens. The smallest and longest-lived, they grow mainly on stones, rocks, concrete walls, trees, old fences. It is difficult to separate them from the object on which they grow;
- leafy lichens - these associates can no longer attach themselves to the substrate with the whole body, but only by one edge (outgrowths - rhizoids), are easily separated, look like a leaf. They grow on stones, stumps, long-lying objects such as rusty iron, glass, slate;
- bushy lichens most developed. They grow upward (unlike the first two) and have a bushy appearance. They are attached mainly to the ground or trees. They are in the form of twigs or threads. They can grow up to 6 - 7 meters.
Behind internal structure, this symbiosis can be grouped like this:
- heteromeric - the body of the lichen on the cut is clearly divided into layers of fungus and algae;
- homeomeric - the components are randomly mixed inside the thallus.
For the place of growth, lichens are divided:
- epigeic (grow on the ground);
- epilithic (grow on stones);
- epiphytic (grow on tree trunks).
Mutual benefits of fungi and algae
So why should mushrooms and algae live together, in one body? And here's why: algae need water (moisture) for normal life, and a mushroom needs ready-made food - it will not cook anything for itself from water and light (as almost all plants do), therefore it - a heterotroph - feeds on the products of algal photosynthesis ( autotrophs), to which it provides moisture. He accumulates it in himself like a sponge.
Where lichens grow
Probably everyone knows that lichens are the pioneers of the area. Often, in not yet inhabited territories, due to some circumstances (fires, land reclamation, volcanic eruptions, drainage of territories), lichens appear first. Moreover, they serve as an excellent fertilizer and food for other organisms.
These plants can survive in extreme conditions. Their scale ranges from -47 degrees Celsius to plus 80 ºC. They can withstand acidic, alkaline, and even strong ultraviolet radiation. Which is not typical for other plants. The growing area is also large: from the far north to Antarctica.
The role of lichens in the life of animals and humans
Although these organisms are inconspicuous, their significance is important for other living beings, in particular for the inhabitants of the northern territories. In the harsh Siberian winters, lichens Yagel or deer moss, Icelandic moss are the main food for deer, and moose and roe deer look for them under the snow. Many birds use it as bedding in nests.
There are also edible lichens for humans. This is Fremont's briory, edible aspicilia. They are especially loved in China and Japan. For medicinal purposes, they use Icelandic tsetraria, Lobaria. For the manufacture of dyes, indicator "litmus", odor fixer, in perfumery - lichens are used everywhere.
Thus, it is difficult to exaggerate the importance of such a small and inconspicuous lichen for biocenosis and food chains. Its only drawback is its growth on sculptures and monuments, which a person has to get rid of, but these are purely human problems, the rest of the living world is not a problem.