Lichens - Amazing living formations that are put in the deadlock of adherents of strict biological systematics. Indeed, to what a taxon to attribute organisms, which, as if as a result of the experiment of a nutty scientist, are the union mushrooms (also "hung" between plants and animals) with algae or cyanobacteria? Gifs of the fungus create the basis of the body of the lichen, the internally filling is the cells of algae. Thanks to them, more precisely, their ability to photosynthesis, this strange organism gets energy to produce nutrients.

Petrified lichens are a rare find because of their vulnerability to their bodies, reliable include Devonian lichens with age at about 400 million years. Now the group has about 25 thousand species. Lichens is extremely unpretentious, without losses tolerate cold wet climate, but also the heat with drought.

So, what are characteristic features of lichens?

Where do lichens live?

You can meet lichens not only in the forests and mountains of Asia, Europe and both Americas, but even in Antarctica and the Arctic. They are comfortable in huge temperature limits: from -50 to +60 degrees. Photosynthesis does not stop even in the frost! Lichenss are capable of living on bare stones, pleaseing with a small amount of nutrients. On glass, fabrics and metal - lichens also live!

For their nutrition, everything is suitable: droplets of moisture from fog, dew, dust particles. True, lichens is extremely sensitive to polluted air - the excess of harmful substances are ruined.

Survive in difficult environments sheets Types of lichens help ricoidaSometimes equipped with special plates or mucus drops for better attachment to the base.

Lichens structure and nutrition

1. Lichen wall Golden (The genus Xantorio) probably saw many - he lives on the trunks of trees, on the stones, representing a totality of tiny bright yellow funnels. This Xantoria is referred to heteromeric Lichens, that is, those whose body is quite clearly divided into several layers. If you make a thin section of xanutsia, the woven gifs of mushrooms are visible in the upper and lower parts (crusts). The lower gifs attach a lichen to the tree cortex and other substrates.
2. In the middle part there are also hyphals, but they are wobbly, and there are single-cell algae between them. And the inner layer is represented by gifs, between which the emptiness filled with air is lying.
3. W. momeric Lichenniki (collem, leptogium) Cells of algae are not localized in one layer, and distributed chaotic, sometimes one by one, sometimes forming a chain.

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Lichens represent a complex object for physiological studies, as they consist of two physiologically opposite components - a heterotrophic mushroom and autotrophic algae. Therefore, it is first to separately study the livelihoods of Miko and Ficobiont, which is done with the help of cultures, and then the life of a lichen as a holistic organism. The process of photosynthesis in lichens depends on many environmental factors (illumination, temperature, humidity, etc.). The chloroplasts of algae cells in the layer under the cow layer from the GIF are obtained slightly less than the chloroplasts under the epidermis in the leaves of higher plants. A cowing layer covering the layer, performs the function of protection against excessive intensive radiation in open places. The maximum intensity of photosynthesis is observed in lichen with illumination within 4000-23000 LCs - such light indicators are characteristic of most of their habitats in the tundra, flavoring, light coniferous forests. Where the illumination is higher, the layer is protected by dark pigments and lichen substances.

Topic optimum photosynthesis for most lichens is in the range from -10 - +25. For normal photosynthetic activity, the layer should contain a certain amount of water, depending on the anatomy-morphological type of lichen. In general, in thick layers, the optimal water content for active photosynthesis is lower than in thin and loose layers. Lichens absorb water (in the form of rain, snow, fog, dew, etc.) very quickly, but passively with the entire surface of your body and partly the rhizoids of the underside. Such an absorption of a layer water is a simple physical program, such as, for example, water absorbing with filter paper. Lichenss are able to absorb water in very large quantities, usually up to 100-300% of the dry mass of the layer, and some mucous lichens (collems, leptogiums, etc.) even up to 800 3900%.

The minimum water content in lichens in natural conditions is approximately 2-15% of the dry mass of the layer. The return of water with a layer occurs pretty quickly. Water-saturated lichens in the sun after 30-60 minutes lose their entire wrestle and are made fragile. From this there is a peculiar "arrhythmia" of photosynthesis of lichens - its productivity changes during the day, time of year, a number of years, depending on the general environmental conditions, especially hydrological and temperature.

The breathing of lichens is directly connected with photosynthetic activities. It is shown that it is generally lower than that of higher plants, and is an average of 0.2 - 2.0 mg of carbon dioxide for 1G dry mass for 1 hour. Since most lichen in the layer in volume and mass dominates the combustion component It is believed that the respiratory intensity is mainly due to the vital activity of micaopte. Breath depends on the content of water in the layer and on temperature. An increase in water content is accompanied by an increase in respiratory intensity, and, on the contrary. The amplitude of the temperature at which the breathing of lichens is possible, wide: from -15 to +30, +50, while the optimum breathing is commonly observed in the range from +15 to +20. When the temperature is raised from 0 to + 35`C, the respiratory intensity increases, and at + 35`c absorption and regeneration of carbon dioxide are balanced.

An important component in the nutrition of lichens is nitrogen. Those lichens, which have green algae as a ficobion, perceive nitrogen compounds from aqueous solutionsWhen their layers are soaked with water. It is possible that part of nitrogen compounds take and straight from the substrate - the soil, the bark of trees, etc. As for other nutrition components involved in the metabolism, especially the mineral elements, then the ability of lichens to accumulate in their layer, those substances, which in such quantities for its normal life, seemingly not needed. The biological meaning of such accumulation is not installed.

Lichens

Lichens is a kind of group of living organisms growing on all continents, including Antarctica. In nature, there are more than 26,000 species.

For a long time, lichens were a riddle for researchers. However, they have not yet come to a common opinion regarding their provision in the systematics of wildlife: some refer to the kingdom of plants, others - to the kingdom of mushrooms.

Lichen's body is represented by a layer. It is very diverse in color, sizes, shape and structure. The layer can have a body shape in the form of a crust, a leaf plate, tubes, bustle and a small rounded lump. Some lichens reach a length of more than a meter, but most have a layered 3-7 cm in size. They slowly grow - in the year they increase into a few millimeters, and some on the shares of a millimeter. The age of their layers often has several hundred and thousands of years.

Lichens do not have a typical green color. The painting of lichens is grayish, greenish-gray, light or dark-brown, less than yellow, orange, white, black. Coloring is caused by pigments that are in the shells of gif mushroom. There are five groups of pigments: green, blue, purple, red, brown. The color of lichens can also depend on the color of lichen acids, which are deposited in the form of crystals or grain on the surface of the hyphae.

Alive and dead lichens, which accumulated on them dust and grains, create a non-naked ground, a thin layer of soil, in which mosses and other land plants can be gained. Grounding, mosses and herbs shade terrestrial lichens, fall asleep with them from the sterling parts of their bodies, and lichens with time disappear from this place. Lichen vertical surfaces falling asleep does not threaten - they grow up and grow up, absorbing moisture of rains, growing and fogs.

Depending on the appearance of the layer, lichens are divided into three types: precipitated, sheets and bushy.

Types of lichens. Morphological features

Lichens - the first settlers on the naked soil. On the bare stones, the sun, on the sand, on the brothers and trunks of trees.

Name of lichen	The form	Morphology	Habitat
Scale (about 80% of all lichens)	View of a crust, thin film, different colors tightly contrived with the substrate	Depending on the substrate on which scaling lichens grow, distinguish: epilite epifeloid epigene epixyl	on the surface of rocks; on the crust of trees and shrubs; on the surface of the soil; On rotting wood
	Lichetic layer can develop inside the substrate (stone, bark, tree). There are precipitated lichens with a spherical shape of the layer (walker lickers)
Leaded	Tall has the form of scales or fairly large plates. Monophilic - view of one large rounded sheet plate (in diameter 10-20 cm). Polyfyl - Layer of several sheets	Attach to the substrate in several places with mushroom gif beams	On the stones, the soil, sand, the bark of trees. The substrate is firmly attached by a thick short leg. There are misunderstood, worst forms
	A characteristic feature of sheet lichen is that its upper surface is different in structure and color from the bottom
Bushy. Height of small - several millimeters, large - 30-50 cm	In the form of tubes, funnels, branching tubes. View of Kusta, a reprehensive or hanging, strongly branched or undiscarted. "Bearded" lichens	The layers are flat and rounded blades. Sometimes large bush lichens in the conditions of the tundra and high spirits are developing additional attachment (gapters), with the help of which they grow to the leaves of the Osk, cereals, shrubs. Thus, lichens protect themselves from the separation of strong winds and storms	Epiphytes - on the branches of trees or rocks. The substrate is attached by small sections of the layer. Inhanded - Fit-shaped rhizoids Long strip - 7-8 meters hanging in the form of a beard from the branches of larch and cedar in the taiga forests
	This is the highest stage of the development of the layer

In extremely harsh conditions, lichens are growing on stones and rocks in Antarctica. Live organisms have to live here at very low temperatures, especially in winter, and practically without water. Due to the low temperature, the precipitation is always falling in the form of snow. A lichen cannot absorb water in such a form. But it helps the black color of the layer. Due to the high solar radiation, the dark surface of the lichen body is quickly heated even at low temperatures. Snow that fell on a heated layer, melts. The lichen that appears moisture immediately absorbs, providing itself with water necessary for breathing and photosynthesis.

Structure

The layer consists of two different organisms - mushroom and algae. They interact so closely among themselves, that their symbiosis is represented by a single organism.

The layer is a variety of intertwined mushroom threads (GIF).

Between groups or single cells are located green algaeand in some - cyanobacteria. Interestingly, the types of mushrooms that make up a lichen in nature do not exist without algae, while most algae included in the licrayer is found in free-lived condition, separately from the mushroom.

The nutrition of the lichen is carried out by both symbilations. Gifs of the mushroom absorb water and dissolved in it minerals, and alga (or cyanobacterium), in which there is chlorophyll, forms organic substances (thanks to photosynthesis).

Gifs play the role of roots: they absorb water and mineral salts dissolved in it. Cells of algae form organic matter, perform the function of leaves. Water lichens absorb the entire surface of the body (use rainwater, moisture fogs). An important component in the nutrition of lichens is nitrogen. Those lichens, which are green algae as a ficobiont, receive nitrogen compounds from aqueous solutions, when their layer water is soaked with water, partially directly from the substrate. Lichenniki, having blue-green algae as a ficobion (especially Nostoki), are able to record atmospheric nitrogen.

Internal structure

This is a peculiar group of lower plants, which consist of two different organisms - mushrooms (representatives of ascomitzets, basidiomycetes, ficomyzetov) and algae (green - Cystococcal, Chlorococcus, Chlorella, occurs to the Kladfofor, Palmell; blue-green - Nostok, Gleokaps, Chropokk) forming Symbiotic cohabitation, characterized in special morphological types and special physiological biochemical processes.

The anatomical structure is distinguished by lichens of two types. One of them algae scattered throughout the thickness of the layer and immersed in the mucus, which highlights the alga (homeomeric type). This is the most primitive type. Such a structure is typical for those lichens, whose ficobionom are blue-green algae. They form a group of mucous lichens. In the other (heteromeric type) on the cross section, you can distinguish several layers under the microscope.

From above there is an upper bark having a kind of intertwined, closely closed mushroom hyphae. Under it, the gifs lie more loose, there are algae between them - this is a gonidial layer. Below, the fungal gifs are located even more loose, large gaps between them are filled with air - it is the core. Over the core follows the lower bark, which is similar to the top. Through the bottom bore from the core pass guys, which attach a lichen to the substrate. The cortical lichens of the lower cortex does not have and mushroom core gifs grow directly with the substrate.

In bushy radially built lichens on the periphery of the transverse section there is a bark, under it a gonidial layer, and inside - core. Bark performs protective and strengthening functions. Attachments are usually formed on the lower cow layer of lichens. Sometimes they have the form of subtle threads consisting of one row of cells. They are called rhizoids. The rhizoids can be combined, forming rizoidal chips.

Some leaf lichen is attached with a short leg (gomfa) located in the central part of the layer.

The algae zone performs the function of photosynthesis and the accumulation of organic substances. The main function of the core is air to carry out air to algae cells containing chlorophyll. Some bush lichens, the core performs and strengthens the function.

The gas exchange authorities are pseudocyphella (bark breaks, visible to the unarmed eye as white spots of the wrong shape). On the lower surface of the leafy lichens there are round correct shapes. White recesses are digits, also gas exchange organs. Gas exchange is carried out through perforations (dead sections of the cow bed layer), cracks and breaks in the cow layer.

Reproduction

Lichens multiplies mainly by pieces of layers, as well as by special groups of mushroom cells and algae, in a variety of generated inside its body. Under the pressure of their scratched mass, the body of the lichen is broken, the cell groups are spread by wind and raindrops. In addition, mushrooms and algae retained their own propagation methods. Mushrooms form disputes, algae multiply vegetative way.

Licheniki multiply either by disputes that form micaobion by sex or sexually, either vegetatively fragments of layers, samples and friction.

With sexual reproduction on layers of lichen, sexual spiones are formed in the form of fruit bodies. Among the fruit bodies, lichens distinguish approaches (open fruit bodies in the form of discoid formations); Peritiation (closed fruit bodies having a look of a small jug with a hole at the top); Gaster descendants (narrow fruit bodies elongated form). Most lichens (over 250 genera are formed apotection. In these fruit bodies, disputes are developing inside bags (bags) or exogenous, on top of extended-male-like GIF - Basidi. The development and ripening of the fruit body lasts for 4-10 years, and then for a number of years, the fruit body can produce disputes. The dispute is formed a lot: so, one of the apotations can produce 124,000 disputes. They germinate not all. For germination, conditions are needed, first of all, certain temperatures and humidity.

Pollution of licorion of lichens - conidias, picnokonia and stylish, arising exogenously on the surface of the conidium. Conidia is formed on the conidiens developing directly on the surface of the layer, and picnokonia and stylish - in special containers of picnides.

Vegetative reproduction is carried out by the bunches of layers, as well as special vegetative formations - for sorties (dust - microscopic gloves, consisting of one or more algae cells, surrounded by gifs of the fungus, form a fine-grained or powdery whitish, yellowish mass) and friction (small variety of shapes of the upper surface of the layer , one with her color, have the kind of warts, grain, male-shaped grows, sometimes small leaves).

Lichens - Pioneers of vegetation. Setting on the ground, where other plants can grow (for example, on the rocks), they after a while, partially dying, form a small amount of humus, where other plants can live. Lichens destroy rocks, highlighting lichen acid. This destructive action finish water and wind. Lichenics are able to accumulate radioactive substances.

Lichens - Building, breeding and ways

Lichens is a very interesting and peculiar group of lower plants. Lichens (Lat. Lichenes) - symbiotic associations of mushrooms (microeats) and microscopic green algae and / or cyanobacteria (photobione, or ficobiont); Mikobiont forms a layered (tall), inside which photobionate cells are located. The group numbers from 17,000 to 26,000 species of about 400 genera. And every year, scientists discover and describe dozens and hundreds of new unknown species.

Fig.1. Lichen Cladonia Starla Cadonia Stellaris

The lichen combines two organism with opposite properties: alga (more often green), which in the process of photosynthesis creates an organic substance, and a mushroom that consumes this substance.

Like organisms lichens were known to scientists and people long before the discovery of their essence. Another great theophrast (371-286 BC), "Father Botany" gave a description of two lichens - USNIA (USNEA) and Rochelle (ROSS11A). The latter was already used to obtain coloring substances. The beginning of the Lichenology (science of lichens) It is considered to be 1803, when the student of Charles Lynnei Eric Ajaraius published his work "Methodus, Qua Omnes Detectos Lichenes Ad Genera Redigere Tentavit" ("Methods with which everyone can define lichens"). He highlighted them into an independent group and created a system based on the structure of the fruit bodies, which includes 906 species described at that time. The first on the symbiotic nature in 1866 on the example of one of the species indicated the doctor and Mikogol Anton de Bari. In 1869, Botanist Simon Schwenden distributed these ideas on all types. In the same year, Russian nerds, Andrei Sergeevich Famyshn and Osip Vasilyevich Baranetsky discovered that green cells in a lichen - single-celled algae. These discoveries were perceived by contemporaries as "amazing".

Lichens are divided into three unequal groups:

1. It has a greater number of lichens, a class of sample lichens, because formed by stembed mushrooms

2. Small group, class of basidial lichens, because formed by basidial mushrooms (less stable mushrooms)

3. "imperfect lichens" got their name due to the fact that they were not fruit bodies with disputes

The world of nature is unique and unthinkable. Every year, scientists perform new and new discoveries that disclose the extraordinary prospects of studying the world around us. But also quite familiar living organisms, which a person knows from time immemorial, is still able to amaze. Take, for example, lichens. They are simple, but their peculiarities are very unusual.

Do you know the lichens do you eat? This is a truly unique process that is worth describing in detail.

Complexity of knowledge

In general, they are quite difficult to study, as they are symbiosis of completely different organisms. Each lichen is formed by symbiosis of autotrophic algae and heterotrophic mushroom. It is clear that you first have to study the biochemistry and vital activity of each organism separately. This method of studying their physiology gives many mistakes and errors, and therefore scientists have a huge number of questions, far from all of which have answers. However, the researchers still managed to identify common patterns.

Internal structure

In general, the whole body of lichen is a massive weave of mushroom hyphae, inside of which the colonies of autotrophic algae are located. Today, the following types of lichens are distinguished in science:

• Momeric varieties (Collema). Cells of photobionate colonies (algae) in chaotic order scattered by body.
• Heteromeric (Peltigera Canina). On the cross cut, you can clearly see the layers of tall (GIF) and algae.

Most of all there are lichens, the structure of which is based on the last principle. In this case, the entire top layer is formed by a particularly dense plexus of mushroom fabric, which protects the body of lichen from negative impacts. external environment. In addition, the mushroom prevents overly rapid drying (but it does not always help).

The following layer is a colony of autotrophic algae. In the very center there is a lichen core, which is a tight litigation from the intertwined gif mushroom and autotrophop colony. This "rod" has a dual function: on the one hand, the lichen pans in the core water. On the other, this is a kind of skeleton of this body. In the lower part are rizins. This is a kind of attachment, with which the lichen clings to the substrate. It should be remembered that the full set is far from all kinds.

Some types of lichens (cyanolishes) are characterized by the fact that their structure has highly localized colonies of cyanodorosyl. These species, the separation on the layers is particularly well expressed. So how do lichens eat? The answer to this question is directly related to the features of them.

About the process of photosynthesis

There are thousands of studies that are devoted to precisely the peculiarities of photosynthesis in these symbiotic organisms. Since about 10-15% of their volume is occupied by algae, which gives them almost everything arises many questions about the intensity of the process. Oddly enough, the simplest dimensions unequivocally showed that the intensity of photosynthesis in lichens is significantly lower, if we compare them with higher autotrophic plants. So, when conducting an analogy with ordinary potatoes, the ratio will be 1:16.

But how to explain quite comfortable vital activity in such spartan conditions? In general, nothing particularly difficult in it. The fact is that authotrophic higher herbal organisms most of their lives are "awake", while lichens in some localities hardly all year are in half dried state, in Anabiosis. Of course, it is enough for a meager amount of nutrients to maintain vital activity.

This is how lichens eat. Grade 7 in biological orientation schools can study this topic more, but also in this case, answers to many important questions Standard educational program does not give. For example, when the process of forming organic substances for nutrition proceeds slower, and when - a little faster?

What does the intensity of photosynthesis depend on lichens?

It should be noted that the intensity of this process depends on the set of a wide variety of factors. It is also important that chloroplasts, being covered with a dense layer of GIF, are far less than the light than similar formations in higher autotrophic plants and even algae. In principle, this difference is not so significant.

It should be known that the maximum value of the photosynthesis process is observed when illuminated within 4000-23000 LCs. Such can be found in the main habitats of lichens: tundra, forest-steppe, bright northern forests. In areas where the lighting intensity is significantly higher, intensive production of the dark organic pigment (parity), as well as specific substances (suitranurin, for example) begins in the body of a symbiotic organism.

The resulting as a result of photosynthesis is completely similar to those that are used in trophic purposes. This is how lichens eat. Grade 7 of the secondary school examines the processes of their livelihoods are very superficially, although this theme is big and extremely interesting. We bring to your attention extended information that may not only be interesting, but also useful.

Respiratory process

It is easy to guess that the production of nutrients directly depends on respiratory. Unlike photosynthesis of lichens, it is intensive: only one gram of a symbiotic organism is distinguished by a 4-2.0 mg. If you carefully read information at the top of the article, then surely realized that about 85-90% of the mass of the lichen accounted for by the weight of the micaopon. Simply put, the mushroom part needs more in oxygen, and not autotrophic algae. As lichens eat under normal conditions is not too regular (reason - harsh climatic conditions), Considerable part of nutrients is intensified in their tissues.

As well as photosynthesis, the process of respiration directly depends on the percentage of water.

It should be known that the minimum level of breathing, which is necessary to obtain a certain amount of energy from nutrients, the lichen retains almost under any conditions (suitable for life, of course). This process is possible during the following temperatures: from -15 to +30, +50 ° C. But the optimal temperature regime is in the range from +15 to +20 ° C. The use of oxygen begins to prevail with cooling. And when raising the temperature above +35 degrees, both processes are approximately aligned.

The case is known when the lichen (the photo of this species is in the article), brought to one of the Moscow museums by another expedition of the royal archaeological society, quietly restored its livelihood, being placed one of the employees in flower pot with slightly damp ground. But by that time, he has already been in an absolutely dry, closed box for exhibits and most of the time even the light was deprived of the exhibits and most of the time!

It is not surprising that this organisms are so interested in modern biology. Lichens certainly have a lot of secrets, whose disclosure may notice the development of medicine.

Scientists have proven that the basic principles of the respiration of lichens are subject to the same laws as in the case of higher autotrophic plants. But there are differences, the main of which is a slightly different priority between the absorption of oxygen and the separation of carbon dioxide. In addition, they are phenomenally resistant to drying, low and high temperatures. No wonder moss and lichens can grow even in the conditions of the Arctic.

Temperature mode

The most favorable for photosynthesis in lichens the temperature range from +10 to +25 degrees Celsius. But the ability to absorb carbon dioxide for them is preserved up to -25 degrees. This is a very remarkable feature of lichens, which distinguishes them from higher plants and even algae. At temperatures from -5 to -10 degrees, the intensity of the absorption of carbon dioxide is hardly more than in more comfortable conditions. In many plants, in this case, ice is formed in the intercellular space, which simply breaks cells.

Unlike them, lichens on trees, the trunks of which literally breaks the harsh northern climate (cracking frosts), feel great when the warm season occurs.

Water exchange features

The researchers came to the conclusion that lichens differ in a special, extremely specific type of water exchange. The fact is that water in their body is contained in spaces between durable gifs. When it freezes, it does not bring much harm, and the process of photosynthesis and nutrition continues to occur. However, with an increase in temperature to +35 degrees on the Celsius scale and more, the photo content process almost stops, which radically distinguishes lichens from plants.

The amount of water that will be enough for normal life depends on the family. So, bushy lichens are capable of photosynthesis and the production of organic substances for nutrition almost with full dehydration. The thicker the body, the more moisture can accumulate in it, the less it evaporates.

This is especially important for lichens, since in most cases they grow in very difficult conditions, when more or less regular water intake is completely not guaranteed. In such conditions, any plant would die. The lichen feels nicely even in the conditions of real deserts and the Arctic.

Regulation of liquid exchange

It can be understood that the regulatory function of the water exchange in these organisms is arranged in a completely different way than at the highest plants. Since they have practically no specialized systems for this. For example, the absorption of water is extremely quickly, but only due to the ordinary absorption of it with the entire surface of the body. You can spend the simplest experience: pour a small amount of water on the table and put a piece of napkins or toilet paper on the puddle.

As you can see, the water instantly absorbed, as the paper structure has a good absorbent ability. The same thing happens in the case of lichens. So, we viewed the episode with a long time ago a dried copy, which was once brought by an expedition. When an employee put a lichen in a flower pot, he simply instantly absorbed such a volume of fluid, which he was enough to restore life.

Some bushy lichens are capable of absorbing a huge amount of fluid, the weight of which is up to 300% of their own. Other types (collems, leptogiums) increase thus in size by 400-3900%! If we talk about the minimum water content, then it is approximately 2% of the weight of the dry matter of the lichen. Such a lichen (photos can be found in this material) by type absolutely not similar to a living organism.

About water return

As in the case of toilet paper, gives water the body of a symbiotic organism quite quickly. In just an hour, a lichen, who has just absorbed hardly a liter of fluid, can dry to a brittle state. Thus, the "productivity" of these organisms is extremely cyclical: the production of trophic substances can change radically not only during the season, but also for one or two hours!

IN last years Scientists have learned that some types of lichens living in the tundra (Evernia Prunastri) may well use literally "crumbs" of sunlight, occasionally breaking through the layer of snow. Simply put, they don't finish even in winter photosynthesis.

Reproduction of lichen

In addition, the features of lichens are in the presence of three ways of reproduction at once:

• Vegetative.
• Sexual.
• Asexual.

Mushroom, that is, the micaobion can be multiplied by all methods, while alga is capable of vegetative division exclusively. Spores of the mushroom are located in special bags. Ascoming lichens for the reproduction process uses two main groups of fruit bodies: Auditations and peritiations. Their characteristics are as follows:

• Apottions is the usual bed of a rounded form. It contains bags that are located in the intervals between ordinary, not ending with gifs. This openly located layer is called the hemium.
• Peritiation is similar to a practically completely closed structure of a spherical form. Disputes are released through special holes that are located on the surface of the fruit sphere.

Some species can also form useless disputes, picnospores (picnokonia). The place of their formation is picnia. These are spherical bags or several pear shapes, which are highly specialized gifs. Picnia is easy to recognize, as they look like black points located on the bed.

When the disputes wake up, they are in suitable conditions Quickly give the beginning of new hyphae forming the body of a new lichen. They (gifs) also penetrate inside the cells of autotrophic algae, after which the formation of a new organism actually ends.

Value

In general, mosses and lichens are tremendous. In Tundre I. arctic desert They are often the only ones that can accumulate nutrient organic substances in extremely unfavorable conditions. Simply put, it is these organisms that are a source of food for those few herbivores that can accommodate in such harsh places. In addition, only lichen on trees, even in the conditions of our climate, often allow you to survive the winter, for example, elk and root.

Currently described about 26 thousand types of lichensIn reality, their number can reach 40 thousand. It is believed that they were the first organisms that began to settling land. Initially, it was they formed the soil on Earth.

Lichens is a rather complicated object. These ancient organisms appearing, as scientists consider, more than 400,000,000 years ago, are incredibly interesting for study.

In contact with

The complexity of the study of the lichen is that it can not even be determined as a separate organism. A lichen is a symbiosis - a composite organism of two organisms: mushroom and algae. Lichens possess special biological properties that are not inherent in other organisms. A kind of metabolism, the formation of specific lichen substances, in the synthesis of which both components of the lichen take part, methods of breeding and so on.

Separately, existing, algae does not have the properties that it acquires, entering into symbiosis with the mushroom. The causes of permanent algae-haul organisms of scientists are still clear to the end. Possible causes are called "Hunger" of the fungus, that is, the conditions of lack of nutrients, as a result of which the mushrooms found themselves a partner in the face of algae, which provide them with the necessary organic substances. Also the reason for the combination of mushrooms and algae could be the dryness of their habitats.

Structure

The way lichens is arranged in detail below the microscope. Thread mushrooms (gifs) tear colonies unicellular algae. Outside, the gifs of the fungus are woven more tightly, forming the so-called bark, and inside the weave is not so dense - this part is called the core.

The colony of algae is trying to be located as close to the upper and outdoor parts. This is explained by the fact that the algae needs sunlight, because it is powered by photosynthesis.

Life forms

In nature, lichens meet us quite often. Just being in the forest, we can meet many representatives of this species. Basically you can see three types:

1. Boiled. We are more common on the stones, the incentive to them is very tight.
2. Leafy. You can see them on the trunks of the trees. In shape they look like layered growths.
3. Bushy. Rimmed over the place where they grow in the form of "twigs".

Food

The lichen consists of:

1. Avtrophic organism - algae.
2. Heterotrophic - mushroom.

If you are briefly described, it turns out that the threads of the fungus absorb water (water is absorbed by the entire surface of the body, like a sponge) and minerals (and the mushroom is capable of extracting them from naked rocks, highlighting substances that destroy the breed), and in algae cells in The process of photosynthesis is formed by organic substances, which, in turn, absorbs the mushroom. But, as it turns out, everything is much more difficult.

Scientists have not yet been able to fully understand how the fungus is able to stimulate algae not only on the production of substances necessary for its nutrition, but also on the release of these substances in the quantities of large than this occurs in separately existing algae. Separately, existing algae allocates only 10-15% of the organic substances obtained by it in the process of photosynthesis to the environment. Being as a lichen, the same algae will allocate 80−85% synthesized organic matter that will be absorbed by the mushroom.

It is assumed that the mushroom affects the cells of algae with some kind of chemicals, and this effect increases the number of organic substances secreted by algae. Also possible and direct physical impact that occurs by contacting mushroom hyphae and algae cells.

The ways of transmitting organic matter from one participant of the composite organism to another are also not completely clear. Not so long ago, scientists managed to find out in the form of what substances an exchange of organic. In one case, it is glucose, in the other - polyatomic alcohols.

Also an important component is nitrogen. Depending on which types of algae are part of, this element is lichen can be obtained from:

1. Air.
2. Water.
3. Substrate (stone, soil, plant bark).

The distribution of nitrogen compounds is set strict control, and most of these substances are absorbed by the mushroom.

Conditions of existence

Lichens are incredibly unpretentious organisms. They can grow, for example, on bare stones, many grow in the harsh conditions of the extreme north or deserts.

Temperature range of life in these organisms is incredibly wide: from -70 to +60 degrees Celsius. They are able to exist in the absence of water, hidden, and then returning to life.

It is believed that these amazing organisms that can exist almost in all over the range natural conditions On our planet, you are not able to live in anthropogenic pollution ambient. This applies not to all forms, but in general, chemicals actively allocated in the process of human activity into the environment are detachious for lichens.

The most unsuitable in this sense are bushy lichens. When air pollution, they will die quickly. Slightly less sensitive sheets. But why are the form that managed to adapt to adverse conditions. They are able to live even in urban conditions.