Lichens can be found almost everywhere, even in Antarctica. This group of living organisms has been a mystery to scientists for a long time; even now there is no consensus on their systematic position. Some believe that they should be classified as a plant kingdom, while others believe that they should be classified as fungi. Next, we will consider the types of lichens, the features of their structure, their significance in nature and for humans.
General characteristics of lichens
Lichens are a lower 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. There is mutually beneficial cohabitation between these two representatives of the living world.
Lichens, regardless of the variety, are not green in color; most often they can be gray, brown, yellow, orange or even black. This depends on the pigments, as well as the color of the lichen acids.
Distinctive features of lichens
This interesting group of organisms is distinguished by the following features:
- The cohabitation of two organisms in a lichen is not accidental; it is determined by historical development.
- Unlike plants or animals, this organism has a specific external and internal structure.
- The physiological processes occurring in fungi 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.
- A special method of reproduction.
- Attitude to environmental factors.
All these features confuse scientists and do not allow them to determine a permanent systematic position.
Varieties of lichens
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:
- Scale lichens. They got their name from their shape, similar to scale.
- Foliaceous lichens. They look like one large leaf blade, hence the name.
- Fruticose lichens resemble a small bush.
Let's look at the features of each type in more detail.
Description of crustose lichens
Almost 80% of all lichens are crustose. In their shape they look like a crust or a thin film, firmly fused with the substrate. Depending on their habitat, crustose lichens are divided into:
Due to its special appearance, this group of lichens can be completely invisible and blend in with the environment. The structure of crustose lichens is unique, so they are easy to distinguish from other species. But the internal structure of almost all is the same, but more on that later.
Habitats of crustose lichens
We have already looked at how crustose lichens got their name, but the question arises: do the habitats differ? 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.
Crustaceous types of lichens are distributed throughout the planet. Depending on the substrate, one or another species predominates. For example, in the Arctic you cannot find species that are common in the taiga, and vice versa. There is a connection to a certain type of soil: some lichens prefer clay, while others feel comfortable on bare rocks.
But among the great diversity of this group of organisms, you can find species that live almost everywhere.
Features of foliose lichens
The thallus of this species looks like medium-sized scales or plates, attached to the substrate using a bunch of fungal hyphae. The simplest thallus resembles a rounded leaf blade, which can reach 10-20 cm in diameter. With this structure, the thallus is called monophyllous. 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
Bushy lichens received this name 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 dimensions 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 being torn off from the substrate in strong winds.
Internal structure of lichens
Almost all types of lichens have the same internal structure. Anatomically, two types are distinguished:
It should be noted that those lichens that belong to crustaceans do not have a lower layer, and the hyphae of the core directly grow together with the substrate.
Feeding features of lichens
Both organisms living in symbiosis take part in the feeding process. 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 perform the function of leaves. Since for the most part lichens settle on lifeless substrates, they absorb moisture over their entire surface; not only rainwater, but also fog and dew are suitable for these purposes.
For normal growth and functioning, lichens, like plants, require nitrogen. If green algae are present as a phycobiont, then nitrogen compounds are extracted from solutions when the thallus is saturated with moisture. It’s easier for lichens, which have blue-green algae; they are able to extract nitrogen from the air.
Reproduction of lichens
Regardless of the variety, all lichens reproduce in the following ways:
Considering that these organisms grow very slowly, we can conclude that the reproduction process is quite long.
Ecological role of lichens
The importance of this group of organisms on the planet is quite great. They are directly involved in the process of soil formation. They are the first to settle in lifeless places and enrich them for the growth of other species.
Lichens do not require a special substrate to function; they can cover barren territory, preparing it for plant life. This is explained by the fact that in the process of life, lichens secrete special acids that contribute to the weathering of rocks and enrichment with oxygen.
Settling on bare rocks, they feel absolutely comfortable there and gradually create favorable conditions for other species. Some small animals are able to change their color to match the color of lichens, thus camouflaging and using them for protection from predators.
The importance of lichens in the biosphere
Currently, more than 26 thousand species of lichens are known. They are distributed almost everywhere, but surprisingly they can serve as an indicator of air purity.
These organisms are quite sensitive to pollution, so in large cities you will hardly find lichens near roads or factories. They simply do not survive there and die. It should be noted that crustose lichens are the most resistant to poor natural conditions.
Lichens also take a direct part in the cycle of substances in the biosphere. Since they belong to autoheterotrophic organisms, they easily accumulate the energy of sunlight and create organic substances. 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 in trees, these symbiotic organisms cause virtually no harm, since they do not penetrate deep into living tissues. In a way, they can even be called protectors, because a plant covered with lichens is less susceptible to attacks by pathogenic fungi; lichen acids suppress the growth of wood-destroying fungi.
But there is also a downside: if the lichens grow too much and cover almost the entire tree, they cover the lentils, disrupting gas exchange. And this is an excellent refuge for insect pests. For this reason, it is better to control the growth of lichens on fruit trees and clean the wood.
The role of lichens for humans
We cannot ignore the question of the role of lichens in human life. There are several areas where they are widely used:
Lichens do not cause any harm to human economic activity.
To summarize all that has been said, we can say that such inconspicuous and amazing organisms exist next to us. Despite their small size, their benefits are enormous, for all living organisms, including humans.
A lichen is traditionally considered to be an association of fungus and algae that has a thallus. Its “framework” is provided by a mushroom, and it also holds the algae with the help of special suction cups (compare with “sea lichen”). An important property is the ability of these organisms to produce their own acids. An association may include 1 species of fungus and 2 species of algae or cyanobacteria. The oldest finds include specimens found in China in marine fossils 550-640 million years ago. The first mentions were found in an illustrated book by Theophrastus from the 300s BC.
In botany, these organisms are not classified as a separate taxonomic group. All species are named after the fungal component (for example, xanthorium).
According to the nature of the thallus, lichens are distinguished:
- homogeneous on the cut (colemma). This species includes crustose lichens;
- heterogeneous (cladonia, xanthoria). Representatives of this species are bushy forms. Such forms are often colored differently.
The diversity of lichens is distinguished mainly by life forms:
All members of this family have symbiotic associations with green algae (trebuxia), which is why they are considered very representative specimens (about 50% of varieties include this component).
There are representatives of bushy and leafy forms. Parmelias, within the same species, are found in various colors: white, gray, with the presence of green, yellow or brown shades. When cut, they can be homogeneous or heterogeneous. When potassium lye is applied to the thallus, it begins to turn yellow.
Due to the extremely high morphological diversity and complexity, many specimens are difficult to accurately identify to the species level.
The family is distributed in all climatic regions (from the tropics to the Arctic); species can grow on many types of substrate: on trunks and branches of various tree species (living and dead), as well as on stones. Prefers places with good lighting. Relatively easily adapts to the polluted air of large cities.
The example of Parmelia shows that the classification of lichens by form does not always correspond to the actual position.
The genus received the name “cut grass” for its hemostatic properties. Red Army soldiers used parmelia powder to treat wounds during World War II. It was also used as an additive for flour.
Problematic and useful moss
It is often not clear which groups of lichens belong to moss. This name may refer to the following species:
- representatives of the clans Cladonia and Cetraria;
- fruticose lichens;
- foliose lichens;
- crustose lichens.
Many “popular sources” consider moss moss and “reindeer moss” to be exact synonyms, but this is not the case. In these species, a foliose thallus first develops, which later turns into a bushy thallus. These are the exceptions to the rules.
Yagel in the service of history
Crucible lichens helped determine the age of the stone idols of Easter Island. Comparing photographs taken about 100 years ago with modern measurements helped calculate the average annual growth of this plant. Now, thanks to extreme species, scientists are clarifying data on the movements of glaciers and changes in their size.
Found beneath layers of volcanic ash from Vesuvius, orange-hued textile materials appear to have been treated with dyes based on a local species of xanthorium.
It is known that the Vikings used reindeer moss in baking, so finds of its components may be evidence of their presence in remote places.
Application in medicine
Due to the high content of usnic acid, sometimes up to 10 percent by weight, many have antibiotic and analgesic properties. According to some reports, this substance can slow down the development of tuberculosis. But remember, a large amount of acid is a contraindication, and not a desirable indicator, as there is a health hazard. For this reason, bearded lichen and many types of moss need to be soaked in a solution of baking soda or for a longer time in clean running water. Derivatives of this acid are capable of killing many types of bacteria and suppressing the proliferation of highly resistant ones that have developed resistance to commonly used antibiotics. The peoples of the north use the healing properties of “reindeer moss” in folk remedies.
Cetraria have found use in the production of medicines against diarrhea, viral and microbial colds, and to stimulate hunger in gastrointestinal disorders.
Contraindications: preparations based on moss moss are not recommended for use by pregnant and lactating women due to the individual sensitivity of small children and the tendency to develop allergies.
If you start using “natural preparations”, do not forget to consult with qualified specialists.
Use in the food industry
During the Civil War, due to a shortage of wheat flour, dried lichens stored in pharmacists' warehouses were used.
In northern countries, reindeer moss is used to feed small and large ruminants and pigs due to its high satiety, which is three times higher than potatoes. In Sweden, folk alcoholic drinks based on lichens are still brewed today.
Recently, an innovative project for the production of bread, seasonings and even confectionery was launched in Yamal. They promise that the following fast food menu will appear: crackers, the production of which does not require yeast, several types of sauce, buns and other goodies. We must not forget that due to the newness of the product, contraindications have not yet been fully studied.
Determination of the environmental situation
With an increase in air pollution, fruticose lichens disappear first, then foliose lichens, and lastly scale lichens (Xanthoria eleganta). Due to the change in color of xanthoriums, butterflies in industrial areas also change their colors, usually to dark gray shades.
The closer to the center of pollution the indicator organism is, the thicker its body becomes. With increasing concentration, it occupies less area and reduces the number of fruiting bodies. When the atmosphere is heavily polluted, the surface of most lichens acquires white, brown or purple shades. The most dangerous pollutant for them is sulfur dioxide. If you suffer from diseases of the respiratory system and have discovered the above-mentioned features of these organisms, then you can perceive this as contraindications for further living in such a place.
- (Lichenes), organisms formed by the symbiosis of a fungus (mycobiont) and algae (phycobiont); traditionally belong to lower plants. Early fossils of L. presumably belong to the top. chalk. Occurred as a result of the transfer 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 can exist with different fungi.... ... Dictionary of microbiology
LICHENS- LICHENS, lichens, Lichenes, a peculiar class of lower plants, consisting of a fungus and algae, together forming one organism. Lichen fungi, with minor exceptions, are marsupials. Algae of L. have the common old name of gonidia. Not… … Great Medical Encyclopedia
Polyphyletic group of fungi Ernst Heinrich Haeckel ... Wikipedia
- (Lichenes), a widespread group of symbiotic organisms, usually growing on stones or tree trunks, less often on soil, and receiving the moisture they need for life from the atmosphere. Several species live in the marine littoral zone (tidal... ... Collier's Encyclopedia
- (Lichenes) a specialized group of fungi that are in constant cohabitation with algae; Some botanists consider L. as an independent group of lower plants. The science of L. is called lichenology (See Lichenology).... ... Great Soviet Encyclopedia
lichens- ▲ lower plants lichens are symbiotic organisms formed by a fungus and an algae. moss, reindeer moss. Cladonia. cetraria. | manna. soredia. | lichenology. cover up. mossy. moss. 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: engl. lichens vok. Flechten, f; Lichenen rus. lichens, m... Ekologijos terminų aiškinamasis žodynas
Resin moss, spore plants, in which fungi and algae coexist in the body. Fungal cells and algae cells exchange nutrients through assimilation: the former provide water and minerals and receive organic substances from the latter... ... Agricultural dictionary-reference book
Books
- Biology. Plants, bacteria, fungi and lichens. 6th grade, V.P. Viktorov, A.I. Nikishov. The textbook is written in accordance with the mandatory minimum content of biological education and the requirements for the level of preparation of students of the primary (basic) school. It contains the most necessary…
These amazing plants are an example of the mutually beneficial coexistence of fungi and algae, and less commonly, fungi and cyanobacteria. There are even cases where three people coexist: mushrooms (obligatory) and algae + cyanobacteria. Such cohabitations are called obligate symbiosis.
Types of lichens with different characteristics
There are two-component and three-component lichens. Depending on the number of components in them.
Based on the appearance of the thallus (thallus), lichens can be divided into the following groups:
- crustose lichens. The smallest and longest-lived, they grow mainly on stones, rocks, concrete walls, trees, and old fences. They are difficult to separate from the object on which they grow;
- foliose lichens – these associates can no longer be attached with the whole body to the substrate, but only with one edge (outgrowths - rhizoids), are easily separated, and have the appearance of a leaf. They grow on stones, stumps, and objects that have been lying around for a long time, such as rusty iron, glass, slate;
- fruticose lichens most developed. They grow upward (unlike the first two) and have a bushy appearance. They are mainly attached to the ground or trees. They have the form of twigs or threads. They can grow up to 6 – 7 meters.
Based on the internal structure, this symbiosis can be grouped as follows:
- heteromeric - the body of the lichen on a cut is clearly divided into layers of fungus and algae;
- homeomeric - components are randomly mixed inside the thallus.
Based on their place of growth, lichens are divided into:
- epigeic (grows 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? But why: algae need water (moisture) for normal life, and the fungus needs ready-made food - it cannot prepare anything for itself from water and light (as almost all plants do), so it is a heterotroph - it feeds on the products of photosynthesis of algae ( autotrophs) to which it provides moisture. He accumulates it within himself like a sponge.
Where do lichens grow
Probably everyone knows that lichens are the pioneers of the area. Often, in uninhabited territories, due to certain 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 influences, alkaline influences, and even strong ultraviolet irradiation. 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 residents of the northern territories. In the harsh Siberian winters, the lichens Yagel or reindeer moss, Icelandic moss are the main food product for deer, and moose and roe deer also find them under the snow. Many birds use it as bedding in their nests.
There are edible lichens for people too. This is Bryoria Fremont, edible aspicillia. They are especially loved in China and Japan. Icelandic cetraria and lobaria are used for medicinal purposes. Lichens are used everywhere to make dyes, litmus indicators, odor fixatives, and in perfumery.
Thus, it is difficult to exaggerate the importance of such a small and inconspicuous lichen for the biocenosis and food chains. Its only drawback is that it grows on sculptures and monuments, which people have to get rid of, but these are purely human problems; this is not a problem for the rest of the living world.
The relationship that occurs between algae cells and fungal hyphae in a lichen is called symbiosis
One or more algae cells surrounded by fungal hyphae and serving for vegetative propagation are called soredia.
217. Function of the algal layer of lichen:
1. aeration
2. protective
3. assimilating
4. attachment to the substrate
Sample answer: 3
218. Lichens settling on stones:
1. epiphytic
2. epigeic
3. epilithic
Sample answer: 3
219. Function of the lichen core:
1. aeration
2. assimilation
3. protective
4. reproduction
Sample answer:1
220. The classification of lichens is based on:
1. systematic affiliation of the photobiont
2. systematic affiliation of the mycobiont
3. life form
4. anatomical structure.
Sample answer: 2
221. The main method of reproduction of lichens:
1. sexual
2. asexual
3. vegetative
Sample answer: 3
222. During sexual reproduction of a mycobiont, the following are formed on the outside of the lichen:
1. fruiting bodies
2. sporangia
4. media
Sample answer:1
225. Lichen growth rate:
1. 5-10 cm per year
2. 5-10 mm per month
3. 2-3 mm per year
4. 1 cm per year
Sample answer: 3
226. An indicator of severe atmospheric pollution is the growth of lichens of the life form:
1. scale
2. leafy
3. bushy
4. no lichens
Sample answer: 4
227. Largest number species of known lichens have a life form:
1. scale
2. leafy
3. bushy
4. transitional between scale and foliate
Sample answer:1
228. Lichens are an important component of biogeocenoses, since:
1. photosynthesize
2. are “pioneers”
3. participate in the mineralization of organic substances
4. are “long-livers”
Sample answer: 2
229. Representatives of which division do not have a cell wall, the body is plasmodium?
1. slime mold
2. oomycots
3. zygomycotes
4. chytridiomycotes.
Sample answer:1
230. Representatives of this department are called “water molds”:
1. slime mold
2. oomycots
3. chytridiomycotes
4. zygomycotes
Sample answer: 2
231.For all representatives of c. Protoctista is characteristic:
1. absence of the embryo stage in the life cycle.
2. absence of sexual intercourse
3. unicellularity
4. lack of cell wall
Sample answer:1
232. The kingdom Protoctista includes:
1. mushroom-like organisms
2. algae and fungi-like organisms
3. plants, animals, mushrooms
4. lichens
Sample answer: 2
233. Archegonial plants include:
1. higher spore plants
4. mushroom-like organisms
Sample answer:1
234. The predominant generation in the development cycle of bryophytes is...
235. Fruit of cereals:
1. achene
2. winged nut
4. grain
Sample answer: 4
236. Sedge fruit:
3. box
4. lionfish
Sample answer:1
237. An inflorescence with sessile flowers on a common elongated axis is called:
1. earring
3. broom
4. simple ear
Sample answer: 4
238. Family of monocots:
2. Sedges
3. Nightshades
4. Lamiaceae
Sample answer: 2
239. Family with inflorescence spadix in representatives:
2. poppy
3. cloves
4. goosefoot
Sample answer:1
240. Cereals in the Krasnoyarsk Territory:
1. bushes
2. trees
4. subshrubs
Sample answer: 3
241. Species brought from other areas by humans:
1. apophytes
2. colonophytes
3. ergasiophytes
4. Advents
Sample answer: 4
242. Geobotany is the science of
1. lichens
2. plant communities
4. algae
Sample answer: 2
243. The plant community is:
1. biogeocenosis
2. biocenosis
4. phytocenosis
Sample answer: 4
244. Plants of highly saline soils and rocks:
1. xerophytes
2. mesophytes
3. hygrophytes
4. halophytes
Sample answer: 4
245. Leaf succulents:
2. young
3. camel thorn
Sample answer: 2
246. Plants – phanerophytes:
4. tulip.
Sample answer:1
247. The anemophilous line of evolution is characteristic of representatives of the families:
1. Ranunculaceae
2. Sedges
3. Orchids
4. Lilies
Sample answer: 2
248. Establish correspondence:
1. Lamiaceae A. cotton grass
2. Sedge B. jasmine
3. Liliaceae V. corn
4. Cereals G. tulip
1-B,2-A,3-G,4-B
249. The straw stem is characteristic of:
1. sedge
2. cereals
3. orchids
4. lilies
Sample answer: 2
250. Sclerification of the stem is characteristic of the family:
1. sedge
2. Lamiaceae
3. bluegrass
4. asteraceae.
Sample answer: 3
251. Triangular stems are a distinctive feature of the family:
1. bluegrass
2. sedge
3. Lamiaceae
4. asteraceae
Sample answer: 2
252. Unisexual flowers are characteristic of:
1. bluegrass
2. sedge
3. Asteraceae
4. orchids
Sample answer: 2
253. The tepals of the second circle of the Myatlikovy perianth are reduced and are called:
1. bractae
3. lodicules.
Sample answer: 3
254. Intercalary growth is expressed in:
1. bluegrass
2. sedge.
3. ranunculaceae