Life cycle of mosses (cuckoo flax). Development cycle of bryophytes Development cycle of sphagnum moss

Mosses belong to higher plants. Higher plants are multicellular organisms. Their body is divided into tissues and organs: leaves, stems, roots. The reproductive organs of higher plants are multicellular: the female is the archegonium, the male is the antheridium.

There are currently 35,000 species of mosses. Mosses, compared to other higher plants, have the most primitive organization. In the department Bryophytes have a developed sexual generation - the gametophyte, which is primarily a mature moss plant. The asexual generation (sporophyte) is represented in mosses by a sporogon (a capsule on a stalk), which develops on the gametophyte after fertilization.

In lower mosses, the body does not differentiate into vegetative organs, and it is a flat leaf-shaped plate - a thallus, lying on the soil or other substrate, attached to it by thin rhizoids. In higher mosses, the body is divided into organs. Stem-shaped caulidia mosses have conducting tissues: water-conducting cells - hydroids and living cells that conduct organic substances - leptoids, which form a primitive central cylinder - prostel. There are no roots; their function is performed by rhizoids. Moss leaves ( phyllidia) consist of small cells with chloroplasts.

Moss development cycle

Mosses are small plants that cover the soil in more or less dense turf. The development of moss begins with a spore, i.e. from a single-celled, microscopically haploid rudiment. After the spore lands on a moist substrate, a thin, usually branched, green thread or plate of algae grows from it. This small thread (plate) is called protonema. After some time, buds appear on the protonema, giving rise to an adult moss plant. In true mosses, the stem (caulidium) and leaves (phyllidia) are clearly distinguished from each other; The stem is most often covered in the lower part with hairs or rhizoids. The reproductive organs develop at the tops of the main stems or lateral branches: antheridia♂ and archegonia♀, in which germ cells are formed. Sperm develop inside the antheridium, while the archegonium contains the egg. All stages of moss development, starting from the spore and ending with the stem with leaves and reproductive organs, are combined into the concept sexual generation or gametophyte.

Fertilization of an egg by a sperm is accomplished with the help of drops of water inside the archegonium in damp weather; after fertilization, a capsule with sporangium grows on the gametophyte, in which after reduction division disputes are formed. The box sits on a thin stem. This - sporogon moss or asexual generation (sporophyte). By the time the spores ripen, the box opens at the top with a lid and the spores spill out.

Classification of mosses

More advanced mosses belong to Cl. Musci (deciduous).

The body of deciduous mosses is always divided into caulidia (stems) and phyllidia (leaves). The stems have radial symmetry; the leaves are arranged in a dense spiral on the stems. Deciduous mosses are divided into 2 subclasses: Sphagnidae and Bryidae.

Sphagnum mossesSphagnidae

One of the well-separated groups is the sphagnum mosses (Sphagnidae), which include only one family Sphagnaceae and one genus Sphagnum.

The thin and rather long stem of sphagnum is devoid of rhizoids and is densely covered with twigs, arranged in bunches (whorls) of several pieces; Some of these protruding branches are directed more or less perpendicular to the stem, the rest hang down and envelop the stem and are called drooping. At the tip of the stem, young apical branches form a “head” characteristic of sphagnum, where the genital organs are formed. The stem is surrounded on the outside hyalodermis from thin-walled, colorless cells, usually equipped with holes - pores through which plants absorb water. In some species, hyalodermis cells have spiral thickenings inside. Below it are thick-walled cells wood cylinder, often colored brownish. The central part of the stem is occupied by colorless, thin-walled pith cells.

Both the stem and branches of sphagnum are more or less densely covered with leaves. The leaves of the branches never have veins and consist of a single layer of cells. Most of the leaf blade (2/3) is occupied by large dead aquifers hyaline cells equipped with pores and transverse thickenings. Hyaline cells, connecting with each other, form a dense network of capillaries and, like the hyalodermis of the stem, serve to absorb and conduct water. They are capable of accumulating water 30-40 times the weight of the moss itself. Sandwiched between the hyaline cells are very narrow living chlorophyll cells. For accurate identification of sphagnum species, the shape of hyaline and chlorophyll cells, which can be examined in a leaf under a microscope, is of great importance.

Sphagnum mosses growing in raised bogs have brown and red shades due to stagnant moisture. In swampy forests and low-lying swamps with flowing moisture, mosses have a green or brown-green body color.

Green mosses (s/cl.Bryidae)

These include 13,500 species. Green mosses are extremely widespread on Earth, especially in temperate and cold latitudes. Green mosses take a large part in the composition of the Earth's vegetation cover. They form continuous covers in swamps (mainly lowland ones), in coniferous forests, meadows, and tundras.

Green mosses are characterized by a developed filamentous, abundantly branched protonema. The sporogon develops in the capsule peristome- a special apparatus that ensures uniform and gradual dispersion of spores. Mosses of the sub-class Bryidae have a complex structure. The leaves are multi-layered with a pronounced vein. The stems have a conducting cylinder - prostel. The bed is surrounded by bark with leaf traces. Reproductive organs develop at the top of one plant or on different ones. If the archegonia develop at the top of the main stem, then the mosses are apical (Acrocarpi), if on the side of the stem, then they are side-bearing (Pleurocarpi).

In the former, after fertilization, the sporogon develops at the top of the main stem or lateral shoot, after which the stem stops growing, in the latter, the sporogon develops on the side of the stem and the main axis continues to grow. Side-bearing mosses have “pinnate” branching, while top-carrying mosses have monopodial branching with weak development of lateral branches.

The sporogon of green mosses has a cap at the top of the capsule - calyptra(remnant of the archegonium's abdomen). A peristome and sporangium with spores develop in the sporogon capsule. After maturation, the sporangium wall is destroyed and the spores end up directly in the capsule. The teeth of the peristome hermetically close the holes in the box, and in dry weather they straighten and spores are sown through the holes when the box is rocked, preventing the germination of spores inside the box.

The importance of mosses in nature is that they, like lichens, are pioneers in the colonization of new territories, abundant in the ground cover of many types of forest. Peat is formed in swamps, which is both a fertilizer and an important energy material. Aquatic mosses form a soft substrate on which fish lay their eggs; in it, fish fry find food and protection. Along with their positive value, mosses cause harm, causing waterlogging of forests, meadows, and pastures.

Many mosses form erect, unbranched shoots, collected into dense turf or cushions. Others, strongly branching, spread along the soil or other substrates, such as tree bark or rocks. The height of the shoots usually does not exceed 5 cm. The leaf arrangement is spiral; there are no roots, and their function is performed by rhizoids.

"Stem".

Mosses do not have true stems and leaves, and the corresponding structures are designated by special terms: caulidia and phyllidia (phylloids). In many mosses, the caulidium cells are undifferentiated, while in others there is a central cord of thick-walled cells. They undoubtedly perform a supporting function, but are not equivalent to the conductive system - specialized tissues that serve for the transport of water and nutrients in vascular plants. Most of the water and salts necessary for the life of mosses are drawn into their body from the external environment by capillary forces through the gaps between the phyllidia and caulidium.

"Leaves".

Phyllidias come in different shapes and sizes. Usually they consist of only one layer of cells, but in some species there are several of these layers along the edges of the phyllidium. If a midrib several cells thick is present, it may be single, reaching the apex of the phyllidium, or double and short. In some species, lamellar or columnar outgrowths are formed on it. The shape of the phyllidium can be round, oval, lanceolate, oblong or linear, and its edge can be solid or jagged, flat or rolled. These characters are quite species-specific and are used in taxonomy.

Rhizoids.

The role of roots is played by multicellular branching threads called rhizoids. In young mosses, they absorb water from the soil with minerals dissolved in it, but over time they lose this ability and simply serve to anchor the plant in the substrate.

Life cycle.

The green photosynthetic plant in mosses is the sexual generation called the gametophyte. Gametes, i.e. germ cells are formed on it in special genital organs (gametangia). The male gametangium is called antheridium, the female gametangium is called archegonium. From the fertilized egg (zygote), the spore generation, the sporophyte, develops. In mosses, it is practically devoid of chlorophyll, remains attached to the gametophyte and receives nutrition from it. In a sporophyte, each cell contains a double (diploid) set of chromosomes, while in a gametophyte, each cell contains a single (haploid) set, as in gametes. When a sperm fuses with an egg, one diploid set is formed from two haploid sets, which is necessary for the development of the sporophyte. In the latter, when a dispute is formed, the so-called reduction cell division (meiosis), each spore again becomes haploid and can germinate into the same haploid gametophyte.

Gametophyte.

When a spore lands in a damp place, it first develops into a branched multicellular filament called a protonema, or seedling. The protonema branches remaining on the surface become green and photosynthetic, while those that penetrate the soil become colorless rhizoids. On the green parts of the seedling, lateral buds form, from which leafy shoots develop. One spore can produce an entire colony of gametophytes. In some species, the seedlings are long-lived, sometimes covering several square decimeters of soil, in others they are small, disappearing after the appearance of leafy shoots.

Gametangia are formed terminally, i.e. on the tops of the main or side shoots. Antheridia and oogonia are either on the same branch or on different ones (sometimes even on different plants) and are surrounded by sterile threads called paraphyses. The antheridium is a spherical or cylindrical multicellular sac, the internal cells of which produce two motile biflagellate sperm. Archegonium is a multicellular flask-shaped structure. At its base (abdomen) there is a single egg, and the “neck” (neck) is filled with the so-called. tubular cells, which are destroyed during puberty, turning into a substance that attracts sperm. In order for them to enter the archegonia and fertilization to occur, droplet-liquid moisture, such as rain or dew, is necessary. The antheridium bursts, releasing sperm. They swim to the neck of the archegonium, penetrate its canal, and one of them fuses with the egg, forming a diploid zygote.

Sporophyte.

The zygote begins to divide in the archegonium, which grows for some time along with the developing sporophyte. When it becomes visible to the naked eye, it consists of three parts: a foot embedded in the abdomen of the archegonium, a thin stalk - the sporophore, and a capsule where the spores ripen. The growing sporophyte breaks the archegonium in a circle and carries its upper part upward in the form of a cap (calyptra) covering the capsule. A typical mature capsule is a complex structure consisting of an urn, a lid and a layer of specialized thick-walled cells connecting them - a ring. Swelling with water, the ring separates from the adjacent parts of the box and the lid falls off, revealing the mouth of the urn, which can be smooth or surrounded by a peristome (peritome) of one or two concentric rows of denticles. These teeth are either flat or bear from 4 to 64 transverse hygroscopic thickenings. Their number and shape are important taxonomic characteristics of mosses.

The mature capsule contains many free spores. They are blown out or shaken out from there, carried by wind, water or animals and, once in favorable conditions, germinate.

Alternation of generations and evolution.

The alternation in the life cycle of a diploid sporophyte and a haploid gametophyte is called a change of generations. It is observed in all plants, however, if in mosses the gametophyte is a clearly visible green individual, in representatives of all other departments of this kingdom it is reduced to a miniature short-lived “thallus”, sometimes not even capable of photosynthesis, or even to a group of cells inside the sporophyte. Thus, mosses are a very specialized branch of evolution, related by origin to some algae and, most likely, did not give rise to any group of “higher” ones, i.e. vascular, plants. See also PLANT SYSTEMATICS.

Mosses belong to the department of higher plants and are small-sized organisms that are poorly adapted to life on land.

Only a small number of bryophytes living in water reach a length of more than 50 cm.

Bryophyte department

Mosses, or bryophytes, are one of the oldest forms of plant life on Earth. There is an opinion that the ancestors of mosses were ancient extinct plants - psilophytes.

And the first finds of bryophytes date back to the Carboniferous.

According to scientists, the number of species is approximately 20 thousand.

The main characteristics of these plants: the presence of stems and leaves, the absence of a root system. Mosses are ubiquitous in areas with high humidity.

They are studied by scientists called bryologists, and the science of studying bryophytes is bryology.

Moss structure

Bryophytes are multicellular plants whose body consists of leaves and stems or belong to thallous forms. There are no roots.

Attachment of organisms to the surface is carried out using rhizoids. But there are plants that do not have structures that act as roots.

The structure of mosses is relatively simple. Their body consists of main or assimilative tissue, including chloroplasts, and integumentary, storage, mechanical, and conductive tissues.

Moss development cycle

Mosses are plants whose development is associated with regression of the sporophyte and superiority of the gametophyte. And this serves as a feature that unites different types of bryophytes.

The sporophyte includes a capsule and a stalk, the expanding part of which penetrates into the tissue of the gametophyte. In this way, the sporophyte is nourished.

The sporophyte is necessary for the formation of spores that germinate in a favorable environment. As soon as the spore grows, the gametophyte matures. The growth of the protonema begins, which is a filamentous or lamellar formation.

Buds appear on the protonema, from which lamellar thalli or leaf-stem shoots are formed. This is followed by the development of sexual reproductive organs (gametangia), female genital organs - archegonia and male genital organs - antheridia.

Moss propagation

Mosses reproduce using spores. The reproductive organ is the sporogon. The process diagram is simple. On the developing protonema, rhizoids appear, which serve for attachment to the surface, and buds. From the buds, new organisms called gametophytes mature.

Mosses with male and female reproductive organs on the same plant organism are called monoecious.

Dioecious bryophytes are separately growing shoots of antheridia and archegonia. Gametangia form separate groups. For fertilization, drops of water falling from the antheridium onto the female shoot are sufficient.

A zygote appears inside the archegonia, and after about 12 months a sporophyte is formed. The sporophyte on a moss plant can be seen in spring or early summer. It looks like a reddish-brown pin.

Leafy bryophytes reproduce vegetatively. Under favorable conditions, the torn parts of the stem with leaves are attached to the base by rhizoids and begin to grow independently.

Types of mosses with names and photos

The modern classification of bryophytes, based primarily on the external structure, distinguishes 3 classes. Below is a brief description and examples of the main bryophytes:

The importance of mosses in nature and human life

The role of mosses in nature and human life is very important. The areas of use are diverse. Mosses serve as a source of food for animals and are sources of photosynthesis.

Peat, formed from bryophytes, is used for the production of flammable substances, methanol, paraffin and dyes. Some varieties of plants are used in the cosmetics industry and mud therapy.

Bryophytes serve to protect soils from erosion and help regulate water balance.

Mosses are unique plants in their diversity, the study of which reveals various interesting facts:

In order to occupy new spaces, ancient plants had to adapt to completely new living conditions. For example, the constant loss of moisture through evaporation contributed to the appearance of a protective waxy layer. The lack of support in the air, unlike water, caused the formation of a fairly rigid body, the principle of plant respiration and gas exchange changed. The temperature and biochemical conditions became completely different, and the plants successfully adapted to them. Let's look at the life cycle of mosses in this article.

What is moss?

Mosses are a group of ancient organisms. According to some assumptions, they are the ancestors of existing land plants. Water on our planet is the source of life, in which all living things, including plants, originated. About 420 million years ago, descendants of green algae began to colonize land.

The proliferation of algae is the presence of water. Mosses can also reproduce only with the help of moisture.

The life cycle of mosses is very interesting. Of the entire group of higher plants, they are the most primitive organisms. Bryophyta or bryophytes are multicellular plants with virtually no conducting tissue. Therefore, the sizes of these living organisms are very small - from 1 mm to 50 cm. Mosses do not have roots; they are attached to the surface of the earth by thread-like outgrowths, rhizoids, with which these plants absorb water. Rhizoids sometimes consist of one cell. Unlike the roots of all other plants, which have multicellular conducting tissue. Other parts of the moss body can be roughly defined as the stem and leaves. However, in fact, they are completely different from the stems and leaves of all other plants on the planet in their structure.

Where do they meet?

Mosses have successfully adapted to life in a wide variety of temperature and climatic conditions and are distributed almost throughout the planet: from the polar regions to the tropics. They thrive in conditions of high air humidity - in forests and mountains. Mosses are also found in dry areas. The survival rate of bryophytes is amazing - they can withstand very high temperatures, up to 70 degrees Celsius. In dry climates, mosses have adapted to enter a state of suspended animation associated with seasonal climatic fluctuations. When the rains fall and the air temperature drops, the soil becomes moist and the moss “comes to life”, the reproduction cycle begins. Let's consider the importance of spores in the life cycle of mosses.

Living conditions of mosses

Moss grows happily in places with a lack of sunlight, for example, in caves, cracks and crevices of rock, occupying those ecological niches where other plants cannot exist.

The only place where mosses are unable to exist is in saline soils near the sea.

Moss spores are unusually tenacious. With the wind they can travel great distances. The spores remain viable for decades.

Mosses accumulate significant reserves of moisture, so they help regulate the water balance of a particular landscape. Therefore, moss is extremely important for the ecosystem. In addition, for some animal species, moss is the main food source.

About 30 thousand species of mosses grow on earth today. Scientists classify these plants according to their morphology, the structure of the spore capsules, and the methods of spore distribution.

Mosses are able to reproduce both by spores and by vegetative means. In the life cycle of moss, the sexual generation predominates over the asexual one.

Deciduous mosses or bryopsids

This is a fairly numerous class of plants, which is represented by 15 thousand species of mosses. They are incredibly varied in appearance, size and shape. This plant consists of a stem covered with leaves that are arranged in a spiral around the stem. The most vital stage of their development is called the gametophyte. The method of reproduction of deciduous mosses is through spores. Most often, these plants are found in damp places, swamps, and also in the tundra. Kukushkin flax and sphagnum are typical representatives of bryopsids.

Liver mosses

Liverworts are represented by two subclasses: Jungermanniaceae and Marchantiaceae. These plants are also numerous - 8.5 thousand species. Just like in deciduous mosses, the gametophyte is the stage of their greatest vitality. The plant itself is a thick stem with leaves that are located along the stem. The method of reproduction is spores, which are spread using a special device, a kind of “spring” called elatera. These plants do well in humid tropical and temperate climates. Among the representatives are marchantia polymorpha, ptilidium ciliata, blepharostroma pilafolium, and others.

Anthocerotic mosses

This class is not so numerous and is represented by 300 plant species. The sporophyte is the most important life stage in the development cycle of this plant. Anthocerote mosses look like a thallus - this is a body that is not divided into roots, stems and leaves. Such mosses grow in tropical rainforests and temperate climate zones. Antoceros is a typical representative of this class.

The life cycle of cuckoo flax will be described below. Cuckoo flax moss is a perennial plant. Its structure is a fairly developed structure. The primary horizontal stem is brown without leaves and the secondary stem is erect, branched or single.

The secondary stem is covered with dark green, harsh, awl-like leaves. These stems can reach a height of 10-15 to 40 cm. The lower leaves are scales. The plant has a primitive conducting system that is capable of moving water and minerals along the stem to the leaves. Its rhizoids can reach a length of almost 40 cm.

Places where cuckoo flax moss grows

Kukushkin flax usually grows well in damp places, in swamps, damp meadows and spruce forests, and loves sunlight. In open areas it grows very powerfully, capturing more and more new territories. Its stems “envelop” the soil so tightly that seeds of other plants are unable to germinate. This plant loves cleared forests or fires. This moss absorbs water extremely well. The density of the plant retains moisture in the soil. Due to this, the area becomes swamped.

People have long used this plant as insulation. They use it to caulk the walls of log houses. Sometimes used as a medicinal plant for colds.

Kukushkin flax participates in the formation of peat. It is a valuable fertilizer and a good raw material for the chemical industry.

Life cycle of cuckoo flax moss

Cuckoo flax moss is a dioecious plant. This is a phenomenon when different-sex organs - female and male - are formed on separate stems of one plant.

Kukushkin flax develops by alternating two generations - asexual and sexual. Sporophyte is the life cycle of mosses that results in the formation of asexual cells. They contain a diploid set of chromosomes. Gametophyte is another life cycle of the same plant, which ends with the formation of gametes, sex cells containing only one set of chromosomes - haploid.

Now it is clear why the sexual generation predominates over the asexual generation in the life cycle of mosses.

Spore boxes are popularly believed to look like a cuckoo sitting on a pole. In general, the appearance of cuckoo flax moss resembles a miniature flax plant, which is where it got its name. The fine hairs on the cap covering the spore capsule are also similar to linen yarn.

The box itself consists of several parts - an urn, a neck and a lid. There is a small column inside it. It contains infertile cells, from which haploid spores mature as a result of reduction division. The urn ends with a ring. After the ripening process is completed, this ring easily separates the urn and cap from the stem under a blow of wind. The spores fall to the ground and the important life cycle of the plant begins again.

Moss life cycle stages

Asexual spores in the process of “maturation” become haploid spores (containing half the set of chromosomes) as a result of indirect, reduction division.

When a haploid spore lands on moist soil, it begins to germinate, forming a protonema - a filamentous precursor. A gametophyte is formed from it - female or male.

At the tops of various gametophyte stalks of cuckoo flax, antheridia and archegonia develop - male and female reproductive organs. Oocytes mature in archegonia, and biflagellate spermatozoa mature in antheridia. Externally, male plants are distinguished by large yellowish-brown leaves at the top. Female plants do not have such leaves.

Successful fertilization requires drops of moisture that transport sperm from the antheridia to the archegonia, where the eggs are located. This process is usually facilitated by rain or heavy dew.

As a result of the fusion of sperm and egg, a diploid zygote is formed at the top of the female plant. From it grows a new generation of this plant, a sporophyte or sporogon. And it is a sporangium box in which spores ripen.

We examined the sequence of stages of the moss life cycle.

The structure of cuckoo flax moss

The body of mosses is similar in structure to algae, since it also consists of a thallus. However, it may have a structure resembling stems and leaves. Attached to the soil using rhizoids. These plants are able to absorb water and minerals not only directly through the rhizoids, but throughout the body.

The value of moss in nature

In general, mosses are an essential component of the ecological system of our planet. The life cycle of mosses differs from that of other higher plants. They survive well in nutrient-poor soils. They inhabit places that have been subjected to adverse anthropogenic impacts. Thus preparing the land for restoration. After all, when moss dies, it forms a useful soil substrate on which other plants will subsequently grow.

Mosses are indicators of environmental pollution, in particular the atmosphere. Because some types of mosses do not grow in places where the concentration of sulfur dioxide in the air is exceeded. The absence of certain types of mosses in traditional habitats can also indicate air pollution. However, mosses also indicate changes in soils, and much more.

Mosses protect the fragile balance in permafrost areas, covering the soil from the sun's rays. Thus maintaining ecological balance.

Now, if you are asked: “Characterize the life cycle of moss,” then you can easily do it.

The value of sphagnum in nature is very large. This moss creates a swamp, does not live on it, like many other representatives of the flora, but creates. Peat reserves are also formed from this plant, which is a very valuable natural material. It has many features and, thanks to this, is very widely used in medicine. Recently, the scope of its use has been increasing.

Classmates

Sphagnum since ancient times used in construction just like cuckoo flax. It is used to insulate the walls of wooden buildings. But this plant should not be confused with white moss, which is formed from dry pine trees.

Where does moss grow?

It would be more correct to talk about groups of mosses rather than one species. In each area you can find several varieties. The structural features of all species are very similar, as are living conditions and appearance. They can only differ in color: green, brown and reddish.

This type of forest dweller mainly grows in transitional and raised swamps, in forests that are swampy or just beginning to become swampy, and is also found in lowlands where water accumulates.

Appearance of a forest dweller

Sphagnum, protruding- this inhabitant of swamps has an erect and long stem. The stem has protruding side branches that are covered with small leaves with scales. There are also leaves on the stem, but there are much fewer of them.

The top forms a head, since the branches on it are twisted. It is the tip that is the hallmark of sphagnum species. On the head there are separate branches on which there are organs with sex cells, they are called antheridia, they contain sperm and archegonia with eggs.

The life cycle of the sphagnum moss plant is very similar to that of other species of such plants. Hematophyte plant forms sex cells. After the cells merge, a sporogon is obtained; in place of the egg, it has a capsule where the spores ripen. When the spore germinates, a new hematophyte is formed.

The top is constantly growing, and its lower part is dying off; it is always moving upward, closer to the light. And the part that dies, over time, turns into peat.

Only the tip of the shoot is green, and the part that is located below is whitish, since it is constantly immersed in water. And below the whitish part is a light brown part.

Forest sphagnum has no roots; they are replaced by thin threads called rhizoids. It does not need roots, since it is almost constantly in water, and its entire surface absorbs it. And during drought or when there is simply not enough water, the plant can actively stock up on it.

If you look at sphagnum under a microscope, you can see that not all plant cells are filled with living content. A large number of cells are dead and have pores that connect to the external environment. Thanks to these dead cells, the moss stores water, the amount of stored water can be twenty times the weight of the plant itself.

It is through this that the plant got its name, “sphagnos” - translated from Greek means sponge. And its second name appeared because when the plant completely dries out from water, it turns white.

Application

Sphagnum is used in:

• Medicine.
• Tourism.
• Gardening and for indoor plants.
• Construction.

It must be laid as follows. You need to take a small bunch of sphagnum and loosen it a little and only then put it on the logs, after laying it you need to press it a little with your palm. The next bunch of plants is placed so that the previous bunch is covered. The thickness of the moss should be no less than one and a half centimeters.