Leafy mosses, representatives, photos and structural features of which will be discussed in our article, belong to higher spore plants. These ancient organisms play a significant role in the cover of our planet.
Leaf mosses: characteristics of the systematic group
These plants are the highest. These are the first land migrants, therefore, in the course of the development of this new habitat, they have developed new signs. First of all, this is a leafy structure and the presence of mechanical and conductive tissues. Such features contribute to a more efficient flow of the photosynthesis process. Leafy mosses, whose structure is much more complicated than algae, have rhizoids instead of roots. This trait "got" them from the lower plants.
Bryophyte diversity
According to the peculiarities of the structure of the aerial parts, mosses can be divided into two groups: thallus and leafy. A typical representative of the first of them is changeable marchantia. This plant has a dichotomously branched thallus darkgreen with brood baskets. Leafy mosses are more common in nature. Their example is the cuckoo flax, which is also called the ordinary polytrich. All sphagnum (white) mosses also have a branched shoot.
What is the life cycle
Leafy mosses are perennial plants. During their life there is a clear alternation of generations. This is the essence of their life cycle. Both generations differ not only in the features of the external structure, but also in the method of reproduction. This feature of vital activity is characteristic of all representatives of higher spore plants. Moreover, in ferns, horsetails and club mosses, the sporophyte predominates in the life cycle, while in mosses, the sexual generation.
Gametophyte
Leafy mosses, whose representatives are shown in the photo, we are used to seeing as a solid green carpet. This is the sexual generation of plants. If you look at it closer, you can see that it consists of small stems with small sessile leaves of a linear type. Like all mosses, they are attached to the substrate by rhizoids. On the shoots of leaf mosses, gametangia are formed, in which germ cells are formed. In the presence of water, they merge, forming an asexual generation of mosses - the sporophyte.
Sporophyte
The asexual generation of mosses develops on a green gametophyte. It looks like a thin leg on which the box is located. Inside it, spores develop - cells of asexualbreeding. When the capsule opens, they enter the soil, germinate and re-form the gametophyte that dominates the life cycle of moss plants. Next, the sexual generation forms a zygote, which divides by meiosis and forms spores. And so the life cycle is carried out again. The sporophyte is incapable of self-feeding, since it practically does not contain chlorophyll in its cells. That is why it is attached to the leaf-stemmed gametophyte, due to which it feeds. These generations also differ in the chromosome set. The sporophyte is diploid. But the sexual generation has a single set, since the germ cells merge during the formation of the zygote.
Leaf mosses: habitat
Mosses always live in damp places. And this is no coincidence. The fact is that the process of fusion of gametes in these plants occurs only with the help of water. Wet forests, mountainous areas, caves, swamps, tree trunks, roofs, damp basements and rooms, darkened walls of houses … Mosses have mastered all these habitats. These plants are excellent at absorbing and retaining water. Therefore, their appearance in the natural environment indicates the swamping of the territory. Bryophytes react very painfully to a decrease in the amount of moisture. In its absence, they can dry out, while maintaining viability. When the humidity returns to normal, they absorb it with the whole shoot and again move on to normal existence. Due to this ability, leafy mosses are more adapted to changing living conditions. Their wide distribution is also facilitated by the fact that animals do not eat them, do not damage bacteria and fungi. This is because, together with water, they absorb poisonous and radioactive substances.
Meaning of mosses
Leaf mosses, primarily sphagnum mosses, play a major role in the process of waterlogging and the formation of peat, which is a valuable fuel mineral, fertilizer, raw material for the production of alcohols, plastics, acetic acid, naphthalene, and insulating materials. The process of formation of this substance is quite long in duration: 1 cm of peat is formed for as long as 10 years. Absorbing moisture, leafy mosses are regulators of the water balance of the soil, protect it from erosion. However, at the same time, the spread and growth of mosses impairs its gas exchange. As a result, plants do not receive oxygen, die off, and the process of their decay begins.
So, leafy mosses are the most numerous representatives of this department, which are most adapted to changes in environmental conditions. They are able to absorb moisture with the entire surface of the shoot, holding it for a long time. The life cycle of these plants is dominated by the gametophyte. An asexual generation develops on it, which reproduces with the help of spores.
