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 wax 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. Consider in this article the life cycle of mosses.
What is moss?
Mosses are a group of ancient organisms. According to some assumptions, they are the ancestors of the currently 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, the descendants of green algae began to explore the land.
Mosses can most clearly trace such adaptation mechanisms. For example, the main condition for the successful reproduction 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 primitiveorganisms. Bryophyta or bryophytes are multicellular plants that are practically devoid of conductive tissue. Therefore, the sizes of these living organisms are quite small - from 1 mm to 50 cm. Mosses have no roots, they are attached to the surface of the earth with filamentous outgrowths, rhizoids, with which these plants absorb water. Rhizoids sometimes consist of a single cell. Unlike the roots of all other plants that have multicellular conductive tissue. Other parts of the body of the moss can be loosely 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 variety of temperature and climatic conditions and are distributed almost throughout the planet: from the polar regions to the tropics. They perfectly exist in conditions of high humidity - in forests, mountains. Mosses are also found in arid regions. The survival rate of bryophytes is amazing - they can withstand exposure to very high temperatures, up to 70 degrees Celsius. In a dry climate, mosses have adapted to fall into a state of suspended animation associated with seasonal climatic fluctuations. When the rains fall and the air temperature drops, the soil is moistened, and the moss "comes to life", the reproduction cycle begins. Consider the importance of spores in the life cycle of mosses.
Moss living conditions
Moss thrives in areas with little sunlight, such as caves, crevices and crevices in rock,occupying those ecological niches where other plants cannot exist.
The only place where mosses cannot exist is in saline soils near the sea.
Moss spores are extremely tenacious. With the wind, they can travel great distances. 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 species of animals, moss is the main food supply.
On the ground today there are about 30 thousand species of mosses. Scientists classify these plants according to their morphology, the structure of the spore pods, and how the spores are dispersed.
Mosses are able to reproduce both with the help of spores and vegetatively. In the life cycle of moss, the sexual generation predominates over the asexual one.
Decidated mosses or bryopsides
This is a fairly numerous class of plants, which is represented by 15 thousand species of mosses. They are extremely diverse in appearance, size and shape. This plant is a stem covered with leaves that spiral around the stem. The most vital stage of their development is called the gametophyte. The mode of reproduction of deciduous mosses is spores. Most often, these plants are found in wet places, in swamps, as well as in the tundra. Kukushkin flax and sphagnum are typical representatives of briopsids.
Liver mosses
Liverworts presentedtwo subclasses: Jungermannian and Marchantian. These plants are also numerous - 8.5 thousand species. Just like in deciduous mosses, the gametophyte is the stage of their greatest viability. The plant itself is a thick stem with leaves that are arranged along the stem. The method of reproduction is spores that spread with the help of a special device, a sort of "spring" called elatera. These plants are well established in humid tropical and temperate climates. Among the representatives are polymorphic marchantia, ciliated ptylidium, hairy blepharostroma, and others.
Anthocerotus mosses
This class is not so numerous and is represented by 300 plant species. The sporophyte is the most important life stage in the life cycle of this plant. Anthocerotus mosses look like a thallus - this is a body that is not divided into root, stem and leaves. Such mosses grow in tropical rainforests and temperate zones. Anthoceros is a typical representative of this class.
The life cycle of the cuckoo flax will be described below. Moss cuckoo flax is a perennial plant. Its structure is a fairly developed structure. The primary horizontal stem is brown without leaves and the secondary stem is upright, branched or solitary.
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 conductive system that is able to move water andminerals along the stem to the leaves. Its rhizoids are capable of reaching a length of almost 40 cm.
Places of moss cuckoo flax
Kukushkin flax usually grows well in damp places, in swamps, damp meadows and spruce forests, loves sunlight. In open areas it grows very powerfully, capturing more and more new territories. Its stems “envelop” the soil so tightly that the seeds of other plants are not able to germinate. This plant takes a fancy to clearings in forests or conflagrations. This moss absorbs water extremely well. Plant density retains moisture in the soil. Due to which the area becomes swampy.
People have long used this plant as a heater. Caulk with it the walls of log houses. Sometimes used as a medicinal plant for colds.
Kukushkin flax is involved in the formation of peat. It is a valuable fertilizer, a good raw material for the chemical industry.
Cuckoo flax moss life cycle
Cuckoo flax moss is a dioecious plant. This is a phenomenon when different-sex organs are formed on separate stems of one plant - female and male.
Kukushkin flax develops by alternating two generations - asexual and sexual. The sporophyte is the life cycle of mosses that results in the formation of asexual cells. They contain a diploid set of chromosomes. Gametophyte - another life cycle of the same plant, which ends with the formation of gametes, sexualcells containing only one set of chromosomes - haploid.
Now it is clear why the sexual generation prevails over the asexual generation in the life cycle of mosses.
Boxes with spores, according to the people, look like a cuckoo sitting on a pole. In general, cuckoo flax moss looks like a miniature flax plant, from which it got its name. The fine hairs on the cap that covers the spore box also look like linen yarn.
The box itself consists of several parts - an urn, a neck and a lid. Inside it is a small column. It just contains sterile cells, from which, as a result of reduction division, haploid spores ripen. The urn ends with a ring. After the ripening process is completed, this ringlet easily separates the urn and the lid from the stem under the breath of the wind. The spores fall to the ground and the plant's important life cycle 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, reductional division.
When a haploid spore falls on moist soil, it begins to germinate, forming a protonema - a filamentous pregrowth. It forms a gametophyte - female or male.
Antheridia and archegonia, the male and female reproductive organs, develop on the tops of different stalks-gametophytes of the cuckoo flax. In the archegonium, eggs mature, and in the antheridium, biflagellated spermatozoa. Outwardly maleplants are distinguished by large yellowish-brown leaves at the top. Female plants lack such leaves.
Successful fertilization requires drops of moisture that carry sperm from the antheridium to the archegonium 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, sporophyte or sporogon. And it is a sporangium box in which spores ripen.
We have considered the sequence of stages of the moss life cycle.
The structure of moss cuckoo flax
The body of mosses is similar in structure to algae, since it also consists of thallus. However, it may have a structure resembling stems and leaves. It is attached to the soil with the help of rhizoids. These plants are able to absorb water and minerals not only directly by the rhizoids, but also by the whole body.
The value of moss in nature
In general, mosses are the most important component of the ecological system of our planet. The life cycle of mosses is different from that of other higher plants. They do well in nutrient-poor soils. They inhabit those places that have undergone adverse anthropogenic impacts. Thus preparing the earth for restoration. After all, dying, moss forms a useful soil substrate, on which other plants will subsequently grow.
Mosses are indicatorsenvironmental pollution, in particular, the atmosphere. Since 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 moss in traditional habitats can also be used to judge atmospheric pollution. However, mosses also indicate changes in soils, and much more.
Mosses protect the delicate balance in permafrost areas, covering the soil from the sun's rays. Thus maintaining the ecological balance.
Now, if you are asked: "Describe the life cycle of moss", then you can easily do it.
