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, gas exchange changed. The temperature and biochemical conditions became completely different, and the plants successfully adapted to them. Consider 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, the descendants of green algae began to develop land.
Most clearly, such adaptation mechanisms can be traced in mosses. For example, the main condition for the successful propagation 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 that are practically devoid of conductive tissue. Therefore, the size of these living organisms is very small - from 1 mm to 50 cm. Mosses do not have roots, they attach to the surface of the earth with filamentous outgrowths, rhizoids, with which these plants absorb water. Rhizoids sometimes consist of one cell. Unlike the roots of all other plants with multicellular conductive tissue. Other parts of the body of moss can be conditionally defined as a stem and leaves. However, in reality 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. Mossy species are also found in arid areas. The survival of the bryophytes is striking - they can withstand the effects of very high temperatures, up to 70 degrees heat. In a dry climate, mosses have adapted to fall into a state of suspended animation associated with seasonal climatic variations. When it rains and the air temperature drops, the soil is moistened, and the moss “comes to life”, the breeding cycle begins. Consider the meaning of spores in the life cycle of mosses.
Living conditions of mosses
Moss grows safely 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 saline soils near the sea.
Extremely tenacious spores of mosses. With the wind, they can travel great distances. Spores remain viable for decades.
Mosses accumulate significant moisture reserves, so with their help there is a regulation of the water balance of a particular landscape. Therefore, for the ecosystem, moss is extremely important. In addition, for some species of animals, moss is the main food supply.
About 30 thousand species of mosses grow on earth today. Scientists classify these plants according to morphology, structure of spore boxes and methods of distribution of spores.
Mosses are able to reproduce both by spore and vegetatively. In the life cycle of moss, the sexual generation predominates over the asexual.
Deciduous Mosses or Bryopsids
This is a fairly large class of plants, which is represented by 15 thousand species of mosses. They are unusually diverse in appearance, size and shape. This plant is 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 propagation of deciduous mosses is spores. Most often, these plants are found in moist places, in swamps, as well as in the tundra. Kukushkin flax and sphagnum are typical representatives of bryopsids.
Liver mosses
The liverworts are represented by two subclasses: Jungermannium and Marshantium. These plants are also numerous - 8.5 thousand species. Like deciduous mosses, gametophyte is the stage of their greatest viability. The plant itself is a thick stem with leaves that are located along the stem. The method of reproduction is the spores that are distributed using a special device, a sort of "spring", which is called the elater. These plants are well established in humid tropical and temperate climates. Among the representatives are polymorphic marchanthus, ciliary pitlidium, Blepharostroma fibrosus, and others.
Antocerotic Mosses
This class is not so numerous and is represented by 300 species of plants. Sporophyte is the most important life stage in the development cycle of this plant. Antocerotic mosses look like a thallus - this is a body that is not divided into root, stem and leaves. Such mosses grow in tropical humid forests and temperate zones. Antoceros is a typical representative of this class.
The life cycle of cuckoo flax will be described below. Moss cuckoo flax is a perennial plant. Its structure is a fairly developed structure. The primary horizontal stalk is brown in color without leaves and the secondary stalk is erect, 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 transport water and minerals along the stem to the leaves. Its rhizoids are capable of reaching a length of almost 40 cm.
Locations of moss cuckoo flax
Kukushkin flax usually grows well in humid places, in marshes, wet meadows and spruce forests, loves sunlight. In open areas it grows very powerfully, capturing more and more new territories. Its stems so densely “envelop” the soil that the seeds of other plants are not able to germinate. This plant is fond of deforestation or conflagration. This moss absorbs water extremely well. The density of the plant retains moisture in the soil. Thanks to what the bogging of the area occurs.
Since ancient times, people have been using this plant as a heater. Caulk with its help the walls of log houses. Sometimes used as a medicinal plant for colds.
Kukushkin flax is involved in the formation of peat. This is a valuable fertilizer, good raw material for the chemical industry.
Life cycle of moss cuckoo flax
Moss cuckoo flax is a dioecious plant. This phenomenon occurs when on different stems of one plant different-sex organs are formed - female and male.
Kukushkin flax develops by alternating between two generations - asexual and sexual. Sporophyte is the life cycle of mosses, the result of which is 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, germ cells containing only one set of chromosomes - the haploid one.
Now it is clear why in the life cycle of mosses the sexual generation prevails over asexual.
Boxes with spores, according to the people, look like a cuckoo sitting on a pole. On the whole, outwardly, moss cuckoo flax resembles a miniature flax plant, from where it got its name. The thin hairs on the cap covering the spore box are also similar to linen yarn.
The box itself consists of several parts - a urn, a neck and a lid. Inside it is a small column. It just contains infertile cells, from which haploid spores mature as a result of reduction division. The urn ends with a ring. After completion of the ripening process, this ringlet under the blow of wind easily separates the urn and the lid from the stem. Spores fall to the ground, and the important plant life cycle begins again.
Moss Life Cycle Stages
Asexual spores in the process of "maturation" become haploid spores (containing a half set of chromosomes) as a result of indirect, reduction division.
When a haploid spore gets on moist soil, it begins to germinate, forming a protonema - filamentous pregrowth. The gametophyte is formed from it - female or male.
On the tops of various stalks-gametophytes of cuckoo flax, anteridia and archegonia - male and female genital organs develop. In archegonium, the eggs mature, and in anteridia, bicarbonated spermatozoa. Externally, male plants are distinguished by large yellowish-brown leaves at the apex. In female plants, such leaves are absent.
Successful fertilization requires moisture droplets that carry sperm from the anteridia to the archegonia, where the eggs are. This process usually contributes to rain or heavy dew.
As a result of the fusion of the sperm and the egg, a diploid zygote forms 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 mature.
We have considered the sequence of stages in the life cycle of moss.
The structure of moss cuckoo flax
The body of mosses is similar in structure to algae, since it also consists of a thallus. Nevertheless, it may have a structure resembling stems and leaves. Attaches to the soil with the help of rhizoids. These plants are able to absorb water and minerals not only directly by rhizoids, but also by the whole body.
