Plauna, horsetail, ferns represent the group of the first land plants. Despite the fact that they arose more than 400 million years ago, these plants have received sufficient distribution in the modern period. The structure of the plunders, horsetails and ferns, the features of their vital functions and biological significance will be considered in our article.
Landing of plants
There is a theory that all living organisms, including plants, arose in the aquatic environment. The first of these were algae. Over time, environmental conditions have changed significantly, and algae had to adapt to long periods of drought. As a result, they gave rise to the first land plants. Even in the school course of botany, ferns, horsetails, and lice (6th grade) are considered as immigrants to land.
The extinct group of the first land plants are representatives of the rhinophyte department. Their low shoots were devoid of leaves and forked forks. Instead of roots, rhinophytes had rhizoids, with the help of which they were attached to the substrate.
Caps, horsetails, ferns - the highest spore plants
Modern spore plants have a more complex and perfect structure. Plaunas, horsetails, ferns, like all representatives of this systematic group, are formed by real tissues. Thanks to their appearance, the plants became possible to land. Tissues form organs: root and shoot. This is their main difference from lower plants, which are composed of non-specialized cells.
Reproduction of these organisms occurs with the help of asexual reproduction cells - spores. Once in the soil, they germinate.
Life cycle concept
All higher spore plants have a complex life cycle. This is the period between two identical phases of development. It is he who provides the continuity of life of a particular biological species. In the life cycle of spore plants, an alternation of generations is observed - sexual and asexual. Sometimes they differ from each other externally.
The plant on which spores form is an asexual generation. It is predominant in bryophytes. An individual of the sexual generation - a gametophyte, grows out of a spore. The main differences between plunders, horsetails and ferns are its predominance.
Consider each of the departments of higher spore plants in more detail.
Department
These are evergreen herbaceous plants that grow in humid places. In most cases, they are perennial. The crowns have creeping stems that fork forks. Small leaves are attached to them in a spiral.
The root system is formed by additional roots extending directly from the stems. In the area of the tops of the shoots there are scales, which are modified leaves. On them are organs of asexual reproduction - sporangia.
Features of the structure of horsetail
Modern types of horsetail are also perennial herbaceous plants. Their characteristic feature is a clear division of the shoot into nodes to which the toothlike leaves are attached. At the base, they grow together, forming a kind of vagina. The nodes are the cells of the educational tissue, due to which there is an insertion growth of horsetails in height. The underground organ of horsetail is the rhizome, also divided into internodes. The function of photosynthesis in these plants is performed by the ribbed stem. Inside it there are many cavities filled with water and oxygen.
Horsetail sporophyte is a green shoot that looks like small young pine trees. A gametophyte exists separately and has the form of a green plate. One of the most common types of this department - horsetail - has two types of shoots. The first is also called spring, it is not able to carry out photosynthesis and carries spore-bearing spikelets. Summer, green, - vegetative.
General characteristics of fern-shaped
What is the difference between ferns and horsetails? The answer is obvious. This department is the most numerous and diverse, and its modern representatives have a more complex structure in comparison with horsetails and mocks. Among the 10 thousand species that grow at this time, there are herbs, shrubs, and trees.
The group of equine spore ferns is represented by aquatic inhabitants - it is a floating salvinia and four-leafed marsilia. They freely adhere to the surface of water bodies with a small current. In the tropics, an aqueous azoll fern is common, which forms a symbiosis with cyanobacteria that can absorb atmospheric nitrogen.
Miscellaneous ferns grow in moist and shady forests. Their typical representatives are the common bracken, the male thyroid, the female coder, and other species.
It is about such plants that an amazing legend goes that if a fern flower is found on Ivan Kupala on the night, it will be endowed with an amazing gift - it will learn to understand the language of all living beings. However, from the point of view of biology, this is impossible. Higher spore plants, including ferns, do not form flowers and fruits.
How a person uses horsetails, plunders and ferns
Higher spore plants have long occupied their niche in nature and human life. Ferns are part of a large number of plant communities; they are used to decorate landscapes and as medicinal plants. But the most important role of these plants in nature is the formation of a valuable mineral - coal.
In antiquity, all spore trees were gigantic trees. Dying, their trunks in conditions of lack of oxygen and high pressure layers of the earth turned into coal.
How a person uses horsetails, crowns and ferns, can easily be represented by the example of medicine. All of them are valuable medicinal plants. For example, horsetail has a hemostatic and diuretic effect. One of the representatives of the submersible department - the common ram - is used as a means to combat alcoholism.
Spores of these plants have long been used for the manufacture of pyrotechnic products. In the pharmaceutical industry, cocks are also used to sprinkle tablets and to make baby powder.
The main value of higher spore plants is still in the formation of coal. This valuable mineral has long been an important source of energy, since it burns a large amount of heat. The power industry of many countries is based on this raw material.
Thus, plunders, horsetails, ferns are a group of higher spore plants, which is widely represented by fossil and ancient species. They are the first people to come to land, which became possible due to the appearance of more progressive structural features: tissues and organs.