The structure of the fern. Features of the fern structure

Ferns are an ancient group of higher spore plants, which played a major role in the processes of formation of coal on the planet. These are the first true leaf-lobed organisms. The structure of the fern, the features of its life cycle and distribution in nature will be considered in our article.

Features of the structure of ferns

As a rule, ferns grow in the forests of the temperate climatic belt. Their body consists of a modified shoot, located under the ground - rhizomes. Above the ground, only the leaves are visible. This is the external structure of the fern. The diagram below illustrates the nature of the leaf arrangement. It clearly shows that additional axes are attached alternately to the main axis, and directly to them sheet plates.

The underground structure of the fern is also represented by a system of accessory roots, which bunch depart from the modified shoot.

But fossil forms of fern-shaped ones are not at all similar to their modern relatives. Along with the grasses, there were small bushes and giant trees, reaching a height of several tens of meters.

Life cycle

The external structure of the fern changes periodically. How is this possible? The thing is that during the life of ferns there is a process of alternation of generations: sexual (gametophyte) and asexual (sporophyte). They differ in the way they reproduce, develop, and have a number of significant morphological features.

Sporophyte

The fowl-generation fern is a green leafy plant. We used to see him in the woods. In this form, a fern (the photo below shows a sporophyte) there is a predominant part of its life cycle. On the underside of the leaves of the plant there are sporangia - the organs of asexual reproduction. They are collected in specialized structures - Soruses. In them are cells of asexual reproduction, which are called spores.

Gametophyte

Getting into the soil and germinating, spores give rise to the sex generation. Such a gametophyte also determines completely different features and structure of the fern. It has the appearance of a flat green plate, which in the course of time takes the form of a heart. To the soil, the gametophyte is attached with the help of rhizoises. These threadlike formations in appearance and performed functions resemble roots of plants, but do not form tissues. The genital fern generation is bisexual. The process of fusion of gametes is possible only in the presence of water. As a result, a zygote is formed - a fertilized egg. Developing, it gives rise to the embryo, and then to the adult plant. At first the young sporophyte is not capable of photosynthesis, so its nutrition is due to the green plate of the sex generation. As the development and the emergence of the ability to photosynthesis, the adult leaf-and-leaf plant begins to function separately.

A variety of fern-like

Currently, scientists-taxonomists have about 10 thousand species of representatives of this department. Among aquatic ferns, salvinia is the most common. This plant floats on the surface of the water and looks very similar to algae. Together with marsilia and azolla, salvinia is a group of sporadic ferns. These are typical aquatic plants.

However, in the predominant majority of cases, a fern (photo shows a perennial plant) is a forest dweller. And most of them are representatives of a group of equispores. The most common of them are common eagle, female maid, male shield, male centipede. It is about such types of fern that there is still a beautiful ancient legend. If a night on the holiday of Ivan Kupala find find in the forest this flowering plant, you can get amazing abilities. For example, understand the language of any living being. This beautiful legend has arisen because no one has ever seen the flower of a fern. Our ancestors did not know that this is simply impossible, because spore plants do not form flowers and fruits.

In the tropical forests there are several species of tree ferns. Like all higher spore plants, they prefer moisture, so they grow along streams and rivers. Very often in these places thickets of tropical ferns form a real jungle.

The importance of fern-like

It is the external structure of the fern and its features that have now made this plant one of the most popular ornamental crops. It is widely used for landscaping of various landscapes and territories. And lovers of indoor plants have long looked after various kinds of ferns for the greening of houses, apartments and various premises.

In nature, these plants are an integral part of many ecosystems, significantly increasing their biomass.

However, the greatest importance of ferns is the formation of a very important mineral - coal. In antiquity, all spore plants were giant trees. From their dead trunks under conditions of high pressure and lack of oxygen, coal was formed. Scientists-paleontologists still find in the layers of this substance the fossilized remains of ancient spore plants.

Great importance of fern-like and in medicine. For example, the rhizome rhizome has a very strong antihelminthic effect. But the adianum (venene hair) causes a vomiting reflex, while not irritating the mucous membranes. It acts as a laxative and diuretic. For a long time, the grapnel was used as an antidote for snake bites. In Tibetan medicine the centipede virgin is widely used. It is used to prepare painkillers and anti-cold medications.

The fern structure is the most complex and progressive among all higher spore plants. In its life cycle, a sporophyte predominates. Modern ferns are most often represented by herbaceous life forms, which occupy an important niche in a variety of ecosystems.