Ecosystem, by and large, to a small extent depends on the vital activity of vegetation of lower groups. Mostly positive influence on it is exerted by some representatives of the upper class. There are exceptions among algae. These include the department of Chara algae, which has existed since ancient times. Another thing is that today this group of species is not as widely represented as other representatives of the kingdom. By the way, algae of this category are called charophytes.
General information about the group of characeae
Externally, algae are massive branching plants that have many differences from other representatives of the kingdom. If we approach superficially the analysis of the structure of representatives of this group, then it is quite possible to confuse them with the higher classes of vegetation. This is due to the fact that the hara combine the features of lower algae and higher plants, which is also manifested in their functions. It is important to note that there are different species of this group, combined into genera. To date, the following examples of Chara algae stand out: Hara Aspera, Nitella Flexilis, Nitella Sincarpa, etc. Some species tend to live near water bodies, while others are found in sea bays,continental brackish lakes. Most often, characeae grow in arrays of several representatives, and not singly. Thus, they form thickets, covering vast areas along the bottom of the reservoir.
Plant systematics
For a long time, scientists could not determine with high accuracy which systematic group of plants the charophytes belong to in their main genera. The fact is that the presence of chlorophyll groups A and B in the cells gave grounds to classify plants as representatives of the Chlorophyta division. The presence of starch as a reserve enzyme also testified in favor of such a classification. According to other studies, the algae must have been included in the division Charophyta. The basis for such statements was the early separation of plants from green algae. There was also a point of view that the group could be considered as an intermediate link from bryophytes to green algae. Modern results of biochemical, molecular and ultrastructural analyzes define characeae as representatives of the Streptophyta division. This category also includes zignematal plants.
Basic genders
To begin with, it should be noted that there are three main genera of these plants. This is directly Khara, as well as Nitella and Tolipella. Representatives of the first genus are characterized by a cosmopolitan distribution and prefer shallow water bodies. Their natural habitat is a depth of 1-1.5 m. It is important that the water is clean and not muddy. In some aspects, this genus can be called the mostunpretentious - for example, plants can live in both brackish and freshwater conditions. However, polluted water is not good for them. As for the genus Nitella, its representatives are more prone to fresh water, and are also found in reservoirs with a sandy bottom. If Chara algae of the first genus do not like substrates, then this genus fully allows such a neighborhood - for example, with silty fragments. Tolipella is also sensitive to pollution, while it readily breeds on sandy soils and mainly in shallow depths.
Habitats
In Russia, this group of algae lives within the West Siberian Plain and Altai. Since the middle of the nineteenth century, scientists have regularly discovered new populations and places in which algae breed. It is noteworthy that under certain conditions, characeae can even have advantages over representatives of higher plants. For example, this is observed in the drying and watering areas of reservoirs. To date, 17 Chara species and 4 Nitella species have been found in the south of the West Siberian Plain. There are also less common species, which may also have competitive advantages for their development over other vegetation. At the same time, charophyceous algae are not limited to water bodies and swampy areas. Representatives of the genus Nitella, for example, are found only in the valleys of large rivers and forest steppes. And this despite the fact that, in general, the diversity of characeae in such places is noticeably lower compared to the samebodies of water.
Building
Characeae have one of the most complex structures of the thallus, which in some way determined their similarity with higher plants. Their body differentiates into internodes and full-fledged nodes, in which the whorls of branches are located. In slightly saline and fresh lakes, they are attached to the ground by means of rhizoids. As for the common features with higher vegetation, in this context we can mention the hornwort and horsetail. In height, the thallus reaches an average of 30 cm, although there are also specimens of 120 cm. Lateral branches are very limited, so the plant does not populate the bottom very densely. But this is not all the features that Chara algae have. The structure of the internode is distinguished by the presence of a long cell overgrown with a bark of other narrow and small cells. It is noteworthy that the shell of such cells is calcified.
Algae breeding
Chara group of plants is characterized by sexual and vegetative reproduction. The vegetative method is implemented using nodules located on rhizoids. In addition, star-shaped cell accumulations located on the stem lower nodules are intended for this function. It is they who give life to the new thallus. The sexual organs, represented by oogonium and antheridium, reach the highest development in the process of plant life. These are multicellular structures that often develop on a single plant. However, dioecious charophytes are also known, but their distribution is not so great. Due to its unpretentiousness to the living conditions of the hara for onlyfor several years they are able to cover huge areas, forming continuous thickets.
Reproductive Organs
Antheridium looks like a ball, the diameter of which can be 0.5 mm. Initially, it has a greenish tint, but in the process of life it changes to red or orange. It is located on a unicellular short stalk and contains 8 flat cells in the structure, closely contacting each other with notched edges. From the central part of each shield cell, a kind of cylindrical handle is directed to the antheridium, ending in a round head, on which several more cells with a smaller fraction are placed. Each of them gives rise to several hundred more cells with the help of spermatogenic filaments. In turn, each of the newly formed cells also creates an antherozoid. As for the oogonium, it has a rather large size when compared with the antheridium. Core cells encircle it with a spiral and form a kind of crown. Chara algae contain one large egg in this organ. The spermatozoon passes to the cells of the crown and is screwed into the oogonium. Further, through karyogamy, the formation of a zygote occurs.
Functions of char plants
In the biosystem, the importance of the vital activity of these algae is insignificant, although experts note some influence on the hydrological background and the biological quality of the water bodies in which they live. In particular, the water regime is becoming more stable andit also occurs the formation of a special biocenosis. Plant thalli acquire a large number of epiphytes in the process of development. These are microscopic bacteria and algae that serve as food for invertebrates. In addition, dense chara algae can act in some way as a haven for small fish, which find places of protection from predators in the thickets. In reservoirs with a dense development of such vegetation, more small mosquito larvae are observed. This is due not only to providing protection, but also to the action of special antibiotics that plants secrete. At the same time, algae can become food for birds. This is observed during periods of autumn passages over water bodies. Waterfowl predominantly use zygotic oospores, which at this time are filled with fat droplets.
Application in the economy and science
The nature of the use of plants in human life is determined by the substances contained in it. For example, the presence of lime makes algae attractive for use as a fertilizer. In particular, the Charophyta division is useful in terms of nutrition of heavy soil layers. And even without additional processing, natural accumulations with char deposits form therapeutic mud. In recent years, interest in this group of plants has been shown by specialists in the field of biophysical research. Large cells that form internodes provide an opportunity for a deeper study of cytoplasmic membranes for their permeability.
Conclusion
Characeae are gradually losing their positions in the plant hierarchy. Despite the resistance of some types of these algae to external influences, the spread of pollution in hydrological resources still inhibits the processes of their development. Also, do not forget that Chara algae is a group of lower algae, which is a transitional link between different departments. And although scientists today confidently systematize this group, many signs of its representatives indicate evolutionary changes in the same thallus. On the other hand, experts admit that, compared with the oldest fossils, modern chars do not differ in such a rich diversity.
