What is a thallus? Morphology and function of the thallus

If we consider the body of a higher seed plant and any kind of algae, one can notice a great difference in structure and morphology. And this is not surprising, because the evolution has developed so that modern flowering plants are much higher organized than real algae. The main difference is in the structure of the body, which in algae and some other organisms is represented as a thallus.

What is a thallus?

The shape of most modern algae is very diverse, thanks to the simple structure of the body, which in the course of evolution has changed and transformed, depending on the environment and other important natural factors. The body of the body, which is not divided into separate, functionally independent organs and consists of poorly specialized tissues, is a thallus. This definition is suitable not only for algae, but for a lot of mosses, as well as all lichens and some fungi.

The thallus is an important sign of the simplest development of plants and other organisms. It performs all functions at once, which belong to the leaves, root or stem separately for a more perfect organization.

So what is a thallus? This is the main functional part of the body, which is responsible for growth and reproduction. The simplicity of the organization of this structure to some extent made it possible to master those habitats where modern plant species could not grow. The presence of thallus can be called a kind of plus.

Differences of thallus from the body of higher plants

There are several fundamental differences in the anatomy and morphology of the body between the current spore, seed plants and such low-developed organisms as algae, mosses, lichens.

1. The thallus is not divided into vegetative and generative organs, but is a continuous amorphous body that can take a different form.
2. In the thallus of algae, mosses and lichens there is no any differentiation on the tissues. In very rare cases, the outlines of individual groups of cells that perform similar functions are visible.

Forms of thalli in different organisms

The thallus of algae is also called a thallus. It can be filamentous, lamellar, sifonal, bushy, roundish, ribbon-shaped, arrow-shaped. The shape of the thallus of these organisms is quite diverse not only in shape, but also in color: the body of the algae can be green, brown, red, yellow or yellow-green, brown.

Lichens also have different forms of their thallus. They may be:

1. Scale: Thall tightly fuses with the substrate on which it grows, and then the body of the lichen can not be torn off without damaging the structure of this substrate.
2. Leafy. Their difference lies in the small number of blades leaving from one point, which easily detach from the substrate.
3. The bushy. They can reach large sizes in length, often are well and densely branched.

Among the fungi there are also thalloma forms, but in this kingdom the presence of groups of organisms for which thallus is characteristic is, rather, an exception than a rule. For them, the formation of the body is a mycelium.

Is it appropriate to use the term "thallus" everywhere?

Not all mosses have a thallus. For representatives of the orders, hepatic and sphagnum mosses are almost without exception. Green mosses, which include, for example, Kukushkin flax, are still divided into departments. However, they are not true stems and leaves, so they should be properly named Cahulidium and Phyllidia, respectively. Nevertheless, despite the simplicity of the organization of such a body, its thallus can not be called.

What is a thallus in biology, we know and often in the example of algae as a lower plant. However, even here there are exceptions, since not all representatives of these organisms are multicellular. On the contrary, many of them are unicellular or colonial structures, which it will be mistaken to call thallus.

Conclusion

We examined what a thallus is, what it can be represented and what forms it takes. Despite the simplicity of the organization of algae, mosses or lichens, it is worth noting the importance of the presence of thallus in the structure of their body. Due to this distinctive feature, they were able to master such habitats where it is difficult to master many modern highly developed plants.

Tallom performs all the functions that are inherent in the usual organs of flowering plants. It easily absorbs water throughout the body, photosynthesizes, thanks to the presence of a special pigment. And, by the way, the variety of the color of algae is the result of the work of different photosensitive pigments that allow these organisms to dwell at different depths without interfering with each other during the absorption of light. That's what the thallus of algae is.