Everyone who at least touched on botany issues had heard of such a distinction between plants as flowering and non-flowering. At the same time, the latter also have another name, reflecting the essence of their method of reproduction - spore. What plants are called spore plants? Those who have chosen the most ancient evolutionary method for the propagation and distribution of their seeds - the formation of tiny, diverse in form structures - spores.
What plants are called spore plants?
To answer this question as fully as possible, we begin by defining the dispute itself (translated from Greek spora - "seed", "seed" , "sowing"). This is a small structure with a size of not more than 1 ΞΌm (10 -3 mm), diverse in shape and color, which plays the role of a seed in all spores, giving rise to the development of the embryo of the future plant.
Forming spores is not the prerogative of all types of plants existing today. It is believed that such an ability generally came to representatives of the flora from the distant past, when the first land plants were just beginning to appear, and life besides water was born on land.
It is known that the most ancient plants are algae, horsetail, crowns and ferns. Their historical roots go back to such periods as Cretaceous, Carboniferous and Silurian. And they are still the inhabitants of forests, plains, marshes, steppes and the polar edge of different continents.
Such a long existence has become possible for them, partly because they are just related to disputes. Therefore, the question of which plants are called spore plants, we can give a very definite answer. These are ferns, mosses, crowns, horsetails (from the higher category), as well as algae and lichens from the lower category.
Distinctive features
The main features that distinguish all spore plants include the following:
- Due to the formation of structures such as spores, these plants never form flowers (they are not biologically adapted to this). Therefore, all the myths about blooming ferns on the night of Ivan Kupala are just fairy tales.
- The life cycle of these plants has its own characteristics. Spore plants are distinguished by the alternation of generations in the life cycle. Thus, gametophyte, the sexual generation formed by the fusion of sperm (anteridia) and ovum (archegonia), forms an adult plant producing spores over time. A sporophyte sprouts from a spore - an asexual generation that forms small spores in special structures and gives rise to a new plant. Such a change in the sexual and asexual generation accompanies spore plants throughout the entire period of their existence.
- For breeding, they definitely need water. It is through the fluid that the sperm gets to the archegonia, in which the egg is hidden. Without water, the process of fertilization in spores is impossible. This is another proof that these are the most ancient representatives of the flora, whose life has always been closely associated with the aquatic environment. It is from there that all plants originate.
These are the main features that distinguish spore plants from seed plants. Now let us consider in more detail the main representatives of this department.
Ferns
Ferns are the most widely known spore plants both for decorative purposes and historically established notions of the ancient flora. Examples of plants are known to all amateur gardeners and lovers of nature and forest solitude. Orlyak, a wanderer, an ostrich are chic plants by volume, attracting with the splendor and richness of green foliage. They are ubiquitous in forest areas in areas with a temperate climate and high humidity.
Those who love homemade potted flowers probably also have or have seen nephrolepis in others - the most common indoor fern. In addition to external beauty, such plants are quite unpretentious and require only plentiful and constant watering. Like all spores, they are not able to reproduce without water.
On the leaves of ferns, sporangia with spores are very clearly visible. They are located on the back of the waya (leaf) and have the appearance of small rounded bags of brown or dark orange color. Spores are densely strewn with fine yellow powder in them. After maturation, sporangia opens, and spores spill out into the environment.
In total, ferns account for more than 10 thousand species, united in 300 genera.
Mosses
Very interesting and beautiful plants that form a real forest litter, similar to a carpet - mosses. Spore plants that have very small structures - a stem, leaves, a stem with a sporangium in the form of a box - are all about them. Therefore, few people distinguish them in appearance, unless true experts on mosses.
The color of these plants is saturated, juicy green, leaves are hard, small, wedge-shaped. Although there is another form, it depends on the type of moss. The main groups at the moment are as follows:
- polytrich;
- shave;
- hypnous;
- sphagnum.
In total, there are about one hundred species of mosses, so the list below includes only the most common and of practical importance.
An interesting feature of these plants is that their sporangia are similar to circles with caps of various shapes. When the spores mature, the lid opens, and the stem, on top of which the sporangium is located, bends, and the spores spill out.
Seaweed
Algae are spore plants, numbering today about a hundred species, combined in 11 main departments. The main distinguishing feature of these representatives of the flora is life in the aquatic environment at various depths. Their body is represented by a thallus; it has no leaves and roots. The function of the latter in these plants is performed by translucent tenacious hooks, called rhizoids.
Algae belong to lower plants precisely because of the lack of division of the body into organs. They also reproduce by spores. The main four departments of algae, which are the most widespread and applicable in human practice, are as follows:
- Greens.
- Brown.
- Reds.
- Diatoms.
Horsetail
Together with ferns, this group of spore plants once populated all the land, but gradually went to the formation of deposits of peat and coal. Today, horsetails are represented by a small number of species - there are about thirty of them.
The most common in Russia is horsetail. It has the appearance of a low plant with a rigid erect stem, divided into small segments by internodes, from which come out bundles of leaves that look like needles. Therefore, in general, horsetail resembles a small Christmas tree.
Dividing the body into small segments is a distinctive feature of all these representatives of the flora. Horsetail propagates, like other spore plants, by means of generational change, that is, asexually (by spores) and sexually (by sperm and ova).
The ploon
An interesting group of marsh plants, which differ from all other spore plants in their appearance. They have beautiful stems dotted with small leaves. Each of them seems to creep on the ground.
In total, there are about forty-five species of mocks. Plant biology is no different from that of the previously discussed spore plants. They also have a sporophyte and gametophyte change in the life cycle , they depend on water, therefore they grow only on marshy and very moist soils. Their sporangia are small dense elongated structures. After maturation of the spores, they burst, and the spores go outside.
Lichens
About 26 thousand species of these plants, combined in 400 genera, totals modern biology. These plants have distinct from all other features of the structure and lifestyle. The fact is that they are a product of close mutually beneficial cooperation, a partnership between two types of living creatures - unicellular algae and fungi.
Such a symbiosis has several advantages:
- tolerance to temperature fluctuations (lichens are able to survive in the conditions of the extreme Arctic);
- constant exchange of nutrients (algae gives organic to the fungus, and the fungus gives it minerals);
- adaptability to various soils.
Therefore, lichens are although lower spore plants, but they have undoubted advantages over higher in terms of lifestyle.
Phylogenesis
It is from spore plants that the modern flora of our planet began to exist. According to a number of theories, life originated in the ocean. The first plants, which were the lower spores, algae arose there. Gradually, they moved to land, they formed leaves and roots for keeping in the soil. However, water was still needed for breeding.
Then, algae gave rise to ancient ferns, horsetails, mosses and mocks, which, during the process of dying for several million years, formed entire mineral deposits. If the ancestral forms of spore plants had a woody structure, then modern ones have nothing to do with trees.
The entire process of phylogenesis of the described representatives of the flora took about four hundred million years. However, now the general characteristic of spore plants allows them to be distinguished as a super department, which has not yet lost its final connection with its ancestors (water still needs to be propagated), but it has already formed and has new features.
Home Applications
Characterization of spore plants allows us to understand that they are not of such global practical importance as flowering ones. However, the scope of their use is numerous:
- The woody forms of spore plants in the middle of the Selur and the Carboniferous period formed the huge deposits of coal that people still use.
- Young shoots of ferns can be eaten.
- Different parts of horsetail and fern plants are used in medicine as painkillers, diuretics, astringents, anti-inflammatory and other drugs.
- Plaunas have very small and soft texture spores that can be used as baby powder.
Thus, we received a complete and detailed answer to the question of which plants are called spore plants.