In our article we will consider biological concepts that relate to the vital activity of higher plants. These are gametophytes and sporophytes, which are components of the life cycle of these amazing organisms.
Features of higher spore plants
Higher spore plants are the first terrestrial organisms of this kingdom of nature. The first natives on dry land, which are called riniophytes, had a creeping, forked-branching stem. Some fossils of this systematic unit had gigantic dimensions, reaching a height of several meters. Mastering the ground-air environment of these plants allowed a number of progressive signs that appeared in their evolution. First of all, it is mechanical and conductive tissue. Due to this, new features of life activity became possible. This is the vertical position of their body in space and carrying nutrients through the body. Among modern plants representatives of this systematic unit are 4 departments. This mokho-, plauno-, horsetail-and ferns. Gametophyte and sporophyte are two generations of the same plant, which alternate sequentially in the course of their life cycle. This process ensures the continuity of the species.
Features of the sporophyte
Sporophyte is asexual generation of spore plants. Consider its structure on the example of bryophytes. In the summer, small boxes on the elongated legs appear on the green shoots of this plant. Inside them are spores - cells of asexual reproduction. Once in the soil, they give rise to green shoots that are already multiplying with the help of gametes. Sporophyte prevails in spore moss, horsetails and ferns, as well as in all seed plants. Gametophyte is dominant only in all representatives of bryophytes, which has the appearance of a green leafy stalk.
Asexual reproduction cells develop in specialized organs called sporangia. In mosses it is a box on the leg, in ferns - sori, located on the underside of their leaves. And horsetails and moss form pineal formations on the tops of spring shoots, called sori.
Horsetail sporophyte is represented by two species of shoots. In spring, a spore-bearing stem of brown color appears. There is no chlorophyll in its cells. It develops to spore germination, after which it dies. A green summer sprout grows from the buds located on the rhizome. It is chlorophyll-carrying. This structure is clearly separated by internodes with reduced leaves. The gametophyte of this plant is almost invisible. This plate is only 1 cm in size. Some of them develop female gametes, on the other - male ones. Therefore, the sexual generation of horsetails is dioecious.
Morales are also characterized by the predominance of the sporophyte in the life cycle. These are herbaceous plants with whole leaves. They are growing all around, so the people have earned the name “witch rings”. Perennial shoots creep along the ground and have lifted stems. Their spores, collected in the strobila, are in the ground for several years, after which they germinate.
What is gametophyte
Gametophyte and sporophyte are generations successively replacing each other. When spores germinate, they give rise to the sexual generation. It is called a gametophyte. In mosses, both generations are anatomically connected, while in other spore ones they develop separately. For example, in ferns, the gametophyte has the form of a flat plate on which a bunch of adventitious roots develops. As a result of its development, the gametophyte of ferns, which is also called outgrowth, gives rise to an asexual generation.
Life cycle concept
Sporophyte plants gives rise to the sexual generation. On the gametophyte, sex cells are formed, for the merging of which a necessary condition is the presence of water. Therefore, all spore ones live on well-moistened areas of land. Gametes, unlike spores, have a single set of chromosomes. It is restored as a result of fertilization, therefore the gametophyte itself is always diploid.
So, a sporophyte is a generation of plants with the help of which asexual reproduction is carried out. During the life cycle, it is replaced by the sexual generation - the gametophyte.