Juicy tomato, aromatic pear, dry acorn and exotic carambola - all this can be called one phrase - “angiosperms fruit”. It is formed from a flower and is widely used by a person in his life. How is the formation of this organ of plants, we will consider in detail in our article.
What plants belong to the angiosperms
Angiosperms currently dominate the planet. The department of this plant kingdom has over 250 thousand species. They reached this level of distribution thanks to the progressive features of their structure. They are characterized by the presence of a generative reproductive organ - a flower, double fertilization. Such plants reproduce not only vegetatively, but also with the help of seeds. The angiosperm fruit is formed from a flower.
Features of double fertilization in flowering plants
The main functional parts of the flower are the stamen, in which male germ cells develop, and the pestle. In this part, there is a female gamete and a central germ cell. The process of fertilization in flowering plants is preceded by pollination. It consists in transferring pollen from the anther of the stamen to the stigma of the pestle. This process occurs with the help of wind, water, insects or humans.
The angiosperm fruit is formed from the lower expanded part of the pestle, which is called the ovary. Two sperm are involved in the fertilization process. Once on the stigma of the pestle, they cannot independently move into the ovary of the pestle. This happens with the germ tube. It gradually grows down - from the stigma through the column into the ovary. And with it, a pair of male gametes descends. This flower structure can be compared to the elevator of a multi-storey building.
Having reached the ovary, one sperm combines with the egg, forming the germ of the seed. It contains all parts of the future plant. This is the germinal root, stalk, leaflet and kidney. And the second sperm merges with the central germ cell. As a result of their connection, an endosperm is formed, which serves as a reserve nutrient. Over time, a seed forms inside the fruit. It consists of an embryo, an endosperm layer and a peel. Seed is a generative organ of flowering plants.
Angiosperm fruit
One of the progressive features of flowering plants is that their seeds are well protected. Since the fruit of the angiosperms is formed from the ovary of the pestle, its walls protect the seed developing inside from all adverse environmental conditions. This generative organ of plants consists of seeds and pericarp, which, in turn, is formed by three layers: external, middle and internal. Depending on the structure, dry and juicy fruits are distinguished. For example, drupes of cherries and plums have an outer membranous, fleshy middle and ossified inner layers.
What is the fruit formed in angiosperms
In the vast majority of cases, the fruit in angiosperms develops from the walls of the ovary of the pestle. In this case, it is called real. Examples of such structures are drupe, berry, bean, capsule, achene. If additional parts of the flower take part in the formation of the fruit, it is false. It can be an overgrown receptacle, a calyx. False is a juicy polyspermous apple fruit, which is characteristic not only of the eponymous representative of the Rosaceae family, but also of quince, mountain ash, rose hip, hawthorn, and irgi. Everyone knows black and red currants, elderberries, gooseberries, viburnum, cornel, have a similar structure.
The structure and classification of fruits
Since the fruit in angiosperms develops from parts of the flower, their structure is interconnected. This is easy to prove. For example, if there is one pestle in a flower, as many simple fruits are formed from it. In the case when numerous ovaries grow together, a complex generative organ is formed. This happens with raspberries. This fruit is the result of the fusion of a large number of drupes. And with strawberries and strawberries, small nuts are immersed in a juicy and fleshy base of the receptacle.
Fruits are grouped in several ways. First of all, this is the number of seeds. In the second - structural features of the pericarp. According to the first sign distinguish single- (drupe, achene) and multi-seeded fruits (berry, capsule). By the second criterion - juicy (orange, pumpkin) and dry (bean, nut).
The value of fruits in nature
Fruits are of great importance for the distribution of seeds and the spread of plants. Having a juicy and tasty protective shell, they are a favorite treat for many animals. Eating fruits, herbivores simultaneously distribute seeds, moving from place to place. The layers of the pericarp are reliable protection of seeds from changes in environmental conditions, temperature fluctuations, lack of moisture and heat. Since ancient times, man has been using fruits for food, artificially breeding many types of fruit, berry, melon and fodder crops. Every year, breeders create new plant species with high yields.
So, the angiosperms fetus is formed from the walls of the ovary of the pestle, as well as other parts of the flower: the receptacle or carpels. In any case, the fetus is the result of flower development, double fertilization and performs the function of plant propagation.