The plant world of planet Earth is rich and diverse. But there is one absolutely unique group - flowering plants. It includes two hundred and fifty thousand species that grow on our planet, from the smallest duckweed living in water to huge trees reaching a height of more than 90 meters. At the same time, shrubs and trees have a woody stem, and the grasses have a thin juicy stem.
The organs of flowering plants are divided into organs of nutrition and reproduction. Through the roots, stems and leaves, the plant receives nutrition. And flowers and fruits carry out a very important function - the function of reproduction.
A distinctive feature of this group of plants is the presence of a special organ of reproduction - a flower. It can be bright and stunningly beautiful, can have a delicate delicate aroma, and can be like grass, be small and nondescript.
Any flower consists of several parts, each of which performs a specific function. Sepals are the external part that protects this organ even at the stage of the kidney. The most noticeable part of the flower is the petals, their bright color and aroma attract many insects. Pollen grains serve as a receptacle for male germ cells and are attached to the stamens. Either wind or insects carry pollen from plant to plant. The ovary is a receptacle for female germ cells. Fertilization in flowering plants can only occur when pollen grains are combined with the ovary. Often these plants possess both ovaries and stamens in one flower. Separately male and separately female flowers are found in nature in such flowering plants as oak or willow.
The photosynthesis process occurring in the leaves is the conversion of carbon dioxide and water under the influence of solar energy into nutrients. They nourish flowering plants. Through the stems, which are the support of the whole organism, like through pipes, water flows from the root to the leaf. Roots fulfill their unique function: they hold the plant’s complex structure thanks to a rod extending deep into the roots and smaller roots spread around the surface of the soil, and they also extract water and mineral salts from the depths of the earth.
Fertilization of flowering plants occurs as follows: the egg and pollen combine, and seeds form in the ovary. Before this, the pollination process takes place. Pollen is transferred from flower to flower either by the wind, or by bees, butterflies and other insects. The delicate aroma and bright color of the flower attract pollinators. For them, sweet nectar accumulates at the base of the petals. In the process of searching for this sweet product, pollen grains stick to the abdomen, paws, and wings of an insect, and since these sweeteners are not limited to visiting one flower, pollen easily falls onto others. Flowering plants produce a huge amount of pollen, which is carried by the wind, and the stigmas of flowers trap it like a net.
As soon as pollen grains fall from flower to flower, small tubules grow in them, which, reaching the ovary, connect male reproductive cells with female ones. So the eggs are fertilized, from which the seeds are formed. And at this time, the ovary grows, forming fruits (berries, nuts, dry boxes).
As for the life cycle, flowering plants can be annual, biennial and perennial. With annuals, everything is simple: they bloom only once and die, it all happens within one year. An interesting picture opens when observing biennials. In the first year of their life, there is an active development of stems and leaves, as well as the accumulation of nutrients by the roots. And only in the second year, the root uses the reserves of nutrients for distillation of shoots, which first bloom, bear fruit, and only then die. Perennial plants bloom for many years in a row, delighting us with beautiful flowers.