Flowering plants

The vegetative world of the 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 the water and up to huge trees reaching a height of more than 90 meters. In this case, shrubs and trees have a wooden stalk, and the grasses have a thin juicy stem.

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 fragrance, and can be like grass, be small and unattractive.

Any flower consists of several parts, each of which performs a certain function. Sepals - the outer part, protecting this organ at the kidney stage. The most visible 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 stamens. Pollen from a plant to a plant is transferred either by the wind or by insects. Ovary - receptacle for female sex cells. Fertilization in flowering plants can occur only when the pollen grain is combined with the ovary. Often these plants have 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 process of photosynthesis occurring in leaves is the conversion of carbon dioxide and water under the influence of solar energy into nutrients. The leaf feeds flowering plants. By the stems, which are the support of the whole organism, both through pipes, water comes from the root to the leaf. The roots carry out their unique function: they keep the complex construction of the plant due to the rod that extends deep into the roots, and the smaller rootlets spread at the very surface of the soil, and also extract water and mineral salts from the depths of the earth.

Fertilization of flowering plants occurs in the following way: the egg cellulose and pollen combine, and seeds form in the ovary. Before this, the process of pollination takes place. Pollen is transferred from flower to flower either by wind, or by bees, butterflies and other insects. A delicate aroma and a bright color of the flower attract pollinators. For them, at the base of the petals, sweet nectar accumulates. In the process of searching for this sweet product, pollen grains stick to the abdomen, paws, wings of the insect, and since these sweets are not limited to visiting one flower, the pollen easily falls on others. Flowering plants produce a huge amount of pollen, which is carried by the wind, and the stigmas of flowers catch it as in a network.

As soon as the pollen grains come from the flower to the flower, small tubes grow into them, which, reaching to the ovary, connect the male sex cells with the 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 capsules).

As for the life cycle, the flowering plants can be annual, biennial and perennial. With the 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 expelling the shoots, which at first bloom, bear fruit, and only then will die. Perennial plants bloom for many years, pleasing us with beautiful flowers.