It is customary to distinguish four periods in plant life.
The first period begins with the formation of a zygote and lasts until the germination of the seed. At this time, the formation of the embryo occurs as a result of multiple division of the zygote. Therefore, it is called embryonic.
The second period, the vegetative period, or the period of youth, begins with the germination of the seed and continues until the first flowering.
In the beginning, the plant is a seedling. His nutrition depends on the reserve nutrients accumulated by the mother’s body. As the shoot and root systems are formed, the plant moves completely to independent life.
The third period, the generative period, or the period of maturity, begins with the appearance of generative organs (flowers, fruits and seeds).
In the fourth, final period of life – the period of old age – the shoots and roots of the plant grow very slowly, it loses its ability to form generative organs.
Since the total life span of plants is different, the duration of these periods is not the same for different plants.
Annual plants go through all periods in one year.
Biennial plants in the first year are in the vegetative period, and in the second year they pass into the generative period.
Perennial plants have the longest generative period, when they form a large number of seeds, ensuring the spread of their species.