How did so many plants form? To understand this problem, we must first understand the simple history of plant development on the earth and the process of plant species formation.
About 3 billion years ago, plants appeared on the earth. Primitive plants are extremely simple in structure and poor in species, and all live in water; Hundreds of millions of years later, some plants moved from water to land. The environmental conditions on land are different from those in water, and the living conditions are varied and varied. What climate change, what orogeny, what glacier movement, what volcanic eruption, what seawater intrusion and so on. , really changing. In this way, the original shape and structure of plants can not meet the needs of land life without transformation. For example, when plants live in water, they use the whole surface of their bodies to absorb nutrients. On land, they need special organs to absorb water and minerals from the soil on the one hand, and carbon dioxide and oxygen from the atmosphere on the other.
Therefore, many characteristics acquired by plants in the process of adapting to water life will change significantly and become complicated when adapting to land life. The development of plants to land is accompanied by the emergence of roots, stems and leaves that adapt to the structure, and finally flowers, fruits and seeds appear.
The further development of the plant kingdom is along the road of adapting to this new and more complicated living environment.