Why is the process of historical change called plant evolution?

During the evolution of plants, various changes took place in the structure of plant organisms. This took a long time period. In the course of these changes, new adaptations to the environment appeared. Plants came out of the water. They have acquired some organs for life on land. Over time, flowering plants appeared. There were a huge number of such changes. In the course of natural selection, only a small part of the ancient flora has survived to our time in the form in which it was millions of years ago.