After they first went ashore during the Silurian epoch, plants have developed the anti-gravitational system to survive under terrestrial environment with the strong gravitational force. The cell wall acts as a principal component of the anti-gravitational system in plants, probably with the aid of links to the plasma membrane and the cytoskeleton. The cell wall has well developed in land plants and often represents more than 90% of the dry weight of the plant. The development of the cell wall has greatly influenced the interaction between plants and other organisms, such as feeding, sheltering, invasion, and symbiosis, and has been involved in the regulation of the global environment throughout the evolution.