Lignins form a group of phenolic macromolecules composed of different monomer components. These are solid biopolymers that are incorporated into the plant cell wall and thus cause cell lignification. About 20 to 30 percent of the dry matter of woody plants consists of lignin. This makes lignin, along with cellulose and chitin, the most abundant organic compound in the world. The evolution of land-based plants and, in particular, trees is very closely linked with the formation of lignin, as it is essential for the rigidity of plant tissue. Only lignin enables plants to form strengthening elements that ensure the stability of larger plant structures outside of water.