Answer
Lignin allows for the strengthening of plant cell walls and, thus, of organs and entire plants. This allows for support to be given to larger and heavier plants. This translates into the evolution of larger and thicker leaves and much taller plants, ultimately resulting in the evolution of trees. In order to produce stable, stronger, thicker bodies, this further required the evolution of secondary growth and with the growth rings that it produces, leading to thick, strong plant bodies in woody plants. It also allowed for better transport cells, making plants able to live in drier and drier habitats.
Work Step by Step
Lignin allowed plants to reach up from the boggy ground in which they first came onto land and to stretch up into the sky and out into deserts.
