When plants moved on the land they had to adapt to new environment and to deal with new problems. The main problem for plants was to figure out how to regulate water loss within the cells. One of the solution was the formation of the waxy covering on top of leaves-cuticle, which evolved on the surface of leaves to reduce water loss. Another problem for plants was to figure out how to obtain resources from soil and air, so they developed vascular tissue to transport water/sugar within the plant.
