Adaptation of terrestrial plantsThe plants we know today as terrestrial organisms were not always terrestrial. Today's land plants may be related to aquatic organisms that existed millions of years ago. In fact, early fossil evidence shows that the first land plants may have appeared around 450 million years ago (Weng & Chappie 2010). Plants that once resided exclusively in water were able to adapt so that they could settle on land. It is assumed that the need for plants to move on dry land was created by the drying out of water, causing plants to have less space and causing them to move towards land. Although the exact cause of plants' need to move to a terrestrial environment is unclear, it is known that plants had to undergo several adaptations to be able to live on land. These adaptations include: lignin, cellulose, suberin, and changes to the plant surface, including the formation of a waxy cuticle. Lignin is one of the key elements that allowed plants to evolve to a point where they could survive on land. Lignin is a macromolecule that serves to bind cellulose and create strong structural support for plants. A plant's ability to grow is particularly limited by its strength, making lignin crucial for vascular plants. Plants lacking lignin are often nonvascular and are less evolved than lignin-containing plants. Without lignin, land plants would not be able to stand upright, which would interfere with many elements necessary for their growth, such as the conduction of sunlight and avoidance of shade, or the ability to grow outside. areas without light. Besides the obvious strengthening of lignin for this purpose, it can also help plants in other ways. For example, lignin contains a specialized water pipe...... middle of paper ......ulose will be protected from anything that could potentially damage the cell otherwise. It also plays a role in helping cells maintain their shape. Cell walls, along with cellulose, provide support for plants so they can grow while maintaining their shape. The size of the plant will determine how much cellulose it will need, but all plants need it and use it constantly. Plants have also had to adapt above ground to survive climate change linked to their migration to dry land. Changes to the plant surface are best observed by the formation of cuticular wax. This waxy cuticle is waterproof and acts as a method of controlling the plant's water consumption. It can be made thinner or thicker depending on the needs of the plant and the environment at the time, changing in response to droughts or excessive rains..