Answer:
A cactus is a plant that is able to grow in harsh conditions. These conditions include dry and desert environment. This kind of environment has high temperature and there is a need of certain adaptation which will help the plant to strive in such conditions.
The spines on a cactus plant helps the plant to get protection against animals and humans. Its root are spread upto a large surface area to grab and store water when it rains.
The spines are the structure that helps a cactus to live in desert conditions.