Why did plants need to evolve adaptations for hot arid climates?

Plants in hot deserts have to adapt in order to live. Here are some possible adaptations: Some have tiny thorns of their exterior, to prevent predators from eating it. Large stems, may store large amounts of water, as water may be hard to come by. Wide spreading/long roots, alowing plants to gather water found in the ground. Coated leaves, prevent water from escaping the plants, and from burning. Plants must adapt to the hot climate and conditions in order for the plant to live. the hot sun could easily burn and kill the plant and therefore the plant must protect itself. :)