Question

Tropics mostly have evergreen plants. Give reason.

Answer 1

At the tropic, weather pretty much remain the same. As well as the condition are favorable for their growth. So plants do not have to face the extreme of changes. Which makes the environment more stable and very healthy for plants. Thus they are ever green. 

Answer 2

The reason behind is that the tropical regions have more rainfall and sunshine. The weather there is mostly constant and does not change much. And another reason for this is that the trees there do not shed much leaves which is why they are known as evergreen plants.