Here's why:
* Cold-blooded (also called ectothermic) animals rely on external sources of heat to regulate their body temperature. They get warmer in the sun and colder in the shade.
* Warm-blooded (also called endothermic) animals regulate their own internal body temperature, usually keeping it constant regardless of the environment.
Plants do not have the same internal temperature regulation systems that animals do. They are poikilothermic, meaning their internal temperature fluctuates with the environment.
While plants can generate a small amount of heat through metabolic processes, they do not have the ability to maintain a stable internal temperature like warm-blooded animals.