Plants do not feel pain the same way animals do because they lack brains and nervous systems. However, there is evidence that plants react to damage by emitting chemicals or gases that communicate discomfort or stress and that they somehow adapt to minimize this discomfort.
Although some scientists argue against the concept of plant neurobiology because it is anthropomorphism, as plants do not have neurons, others consider it to be a useful metaphor of plant adaptability. Instead of brains, plants use a complex network of sensitive cells to gather data from their environments and react to it. By emitting a scent when they are cut or eaten, they communicate with nearby plants, which are able to react to the danger by producing defensive chemicals. A recent study showed that plants are also able to communicate the pain or stress of drought from root to root.
A study in Germany used a laser microphone to detect the stress level in plants. The gases that the plants emitted when they reacted to various stimuli were picked up by the microphone as sounds. According to the researchers, the stress levels plants exhibited when parts were cut off translated as the plants crying out in pain. The scientists use this information to devise ways to monitor the condition of plants so they can be shipped from place to place without rotting. Farmers can also theoretically use plant sound monitors to detect early pest infestation.