When plants are under stress, they cry for help.
They release chemicals in patterns, and physicists have developed a device that can actually 'listen' these stress responses! Why do plants do this? One theory is the chemicals serve as a kind of natural insect repellent. Another is that they attract even bigger insects, which then feed on the invading pests. Or the chemicals are a way for plants to warn their neighbors of impending attack.
The conclusion: plants can communicate with the environment. It's just a matter of us learning the language.