Plants really do communicate with each other
Just not slowly and inefficiently with sound waves and "meaning" and all. Discovery:
[T]he science of plant communication is now staging a comeback. Rigorous, carefully controlled experiments are overcoming those early criticisms with repeated testing in labs, forests and fields. It’s now well established that when bugs chew leaves, plants respond by releasing volatile organic compounds into the air. By Karban’s last count, 40 out of 48 studies of plant communication confirm that other plants detect these airborne signals and ramp up their production of chemical weapons or other defense mechanisms in response. “The evidence that plants release volatiles when damaged by herbivores is as sure as something in science can be,” said Martin Heil, an ecologist at the Mexican research institute Cinvestav Irapuato. “The evidence that plants can somehow perceive these volatiles and respond with a defense response is also very good.”
Scientists are also exploring how the messages from these signals might spread. Just a few months ago, the plant signaling pioneer Ted Farmer of the University of Lausanne discovered an almost entirely unrecognized way that plants transmit information — with electrical pulses and a system of voltage-based signaling that is eerily reminiscent of the animal nervous system. “It’s pretty spectacular what plants do,” said Farmer. “The more I work on them, the more I’m amazed.”
We humans imagine the systems we build are complex; our computers, our cities. They are not. There are layers and layers of communications systems all around us: In the air, in the soil, probably even in the water. But we don't even see their presence.