Forest trees and their root fungi share resources and information. The plant makes and delivers food to the fungus; the fungus increases the plant’s water and mineral absorptive powers. Trees of different species can communicate with and support one another via their mycorrhizae. 

It is known, that plants can communicate with unrelated species through the air. Plants getting chomped by herbivores, eaten by insects or attacked by pathogens release volatile chemicals that are sensed by neighboring plants, who up their defenses pro-actively.