Do plants and trees communicate?

There is a form of chemical communication that goes on. There was some research done recently where they looked at plants having their leaves pulled off, and they found that the plants scream chemicals to signal that this damage has occurred. There are a number of chemicals produced. One of them is called ethylene (H2C=CH2) and that is a signal that tells the plant that it is being damaged to grow some more. It also makes fruit ripen. Bananas produce lots of it and so can help other fruit to ripen much faster. There is also communication between plants and the fungi in the soil (a mycorrhizal relationship). Fungus is very good at extracting water and minerals from the soil, and it swaps these with a plant, which will provide it with sugars to give it energy, so both benefit. People used to think that there were two species of thistle, a dwarf and a tall thistle, but they were both the same species, just with different fungi, referred to as Hartig nets, growing around their roots.