If you think it's weird that plants can "talk" to one another, here's something even weirder: one way they talk to one another is via a network of underground fungus!
Many plants have a chemical armoury that they deploy when aphids attack, with chemicals that both repel the aphids and attract parasitic wasps that are aphids' natural predators.
The team grew sets of five broad bean plants, allowing three in each group to develop mycorrhizal networks, and preventing the networks' growth in the other two.
To prevent any through-the-air chemical communication, the plants were covered with bags.
As the researchers allowed single plants in the sets to be infested with aphids, they found that if the infested plant was connected to another by the mycorrhizae, the un-infested plant began to mount its chemical defence.
Those unconnected by the networks appeared not to receive the signal of attack, and showed no chemical response.
Link (Image: Microbe Wiki)