For the first time, scientists at Exeter University have captured on film the process by which plants alert each other to possible dangers. When a plant is under attack it releases a gas which warns neighbouring plants to protect themselves.The ability of plants to communicate with one another isn't new; the novelty is that this has now been "captured on film." It's doesn't seem likely that the flashes shown on the video are "real" - perhaps they are CGI representations of more subtle changes. The flashes (beginning at 1:30) are said to be evidence of "biological activity." One suggestion at the Reddit thread: "my guess is that these are transgenic plants containing a foreign gene known as a "reporter" that produces a visual signal of some kind in response to the gas they are interested in. This signal could be light, but it is probably very, very dim."
And I wonder what gas the plants are releasing that serves as the messenger?
(I can't embed the video; those interested will need to view it at the link.)
And a hat tip to 127001y in the Reddit thread for suggesting the phrase I used for the title.