They don't have eyes. Or ears. Or what we would call a nervous system. But plants can talk. And they listen. Let me show you how.
First, we'll need a plant eater. This one's perfect: It's an aphid, a hungry little critter who loves to munch on fresh, green leaves ...
Next, we arrange lunch. We choose a bunch of young, healthy bean plants with lots of broad, green leaves ...
Then we carefully drop our aphid (make that many aphids) onto the bean plants, where they land and begin to chew.