How do plants talk to each other?

grown in close proximity to sagebrush plants whose leaves had been damaged by cutting. This change appeared to be in response to chemicals – known as volatile organic compounds or VOCs – released by the sagebrush plants. Other researchers soon reported similar VOC-induced defense responses in several other plants, including lima bean, broad bean, barley, and corn. And in 2006, Karban showed that VOCs released by damaged sagebrush induce herbivore resistance in plants growing at distances of up to 60 cm, well within the range of sagebrush neighbors in nature. C But the question still remains: ‘Why should a plant waste valuable resources on a function which has no obvious advantage for it?’ One hypothesis is that external communication channels are merely an extension of within-plant signaling. In sagebrush, lima bean, and poplar, VOCs released from damaged parts of a plant induce resistance in intact sections of the same plant, suggesting that each individual plant uses the signals to coordinate its own physiological responses to protect itself. Karban agrees, saying: ‘The interplant signaling we see may be a result of plants co-opting that process.’ Alternatively, VOC-based signaling between plants may have been…