Plants make aspirin when they're distressed

according to new research, sending a form of the compound airborne to signal a health problem to the rest of the tree or to other trees.

The finding may help growers more readily identify plants under stress by monitoring for the airborne distress signal.

Salicylic acid is produced by plants when they are under stress like drought or attack by a fungus or insect. It travels through the plant's vascular system and activates the plant's version of an immune response.

Until the new study, nobody had detected the high values of the airborne version of salicylic acid, which the researchers believe is a way to send the stress signal farther and faster. Leaves on the stressed tree or on nearby trees can detect the methyl salicylate signal and convert it into the immune-response-triggering salicylic acid.

"It's faster to send the volatile form to the other leaves, rather than sending through the plant," Karl pointed out. "It might be a more effective way for the same tree to signal that's what's going on."