Well, the plants may not hear you sneaking up on them, but I bet you never knew that a plant’s “germination and growth could be influenced by sound.” While ingesting a leaf off of a plant may not signal the end, the plant doesn’t necessarily like it.
A study by Heidi Appel and Rex Cocroft of the University of Missouri illustrated that “plants recognize the sound of herbivores feeding on their leaves and use information based on vibrations traveling through their tissues.” These vibrations elicit chemical releases for defense and in turn, increase the flavor and smell profiles of the plant’s terpenes.
This study used a plant in the mustard and cabbage family for experiments, but the same defenses happen in all plants. With the cannabis plant, these chemical responses provide stronger, vibrant smells and colors that are an asset to cultivators.
Appel said that when plants in the experiment felt feeding vibrations before they were eaten by caterpillars, they reacted defensively more frequently than when they didn’t feel the vibrations. Interestingly, the plants could differentiate between chewing sounds and those caused by insect song or the wind.
Thus, we can infer from the evidence that plants respond to vibrations generated by herbivores in an ecological and selectively meaningful way. If this is true than a vibration signaling pathway complements the other identified signaling pathways that depend on electrical, phloem-borne, or volatile signals. Additionally, the study suggests that vibration may signify a mechanism involving long-distance signaling in insect-plant interactions that contribute to the systematic production of chemicals for defense.
This process is where the terpenes come into play. Terpenes are the chemicals released by plants in areas attacked by herbivores or insects. They act as bitter tasting compounds that repel animals and bugs. Monoterpenes help inflorescences to deter insects. Even more bitter, sesquiterpenes are abundant on the leaves of plants and act against animals that would feed on them. Terpenes exude in the resin and bestow it with a viscous, sticky quality that traps and immobilizes insects.
It's amazing how nature works in its own process to enhance the therapeutic benefit of cannabis plants. Next time you see a plant remember that it may not be watching you, but it can undoubtedly hear or feel the vibrations of natural predators.