|source: What Do Plants Talk About|
Not only can plants “see” light and “hear” vibrations, they are now known to smell parasitic worms. These nematodes communicate with each other using pheromones (specifically ascarosides), which in turn regulate the worm’s development and behavior. We might think of it as wi-fi.
The chemical signal is excreted (or transmitted) from one worm, and received by another. Plants, using that natural tendency of all living things to be clever, hack into the nematode wi-fi network, and use that information to regulate their own behavior and development. When you watch roots grow in timelapse, you realize they're just like worms, wiggling through the ground, looking for nutrients. Only they're not looking, they're smelling.
This should be a reminder to us that the thing we call Smell is a primitive form of communication used by all living things. Plants don't have brains, so they don't smell like we do. But they do have memories, and even autobiographies. We would call this ontological history – these are interactions stored in the ever-changing DNA of the plant. Experience is passed on to subsequent generations.
The first organisms lived in a chemical world. And although they may have been sensitive to light particles and waves of vibration, they were also a receiver of chemical signals. And of the lot, the chemo-signals were the most complex and required the most sophisticated translation. Our brains – real human brains – grew through evolution out of the olfactory bulb. We may associate the advanced cortical functions of our mind with other, higher senses like vision and audition, but that whole thing is undergirded by the primitive nose- brain. “We think because we smell.” (Diane Ackerman, A Natural History of the Senses, 1990)
Our impossibly complex brains can't really fathom what it means for a plant to smell until we come to understand our own chemically-encrypted selves.
Chemo-signal pattern recognition has come a long way, and it’s a history worth looking into.