 can start to appreciate the very sophisticated biology going on in leaves and flowers. If you think about it, rootedness is a huge evolutionary constraint. It means that plants canât escape a bad environment, canât migrate in the search of food or a mate. So plants had to develop incredibly sensitive and complex sensory mechanisms that would let them survive in ever changing environments.
I mean if youâre hungry or thirsty, you can walk to the nearest watering hole (or bar). If youâre hot, you can move north, if youâre looking for a mate, you can go out to a party. But plants are immobile. They need to see where their food is. They need to feel the weather, and they need to smell danger. And then they need to be able to integrate all of this very dynamic and changing information. Just because we donât see plants moving doesnât mean that thereâs not a very rich and dynamic world going on inside the plant.
3. You say that plants have a sense of smell?
Sure. But to answer this we have to define for ourselves what “smellâ is. When we smell something, we sense a volatile chemical thatâs dissolved in the air, and then react in someway to this smell. The clearest example in plants is what happens during fruit ripening.
You may have heard that if you put a ripe and an unripe fruit together in the same bag, the unripe one will ripen faster. This happens because the ripe one releases a ripening pheromone into the air, and the green fruit smells it and then starts ripening itself. This happens not only in our kitchens, but also, or even primarily, in nature. When one fruit starts to ripen, it releases this hormone which is called ethylene, which is sensed by neighboring fruits, until entire trees and groves ripen more or less in synchrony.
Another example of a plant using smell is how a parasitic plant called dodder finds its food. Dodder canât do photosynthesis, and so has to live off of other plants. The way it finds its host plant is by smelling. A dodder can detect minute amounts of chemicals released in the air by neighboring plants, and will actually pick the one that it finds tastiest! In one classic experiment scientists showed that dodder prefers tomato to wheat because it prefers the smell.
3B. How about hearing?
This is a bit trickier because while loads of research support the idea that plants see, smell, taste and feel, support for plant auditory prowess is indirectly proportional to the amount of anecdotal information we have about the ways in which music may influence how a plant grows.Many of us have heard stories about plants flourishing in rooms with classical music. Typically, though, much of the research on music and plants was, to put it mildly, not carried out by investigators grounded in the scientific method. Not surprisingly, in most of these studies, the plants thrived in music that the experimenter also preferred.
From an evolutionary perspective, it also could be that plants havenât really needed to hear. The evolutionary advantage created from hearing in humans and other animals serves as one way our bodies warn us of potentially dangerous situations. Our early human ancestors could hear a dangerous predator stalking them through the forest, while today we hear the motor of an approaching car.
Hearing also enables rapid communication between individuals and between animals. Elephants can find each other across vast distances by vocalizing subsonic waves that rumble around objects and travel for miles. A dolphin pod can find a dolphin pup lost in the ocean through its distress chirps. Whatâs common in all of these situations is that sound enables a rapid communication of information and a response, which is often movementâfleeing from a fire, escaping from attack, finding family.
But plants are rooted, sessile organisms. While they can grow toward the sun, and bend with gravity, they canât flee. They canât escape. They donât migrate with the seasons. As such, perhaps the audible signals weâre used to in our world are irrelevant for a plant.
All that being said, I have to cover myself hear by pointing ou