My green thumb came only as a result of the mistakes I made while learning to see things from the plant’s point of view.
– H. Fred Ale
We know that plants do, in some way, sense stimuli and actively respond to it. Michael Pollan, in an article in The New Yorker in Dec. 2013 (quoted at length here), notes that while the field of plant neurobiology is a misnomer (as no one argues that plants have neurons or brains), plants “have analagous structures. … They have ways of taking all the sensory data they gather in their everyday lives … integrat[ing] it and then behav[ing] in an appropriate way in response. And they do this without brains, which, in a way, is what’s incredible about it, because we automatically assume you need a brain to process information.'”
Pollan characterises the proponents of plant neurobiology as those who “believe that we must stop regarding plants as passive objects—the mute, immobile furniture of our world—and begin to treat them as protagonists in their own dramas, highly skilled in the ways of contending in nature.” After all, he reminds us, “plants dominate every terrestrial environment, composing ninety-nine per cent of the biomass on earth. By comparison, humans and all the other animals are, in the words of one plant neurobiologist, ‘just traces.'” (Which reminds me of Michel Houellebecq‘s wonderful novel, The Map and the Territory.)
Studies have suggested that plant growth can be influenced by sound and that they respond to wind and touch; in fact, they have “between fifteen and twenty distinct senses, including analogues of our five: smell and taste (they sense and respond to chemicals in the air or on their bodies); sight (they react differently to various wavelengths of light as well as to shadow); touch (a vine or a root ‘knows’ when it encounters a solid object)” and, as recently discovered, sound: plants respond to the sounds that caterpillars make when eating plants by unleashing defenses against the predator. It’s been known for some time that some plants, when a predator such as a caterpillar attacks them, emit a chemical distress signal that the caterpillar’s predator, a predatory wasp, follows to the plant. And it may even be that plants have a kind of memory and can learn from experience (see the mimosa experiment mentioned here).
Whether plants exhibit what we would consider learning, consciousness, and intelligence (does intelligence require an organic or physical brain, or is it basically the ability to solve problems?), or whether it’s all done by chemical and electrical pathways is still in question, but it’s clear that they actively sense and respond to their surroundings.
Sometimes when I wander the garden, I like to think about what the plant senses:
Brush-footed butterflies, using their two tiny, bristly front legs to smell and taste the nectar —
giant bumblebees, large moths, and small birds coming in for a heavy landing —
dragonflies, zooming past, then landing, lingering, mating —
frenetic pollinators dancing and crawling around, their legs, antennae, and proboscises tickling nooks and crannies —
grasshoppers, caterpillars and beetles munching and crunching on their foliage and flowers —
heavy rain waterlogging them and bending them to the ground, or filling their channels, ducts, saucers and perforations with awaited refreshment —
me cutting their stems (gathering cut flowers), tearing off their fruits (harvesting), beheading them (removing spent blossoms), hacking off their limbs (pruning).
I talk to them, in a breezy conversational way, as I stroll, more for my sake than theirs, really.