A summer day in the mountains is chock full of decisions. Which spectacular trail should you hike or bike? What’s the best trail lunch to pack? If you see a bear, should you make noise or freeze? (Since we only have black bears in Colorado… make noise!)
No matter what you choose, it’s impossible to miss the amazing explosion of plant life all around us. In the summertime, our hills are green and lush, bursting with dazzling green aspen leaves and the many unique, vibrant wildflowers like columbine and scarlet gilia that call these mountains home.
Despite all that life, it’s easy to think of these plants as nothing but mechanical. We usually don’t see them move, and they don’t have anything we recognize as a brain. But every single day, plants are actively making a whole slew of decisions: where to grow branches and roots, when to send out warning signals, how to allocate resources like water and sugar, and much more. In the extreme conditions of the Rocky Mountains, plants must be especially hardy to survive; every choice is even more important.
But what does it mean for a plant to “make a choice?” Unsurprisingly, no one can agree!
Here’s what we know for sure: plants have senses, lots of them. For example, they can sense gravity in order to grow their roots down into the earth and shoots up into the sky and have receptors to “see” light and grow toward it. They can detect temperature, scents, tastes (like the taste of deer spit!), touch, sounds, and much more. All of these senses equip plants with information about their surroundings that enables them to make choices, just like we do.
“Decisions” like whether to grow a branch or store energy in roots are made by plants through a combination of sensory inputs and hormonal signals that trigger or inhibit growth. But as fine-tuned as this growing system is, I wouldn’t call this an example of plant choice. Do we “choose” how to grow hair?
But there’s evidence from new research that suggests plants do more than just grow in these efficient but automatic ways.
For example, scientists have found that the roots of plants will grow differently as conditions on the ground change. Instead of blindly groping in the soil, roots can choose to change their growing path to avoid competitors–even if that means missing a nutrient hot zone.
Scientists think, too, that plants can make the decision to help out their neighbors rather than always choosing to outcompete them. Some trees–including aspens, which share a root system–seem to send nutrients through their roots to sick or young trees nearby, rather than hoarding those resources for their own growth. In addition, trees can make informed decisions about resource usage that suggests a kind of plant memory: after a drought, plants will close their pores in advance of the next year to preserve water. Trees are natural conservationists!
The discovery that plants could be making active, personal decisions about how to grow and distribute nutrients has amazing implications: it could mean that plants aren’t just living machines, but intelligent beings with unique knowledge about their own homes. If this is true, we could serve to listen to this plant expertise, especially as we seek to protect forests in an era of climate change.
It seems that, by making decisions, plants are constantly balancing their own needs with the health of neighboring trees to support the overall health of the forest. We could learn a lot about how to manage our beautiful forests by listening to plants!
Ella Spungen is a Naturalist at Walking Mountains who loves to talk to plants, even if they can’t talk back (yet).