Smarty Plants

Surprising to many readers of Leopold’s commentary is that plants have a kind of memory. For example, sunflowers track the sun throughout the day, return to their starting position at night, and anticipate sunrise even in total darkness. Similarly, albizia tree leaves open and close in rhythm with daylight cycles, continuing their movement even when placed in a dark environment.

Elizabeth Van Volkenburgh, professor emerita at the University of Washington, says, “Once people are convinced it’s true, that plants can remember and can communicate, they wonder what else might be going on in the plant world that we haven’t known about. Perhaps these thoughts make people a little bit more careful in their interactions with plants and ecosystems.”

Certain species of seeds were shown to “remember” the daylight conditions their parent plants experienced, which determines when they germinate. In some cases, these memory-driven adaptations last for decades, helping to ensure survival in specific environmental conditions.

Plants as timekeepers

Beyond memory, plants also displayed a remarkable ability to measure time. Some seeds require specific night lengths to trigger germination, demonstrating an internal biological clock. For instance, begonia seeds will not sprout unless nighttime darkness falls below a particular threshold.

Other plants, like bamboo, seem to take timekeeping one step further. Certain varieties bloom and die in synchronization across the globe despite growing in different conditions. This finding suggests an innate, built-in calendar that spans years or even decades.

Plants communicate through chemical signals

Perhaps the most fascinating discovery has been that plants “talk” to one another (and to other organisms) through chemical signals. When attacked by herbivores, plants release airborne compounds that act as distress signals, warning neighbouring plants to activate their defenses. Some even enlist the help of insects. When under threat, certain plants emit chemicals that attract predatory insects to eliminate their attackers.

Many plants use specific chemical compounds to attract pollinators. Some even mimic pheromones or give off scents resembling rotting meat to trick insects into visiting. Others, like the skunk cabbage, generate heat to amplify their scent and attract pollinators.

“Plant leaves not only take up carbon dioxide and release oxygen, but they humidify the air around them and release organic chemicals for a variety of purposes and reasons,” explains Van Volkenburgh.

“Knowing these things may help those trying to grow plants indoors to recognize the integrated functions of roots and leaves and the beneficial effects of growing many species together,” she adds.

What this means for us

Understanding plant “intelligence” can reshape the way we interact with nature. Here’s how these findings can be applied in practical ways.

Better nurturing and relating to plants

If plants are capable of memory and communication, how we care for them matters. Recognizing their ability to respond to environmental cues can help us cultivate healthier, more resilient plant life.

“Recognizing that a plant is alive, not a piece of green plastic, expands awareness of the natural world,” says Van Volkenburgh.

Designing healthier spaces

Urban planners are increasingly implementing research that suggests green spaces improve air quality, reduce stress, and enhance well-being. They’re betting that urban environments that integrate plants with known adaptive behaviours into their designs can benefit residents in multiple ways.

Creating therapeutic environments

The presence of plants has been shown to lower anxiety and boost mood. Understanding plant behaviour could inform how we design healing spaces, such as hospitals and therapy rooms.

“It is clear that plants growing in therapeutic environments improve outcomes for people who are healing,” says Van Volkenburgh. “Understanding how plants live together, even in artificial settings, might make it easier to have these artificial but beneficial plant groupings growing well indoors.”

The bigger picture: rethinking plant intelligence

These findings suggest that intelligence is not exclusive to animals with brains. Plants, bacteria, and fungi all participate in complex communication networks that allow them to adapt and thrive.

Acknowledging this broader definition of intelligence invites us to shift our perspective on the natural world—not as a collection of passive life forms but as a vast, interconnected system of responsive, interactive beings.

Van Volkenburgh believes this research could lead to practical applications, saying, “Previous approaches have weighed toward engineering plants to provide what people need, without knowledge of all the systems within plants that are disrupted by that engineering.

“The approach of plant behaviour researchers has been to discover what plants do and how they do it, leading to awareness that plants are sophisticated biological organisms, just as humans are.”

As plant research continues, we may uncover even deeper insights into their cognitive-like abilities. Recognizing plants as active participants in ecosystems, not just as resources, can help us create more sustainable, healthy, and harmonious environments for both humans and plants alike.

This article was originally published in the June 2025 issue of alive magazine.