The Cognitive Capabilities of Plants

Most people would assume plants are simple organisms, only relying on chemical processes to survive and sustain their growth. When viewing their basic functions, such as photosynthesis and reproduction, this appears to be true. It sounds bizarre to say a plant could be qualified to feel emotion, or the emotion of another. Although, looking deeper at plant communication, cognition, behavior, and root systems can reveal their truly complex abilities.

The survival of plants goes beyond their individual selves, with fungi branching the roots of plants together to form mycorrhizal networks. The article, “Multiple control levels of root system remodeling in arbuscular mycorrhizal symbiosis,” by Caroline Gutjahr and Uta Paszkowski explains the system of underground fungi. They specifically mention “arbuscular mycorrhizal symbiosis,” a type of fungi connection that penetrates the cells in the roots of plants, allowing them to exchange information and nutrients through this lifeline.

The plants and fungi each benefit greatly from this connection; it is seen as a healthy relationship to provide prosperity to an environment. The authors describe that the fungi collect nutrients from the plants, like carbon, taking a cut for themselves, then return phosphate and nitrogen. The elements aid plants in their growth, specifically with lengthening roots and creating more branches, allowing them to absorb even more minerals from the soil.

While this partnerships seems to be just a lucky deal, Suzanne Simard discovers the social side of this relationship in her book, Finding the Mother Tree. The author describes the community plants form from this link, providing each other with the proper nutrients when a plant sends a distress signal through the mycorrhizal network.

Simard realized a strange relationship between two plants, studying the link between birch and fir trees. She found that they exchange carbon throughout the year, the tree providing carbon being in the season when they thrive best. With research, she discovered that fir trees are the ones mostly relying on birch, as birch could sustain itself, alone, without the help of fir trees. Simard questioned if the relationship has any extra benefits since this exchange appears to be more one-sided.

This inspired her further studies on how much aid trees will provide each other through the mycorrhizal connections. Simard’s next research focused on fir and pine trees. She infested a Douglas fir tree with spruce budworms, a disease that attacks the tree, eventually killing it. Not only did she discover that the fir trees released a large amount of carbon to their neighbors, but the pine trees formed “defense-enzymes,” just as fast as the fir trees had to attack the disease.

The creation of defensive-enzymes in the pine trees is truly amazing, which appears to be supporting the fir trees in a time of crisis. These plants show behavior similar to the giving nature of humans. This goes further than just a mutualistic relationship, or a simple chemical reaction. People are seen doing the same thing, providing for the ill when they are in need. It creates a community of support like a human society.

Not only that, but the discoveries brought up a lot of questions for Simard at the idea of a familial relationships in trees. The diseased trees also sent carbon to specific neighboring trees, like younger saplings, as they were dying, which the author debates as an “inheritance.” The Douglas firs could be sending out the last of their resources as they decay, supporting younger trees to grow in their absence. She later finds that the Douglas fir trees can recognize their kin and “favor” them, sending extra carbon to those connections.

Simard remarks about both discoveries:

Over millions of years, they’d evolved for survival, built relationships with their mutualists and competitors, and they were integrated with their partners in one system. The firs had sent warning signals that the forest was in danger, and the pines had been poised, eavesdropping for clues, wired to receive messages, ensuring the community remained whole, still a healthy place to rear their offspring.

The forest remarkably resembles a human community. Some may argue it is just a survival mechanism, yet human care is displayed for the same reason. A community such as this supports one another for the benefit of neighbors and future generations, just like people. Plant behavior shows incredible signs of care and empathy for the struggling organisms in their environment.

The most astounding research for further intelligence and cognitive capabilities in plants comes from the Journal of Comparative Psychology. The text, “(Re)claiming plants in comparative psychology,” written by Umberto Castiello, explains the many similarities in human and plant intelligence. The author reveals that plants have embodied cognition, or “a kind of situated cognition that assigns cognition to parts of the body other than to the central nervous system.” As well as extended cognition, or cognition that “extends beyond the physical boundaries of the organism,” and enactivism, the ability to engage with the environment and form relationships.

Even without a central nervous system, they have amazing capabilities. Castiello discusses these more in depth, acknowledging their abilities. As mentioned before, plants can recognize their own species and communicate with them, even creating family-like communities. Plants can retain a short-term memory, learning when stimulation is harmful or not. They make decisions based on risk factors in their environment, like choosing to grow roots in different types of soil or “moving” to more or less shaded area. Plants even interact and send signals to entirely other organisms, like pollinators, too attract them in yet another interdependent relationship.

Overall, the behavior of plants is so much more than just a series of instincts. In reality, at a base level, animals and humans can be seen as having simple chemical reactions just like the average perception of plant habits. Both plant and human display actions of caring for their counterparts, alerting for harm and sharing the extra profits they carry to those in need. The relationships that plants form is so alike to the communities of humans, and our families. The behavior is remarkably similar to human empathy.

References

Paszkowski, U., & Gutjahr, C. (1AD, January 1). Multiple control levels of root system remodeling in arbuscular mycorrhizal symbiosis. Frontiers. Retrieved November 21, 2022

Simard, S. (2022). Finding the mother tree. Random House US.

Castiello, U. (2021). (Re)claiming plants in comparative psychology. Journal of Comparative Psychology, 135(1), 127–141.