It appears from research that plants have intelligence, as they can solve problems and learn from experience. In the book, The Hidden Life of Trees: What they Feel, How they Communicate—Discoveries from a Secret World, by Peter Wohlleben, these claims are supported by authoritative scientific publications.
Trees, it seems, are not isolated individuals. They actually live in communities with complex ecological relationships. These relationships are with organisms of the same species and with organisms of different species, and especially, with the soil fungi, which assist in the transmission of nutrients to plant roots.
Trees of the same species are almost tribal, but they will form alliances with trees of other species to communicate collaboratively through a network, which some have called, the Wood Wide Web. Through this network, trees send chemical, hormonal and slow-pulsing electrical signals, which scientists are just beginning to understand.
According to Jack C Schultz, a professor in the Division of Plant Sciences at the University of Missouri in Columbia, plants "are just very slow animals." He also says that plants move with purpose. They hunt for food, compete for territory, circumvent predators and some even trap prey.
Some decades ago, scientists noticed on the African savannah, that giraffes would move on minutes after feeding on umbrella thorn acacias. These acacias, in response to the nibbling of the giraffes, would produce a toxic substance (ethylene) in their leaves. These trees would also send airborne scents to signal other trees in the vicinity, which would also begin to produce the toxic substance to deter the giraffes from eating their leaves.
Also, according to Peter Wohlleben, beeches, spruce, and oaks all register pain as soon as some creature starts nibbling on them. When a caterpillar takes a bite out of a leaf, the tissue around the site of the damage changes. In addition, the leaf tissue sends out electrical signals, just as human tissue does when hurt. However, the signal is not transmitted in milliseconds, as human signals are; instead, the plant signal travels at the slow speed of a third of an inch per minute.
Trees in cities are often stressed and have much shorter lives. Many experience sleep deprivation, with the constant light sources they experience. According to Daniel Chamovitz of Tel Aviv University in Israel, many plants have other similarities to humans, too, in the way plants experience the world. For example, they can distinguish between light of different colours and they are aware of aromas and of gravity and can sense which way is up or down.
Plants are much more complex than we humans have previously thought, which means that we may need to rethink our treatment and relationships with them.
