My suspicion got very much confirmed after reading the book "The Hidden Life of Trees" that explores and explains many amazing phenomena and behaviors of trees by a German forest care taker of 20+ years, and my subsequent research on the subject matters.
Trees/plants do communicate with one another, not only through electrical signals (they do have it, transmitting at much slower pace than ours, though), but also through the use of the senses of smell and taste. If a giraffe starts eating an African acacia, for example, the tree releases a chemical into the air that signals that a threat is at hand. As the chemical drifts through the air and reaches other trees, they "smell" it and are warned of the danger. If an insect starts eating the leaf of a tree, for another example, the saliva of the eating insect can be "tasted" by the leaf being eaten. In response, the tree sends out a chemical signal that attracts predators that feed on that particular leaf-eating insect.
And trees are social: they form a "wood wide web" with interconnected roots and soil fungi where they exchange nutrients, transmit/relay warning signals and messages against impeding dangers, take care of sick trees and "dead" stumps (Stumps keep water; without the crowd, hot sun and swirling wind can penetrate to the forest floor and disrupt the moist, cool climate), so they are better together in the long run.
They can "learn" and "remember". The sensitive leaves of Mimosa (the tickle-me-plant) that close up quickly after detecting droplets of water stop doing so after they learn that the repeated disturbance has no real damaging consequence. Trees need to know that warmer days are due to early spring or late summer so they know to grow more leaves if it's the former and drop foliage if it's the latter. They do this by keeping track of ("remembering") the combination of day length and temperature, and "deducing" that rising temperatures mean spring, falling temperatures mean fall.
And if that's not enough already, plants can "hear" too. An experiment by University of Missouri recorded the sound of a caterpillar eating a plant's leaf and played it back to a set of plants, which later generated more mustard oils when attacked by caterpillars to deter them from eating more than another set of plants that were not pre-exposed to the recording.
If plants are so "intelligent", might they also have emotion, or even consciousness? Or have you heard the allegation that talking nice/showing affection to your plants makes them grow better than those you don't?
In a controversial documentary film made in 1978, researchers placed monitoring devices on both a plant and a man next to it watching a stimulus video and charted their responses. They found the needle movement of the plant's graph closely mirrored the man's emotional zig-zagging throughout the whole watching process.
Another experiment used two cabbages... one hooked with electrodes to a machine that converted its energetic expressions into audible tones. When the cabbage that was not hooked up to any instrument was being chopped to pieces by a human scientist, the plant hooked up to the machines was heard screaming or crying, with a very high pitch tone.
A similar, but even eerier experiment had a man chosen at random go into the lab and destroy one of three plants. The other two plants were then hooked up to electro-encephalographs (EEG – brain wave monitors) and they marched the men in one by one. The plants exhibited no alarm, but as soon as the one responsible for the plant death entered the room, the other two plants started registering wildly on the graphs. They knew who it was that killed their friend, so to speak.
Just like all the weeds in my yard know who their Top Enemy Number One is now.
