The scientist grew pea plants and placed their roots in containers with different nutrient quantities. They noticed that the plant grew more roots in the pots with more nutrients. From this, they asserted that plants take calculated risks and gamble in which environments to risk their development.
"To our knowledge, this is the first demonstration of an adaptive response to risk in an organism without a nervous system," said researcher Alex Kacelnik. "We do not conclude that plants are intelligent in the sense used by humans or other animals, but rather that complex and exciting behaviors can theoretically be predicted as biological adaptations--and executed by organisms, on the basis of processes evolved to exploit natural opportunities efficiently."
Plants have been thought to feel pain in the past. They have been described to hear caterpillars chew on their leaves and react by defending themselves. They can distinguish the different sounds produced by caterpillars eating their leaves and wind blow through their leaves.
They distinguish this though the vibrations that repel through them. The research is still in their early phase, but what is impressive is that plants have the ability to feel without having a brain. Their reactions are mostly chemical and slow, but this still proves that they are more intelligent than initially thought.