From philosopher Laura Ruggles at Aeon:
What does it even mean to say that a mallow can learn and remember the location of the sunrise? The idea that plants can behave intelligently, let alone learn or form memories, was a fringe notion until quite recently. Memories are thought to be so fundamentally cognitive that some theorists argue that they’re a necessary and sufficient marker of whether an organism can do the most basic kinds of thinking. Surely memory requires a brain, and plants lack even the rudimentary nervous systems of bugs and worms.
However, over the past decade or so this view has been forcefully challenged. The mallow isn’t an anomaly. Plants are not simply organic, passive automata. We now know that they can sense and integrate information about dozens of different environmental variables, and that they use this knowledge to guide flexible, adaptive behaviour.
For example, plants can recognise whether nearby plants are kin or unrelated, and adjust their foraging strategies accordingly.
…
Plants are a diverse and flexible group of organisms whose extraordinary capacities we are only just beginning to understand. Once we expand the vista of our curiosity beyond animal and even plant kingdoms – to look at fungi, bacteria, protozoa – we might be surprised to find that many of these organisms share many of the same basic behavioural strategies and principles as us, including the capacity for kinds of learning and memory. More.
As noted here earlier, there is no tree of intelligence.
And if intelligence does not even require a brain, that is another blow to materialism, and probably to any kind of naturalism. But then we are told that consciousness is an illusion and information remains unintegrated into science. From there, we are assured, we shall make great progress… as if.
See also: How plants see, hear, smell, and respond without animal sense organs
From the ivied halls: Attack on human “privilege” in relation to plant life
and
Does intelligence depend on a specific type of brain?