If intelligence for biological individuals is defined as ‘adaptively variable behaviour within the lifetime of the individual’, distinguished from genetically determined, developmental processes, then it makes sense to describe plant behaviour as intelligent.
It makes sense further to specify the definition for plants. Trewavas accordingly defines plant intelligence as ‘adaptively variable behaviour during the lifetime of the individual’. Examples of this adaptively variable behaviour in plants include directional root growth towards water sources, phototropism (the orientation of a plant towards light) and the release of volatile chemicals as a response to herbivore attack.
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It makes sense further to specify the definition for plants. Trewavas accordingly defines plant intelligence as ‘adaptively variable behaviour during the lifetime of the individual’. Examples of this adaptively variable behaviour in plants include directional root growth towards water sources, phototropism (the orientation of a plant towards light) and the release of volatile chemicals as a response to herbivore attack.

What plant philosophy says about plant agency and intelligence | Aeon Essays
The stunningly complex behaviour of plants has led to a new way of thinking about our world: plant philosophy
