Plant movements have been scientifically investigated since the time of Charles Darwin, who researched the 'Movements and Habits of Climbing Plants'. (ref)

Recently, various experimental studies have suggested not only that many plants have a form of 'proprioception' (i.e. an 'awareness' of the physical position of their own tissues - ref.) but that they are also 'aware' of the position of nearby objects.

So, for example, some climbing plants seem to be able to 'sense' the size and solidity of nearby graspable objects (other branches etc) and adjust their explorative tendril sub-movements appropriately before they 'grasp' the object.

A 2020 paper from the Neuroscience of Movement Lab, at the University of Padua, Italy, published in the journal Biochemical and Biophysical Research Communications, noted that :

In human beings, submovements’ production depends on visual and proprioceptive feedbacks of limb position, which are used to make necessary trajectory corrections. But, what sensory modality provides the necessary information to control and adjust online the movement of plants is unknown. It should be noted that plants are physically self-aware so that they can perceive the configuration of their own body"

Source : Biochemical and Biophysical Research Communications, 2020.

As stated in the paper, there is currently no explanation of how this process works. There are hypothetical suggestions that the plants can possibly sense airborne chemical compounds coming from the support plant - or that they might have some form of 'visual' awareness by sensing nearby light levels. See the paper cited above for details.

The fact that plants have been found to be cognitive - in the sense that they can perceive, 'memorise' and adapt to local conditions - has led some research groups to ask the question of whether plants can be considered 'conscious'plugin-autotooltip__plain plugin-autotooltip_bigConsciousness

inexplicable

Does an ant carrying a piece of leaf across the forest floor ‘know’ it’s doing so? Is it conscious? If science could construct a machine as complex as the human brain, would it ‘know’ it existed? Will it oneday be possible to explain consciousness via the laws of physics?.

See, for example, the work of the MINT Lab at the University of Murcia. Spain, which points out :

[there is] a growing body of empirical research that shows that many sophisticated cognitive capabilities traditionally assumed to be exclusive to animals are exhibited by plants too. Yet, if plants can be considered cognitive, even in a minimal sense, can they also be considered conscious?

Source : Consciousness and cognition in plants, Cognitive Science, Volume 13, Issue 2