Plants have highly sophisticated sensors

In their experiments, Appel and Cocroft found that recordings of the munching noises produced by caterpillars caused plants to flood their leaves with chemical defences designed to ward off attackers. "We showed that plants responded to an ecologically-relevant 'sound' with an ecologically-relevant response," says Cocroft.

More ominously, back in 2006 she demonstrated how a parasitic plant known as the dodder vine sniffs out a potential host. The dodder vine then wriggles through the air, before coiling itself around the luckless host and extracting its nutrients. Conceptually, there is nothing much distinguishing these plants from us. They smell or hear something and then act accordingly, just as we do.

Plants are supremely adapted for doing exactly what they need to do. They may lack a nervous system, a brain and other features we associate with complexity, but they excel in other areas. For example, despite lacking eyes, plants such as Arabidopsis possess at least 11 types of photoreceptor, compared to our measly four. This means that, in a way, their vision is more complex than ours. Plants have different priorities, and their sensory systems reflect this. As Chamovitz points out in his book: "light for a plant is much more than a signal; light is food."

So while plants face many of the same challenges as animals, their sensory requirements are equally shaped by the things that distinguish them. "The danger for the plant people is that if we keep comparing [plants] with animals we might miss the value of plants," says Hamant.

Conversely, the realisation that we have some things in common with plants might be an opportunity to accept that we are more plant-like than we would like to think, just as plants are more animal-like than we usually assume.
http://www.bbc.com/earth/story/20170109-plants-can-see-hear-and-smell-and-respond