Though I can't prove it, I'm edging toward the belief they share resources with each other, including water and nutrients through the root system.
All these facts and ideas are easily undone by particularly defining "awareness" and so this is largely a terminological problem.
The discussion quickly becomes, "Define awareness." or ... more generally ... "Define consciousness," which we see with machines, insects, plants, even single celled organisms.
Here's what science does tell us repeatedly: Those things which humans as a species are convinced have no consciousness is decreasing. Most, even today, would not believe an octopus is conscious, but we now think they are. Dolphins. Birds, even fish now have scientific studies indicating they are self-aware.
So, yeah, justifying the eating of plants because they lack self-awareness isn't a valid argument in my book.
That doesn't absolve us of a mission to reduce suffering for the things we eat.
Plants can certainly suffer and it's trivial to identify.
I believe the dog is happy and excited and eager to greet its friend of another species, but many, many people believe that dog is exhibiting purely mechanical behavior driven by instinct alone.
1. see e.g. https://qz.com/1045782/an-octopus-is-the-closest-thing-to-an...