You could do a simple experiment in which a plant is hooked up to a polygraph machine, and a researcher gets a series of notes, 5 of which say “Do not burn the plant”, and a sixth of which say Do burn the plant. You could randomize them per whatever protocol is currently in vogue. You could even put the researcher in a separate room, from which no conceivable hormonal transmitter could emerge to affect the plant, although I think it might be important for the researcher to be able to SEE the plant. You could ignite the flame remotely.
I think the results would be strong and consistent, and utterly inconsistent with current biological paradigms of life.
As I say often with regard to our political world., there will come a time, hopefully, when we wake up and wonder how so many people could have been so stupid for so long.