Round the time the Gods called Englishman declared Sunflowers can do what again?
Just kidding. Try back when green algae with flagella first evolved over a billion years ago. As if they were the first to react to their local enviroment, fffs.
Anyone who's ever looked at a plant on a window sill knows they sense light and grow towards it. Likewise outdoors and in reaction to winds and excess heat, etc, as well.
Plant roots in the lab have demonstrated the ability to remember which side of the pot nutrients are concentrated when it is unevenly distributed. Grown in a medium with one side nutrient poor and the other rich then transplanted to one that is balanced throughout, they grow in the direction they had learned to.
Plants can sense when they are being eaten. Yes, we're talking that lettuce your constipated bowels are in dire need of also.
During Gypsy Moth caterpillars outbreaks, affected trees (like oaks) release airborne chemicals that signal to others of the same species that they are under attack. They immediately start to produce chemicals within which are toxic to the pests. While it may be too late for the already under siege trees, the rest might build up enough to repel them when they arrive and survive the onslaught.
That's not just sensing and reacting, that's called communicating, son.
When a blade of grass is cut, an electric signal goes down to its base, prompting it to grow new leaves (yes, lawn mowing promotes lusher growth, as does pruning with other plants)
Venus Flytraps have hairs within the pads that when two are triggered within seconds of each other by touch, send an electric signal to the base where they join, prompting instant growth/divison of a single line of new cells which is enough to close both halves, trapping prey. It then begins to release enzymes which break it down for digestion.
Sense.
Reaction.
Further reaction.
Brain? Nervous system? Not the same as with animals, but an electic signal is being transmitted and recieved and reacted to. If that doesn't sound like sentient to you, you are neither truly aware of your own sentience yourself nor otherwise capable of utilizing that brain that the Great God of Wisdom, Satan, gifted with the ability to think.
Seems you're not that special after all.
Don't blame the messenger, blame the Gods who let them evolve so.