Russia and USA have never been really "friends", lets admit it. So we will not be surprised, that one of them (pick your side) secretly developed "The triffids" - plants which can move, produce loads of seeds and such seeds can be spread in the wind.
And yes, these plants seem to be intelligent and use poisonous spit to paralyze their prey (which causes humans to go blind)
During one military training, where the seeds were loaded, something went wrong and triffid seeds were released in stratosphere. So these plants were successfully released to the whole Earth.
The sad news: Humans did not make it. They all died, Jim. (Or, if you cannot accept it, try to accept the fact, that humans very few survived and are so busy fighting off the triffids that they cannot come up with a plan into getting rid of the plants)
Moving on into the future, thousands and thousands of years, even eons, if needed.
It is safe to assume, that some animals did survive the triffids. Now:
- Can I assume that some animals would develop into fighting the triffids?
- Is it plausible to assume, that the "deadly" weapon against the triffids would be salt? They are still plants...
- What threats could such animal have to use salt as weapon against the plants?