Better write about a pollution disaster brought about by the use of a
new insecticide and a plant able to reduce water infestation with that
substance... or a human disease cured with a distant relative of a
modern plant (there are many plants which significantly increase the
body's immunological response in both humans and plants - camomile,
stinging nettles and other less known). Your archeologist might find an
ancient manuscript with the details of a plague and its cure.
Sorry, if I gave silly ideas.