Arizona’s rarest orchid, when not in bloom, resembles a blade of grass. It vanishes easily in the lush greenery of the Canelo Hills Cienega Preserve — even to the eyes of the botanists who plant it. On a mild April morning, after a decade of preparation, a group of scientists gathered at a desert wetland cradled in southern Arizona’s hills to reintroduce a federally endangered orchid. Aside from t...