In 1882, Harvard University and the City of Boston made an agreement. Harvard would transfer ownership of the Arnold Arboretum to Boston, in exchange for several services (like road-building and police protection) and a long-term rental plan. The terms? Harvard has a 1,000-year lease on the land, at a rate of one dollar per year. It's not bad, for JP.
If you've ever wondered "what is this plant?", you can contact the Arnold Arboretum's volunteer-run Plant Hotline. They'll answer any plant-related questions, including plant identification or general plant problems.