Along with making some recommendations, I’d like to address your comment “Not as a botanical garden curiosity of a formally wild plant, but in its natural habitat so it can continue its evolution in the habitat and wild where it belongs.” Keeping extinct or nearly extinct plants as oddities is something that very few botanical gardens do anymore. Nowadays, numerous public gardens (botanical gardens and arboreta) are leading the fight to keep plants from becoming extinct through numerous conservation, research, and educational activities. Just as one example, here at Coastal Maine Botanical Gardens, we have for eight years been conducting one of the few longitudinal studies in existence of Cypridium acaule – the pink lady’s slipper orchid, of which we have several thousand growing naturally on our grounds. The umbrella organization that covers most public gardens in North America is the AABGA (American Association of Botanical Gardens and Arboreta), within which, there is a committee that oversees the conservation activities engaged in by public gardens. The mission of the AABGA is ”dedicated to promoting people's appreciation and understanding of the irreplaceable value of plants.” See: http://www.aabga.org/public_....7498579
Another organization you should be aware of the BGCI (Botanic Gardens Conservation International) at http://www.bgci.org.uk/
Regarding your career interests, I applaud and admire you for taking an interest in what I believe is a most noble pursuit. You have age on your side and have lots of time to decide exactly what you want to do. In my forties I decided I wanted out of the medical field and wanted instead to spend the rest of my life helping people understand, value and enjoy plants. Some people have recommended you getting a degree in biology. Indeed, this would be good if you wanted to learn about a more diverse litany of subjects in the plant AND animal world. If you were specifically interested in plants, I would go for botany, or plant science. I obtained an undergraduate degree in plant science, and was then awarded a full fellowship for a master’s degree in public garden management at Cornell. The type of subjects I suggest you explore taking are: botany, plant physiology, taxonomy, integrated pest management, water resources, plant pathology, entomology, arboriculture, plant identification courses, geographic information systems, environmental design, soil science, etc. Fortunately I have never had to take physics!
Please contact me if I can answer any questions.