I still learn new things about the plants here all the time, but finding out what most of the plants I've seen can be used for has taken... at least six lunar cycles - months. Traveling around let me see a few plants that don't grow everywhere, and some of them are only useful in certain seasons. It will probably be a long time before I know everything about the plants here, and I only spent a few days in the Kanto region, so there are probably a lot of plants there that I haven't seen yet.