The High Desert Museum is a great introduction to the geography, climate, vegetation, and animals of the area. I'd highly recommend trying to get there for the walking tour as that's where we learned the most about the vegetation of the high desert. And also trying to catch some of the critter meet & greets, as they have some very neat animals you might not otherwise see up that close (like a porcupine and various raptors!).
This museum is well worth the stop, especially at the front of of your stay in the Bend area.More