One of the more interesting, but not the showiest, summer wild flowers in our garden is the bottle gentian (Gentiana andrewsii). A student surveying flowering in a prairie once made an obvious observational error. They kept waiting for the flower to, well, flower, and it did, but not in the way they expected. The corolla of these flowers never actually opens even though the flower is mature and functional. It takes a pretty hefty pollinator to pull the corolla open to get inside the flower, and the brute around here is the bumblebee. No idea whether the carpenter bee can pollinate the flower or not. At this stage our plants are a bit small in this their 2nd year, and perhaps they are not in the best location as quite a few plants around growing more aggressively that are perhaps providing a bit too much shade. But this is a nice tough little plant and can be combined with shrinking violets.