My wife and I aren't exactly sure what this is, but it appears to be some kind of sage. Every 2-3 weeks, it explodes with the purple flowers. They fall off after 3-5 days, and the cycle repeats all summer. The bees and butterflies like it. It's kind of a gangly thing, but the flowers are pretty. We've seen other sages in the garden stores and in landscaping, but they have different color leaves and only have a few flowers on them.