Great Blue Lobelia is one of my favorite North Carolina wildflowers. Lobelia siphilitica is in the Campanulaceae family. Here in our area, it blooms most of the summer through fall in partially sunny, moist areas. The height is usually between 2-3 feet with blue-purple blooms. Lobelia can reseed in a very short time in the right conditions, so you don't need many of these plants to establish a nice clump in the home garden in our area. This lobelia is a native wildflower throughout the northeast; southeast through Texas; and through the midwest to the Rockies. It is native around Ontario and Manitoba, Canada. Great Blue Lobelia is endangered in Massachusetts and vulnerable in New York.
I took this fall photo of the lobelia at the North Carolina Botanical Garden, a conservation garden, in Chapel Hill.