Lobelia puberula (downy lobelia)

Downy lobelia is a lesser-known lobelia that is actually the most common blue-flowered lobelia in the Southeast. As the name suggests, its leaves have a soft downy underside. The spires of soft lavender to blue flowers atop 3–5' stems are less crowded than those of great blue lobelia. Blooms from late July into November, typically peaking in late August to early October. Prefers full to part sun and will adapt to most soil types. Lobelias are often considered to be short-lived perennials, but they produce lots of tiny seeds that keep the populaton going if the ground is not mulched heavily. Considered toxic for dogs if ingested. 

Downy lobelia is native to eastern and south central United States, where it occurs in roadside ditches, low and upland woods, riverbanks and other boggy or damp areas. Pollinators such as bees, butterflies, and hummingbirds are attracted to the flowers. Birds, small mammals feed on the seeds. Deer also seem to take a liking to it, so plant where protected from deer browse.

Photo credit: Vicki DeLoach (Flickr)