Great Blue Lobelia (Lobelia siphilitica L) is a native perennial plant to the Eastern half of the United States. It is a woodland plant that prefers part-sun and even moisture. (Do not allow to fully dry out or it starts to get "crispy.") It grows to about 1-3 ft high. It tolerates most any soil type -- heavy clay to sandy.
When I lost a huge oak tree in my backyard a couple years ago, I started to seek out plants to replace my deep shade garden there and this has made a great transition plant.
The Great Blue Lobelia is a good plant for attracting pollinators with its brilliant blue-violet flowers in mid-late summer when many other things in the garden are starting to flag.
To propagate it, divide clumps in the spring. I received mine as a division at a local garden club plant swap. It does also re-seed a bit especially in a damp yard, but it is very easy to pull.