Culver's root is an interesting plant native to the United States. It is a tall upright perennial with spikes of flowers and leaves arranged in whorls. It is pretty tall plant and adds a vertical accent to the back of the flower borders. These plants of mine are planted in the middle of the island-like flower bed that stretches out in the middle of my garden.
The flowers open firstly on the bottom side of the spike and attract lots of bees and butterflies. It requires a medium wet, well drained soil in a full sun. I have transferred my plants from the shady part of my garden 'cause they tend to flop over seeking the sun.
It takes some time to establish in the garden but it is worth waiting for it.