This is a clump-forming perennial which can reach a height of 5' with a 4’ spread.  The foliage is lacy and fine-textured resembling columbine or maidenhair fern. It blooms with tiny, double lilac-pink flowers borne in large, airy, terminal sprays that appear in July and August. The stems are thin and purple and may require staking or other support. It prefers rich, humusy, well-drained soil in light, dappled sun to part shade.