|Named for its small pearl-like, well-formed, double white flowerheads. Seed raised blooms may be variable in size and shape. Blooms from early to late summer. Hardy and strong rhizome producing perennial with simple, toothed, lance-shaped dark green leaves. Reaches 30 inches tall. This heat and drought tolerant perennial has a fiberous root system and can become invasive. Divide to maintain. Butterflies are attracted to this plant. Good cut flower that dries well, too.