'The Pearl' has pure white, double flowers. It blooms from early to late summer on stems that stand 18 to 24 inches high. It has small toothed, lance like leaves which are toxic to horses and cattle. This is a cultivar of Achillea ptarmica which is native to Europe. It is attractive to butterflies, bees and hummingbirds while resistant to deer and rabbits. The genus name Achillea is in reference to Achilles, hero of the Trojan Wars in Greek mythology, who used the plant medicinally to stop bleeding and to heal the wounds of his soldiers.