|This semi-evergreen, mat-forming perennial makes a good ground cover. Reaches 4 to 6 inches tall and spreads to 12 inches. Leaves are silvery-gray and linear. Flowerheads form small corymbs on short stems in white. Blooms summer to early fall. 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. Somtimes referred to as Achillea umbellata 'Weston'.