This is a large and widely adaptable group of herbaceous perennials, noted for their feathery foliage and colorful flowers. Tiny flowers are clustered into broad flat-topped heads and occur late spring through early fall, sometimes year round. Yarrow likes heat and is quite drought tolerant. Tolerant of clay or sandy soil, it is easy to grow and looks particularly good in Mediterranean and rock gardens. Achillea millefolium is native to California.