Achillea umbellata ( Umbellata Yarrow )
ball - forming , semi - evergreeen , carefree and generously blooming perennial for summer . Reaches 8 in tall and about 12 inches wide . White flowerheads form umbels on hairy stem . Silvery gray , hirsute leaves are ovate to pinnate . This heat and drought tolerant perennial has a fiberous etymon system and can become invasive . Divide to keep . Butterflies are attracted to this works ....