Atocion armeria, commonly known as Sweet William catchfly, is a species of plant in the family Caryophyllaceae. Originally a native of Europe, it has become widespread in the United States. A small-growing form is known as a dwarf catchfly. The name comes from the way in which small insects are trapped by the sticky sap exuded onto the stem. Although it has been identified as a carnivorous plant in the past, it is not currently regarded as such.
