Iva annua, the annual marsh elder or sumpweed, is a North American herbaceous annual plant in the sunflower family. It is native to northeastern Mexico (Tamaulipas) and to the central and southern United States, primarily the Great Plains and Mississippi Valley as far north as North Dakota. There are some populations in the eastern US, but these appear to represent introductions. Iva annua is an annual herb up to 150 cm (5 feet) tall. The plant produces many small flower heads in a narrow, elongated, spike-like array, each head with 11-17 disc florets but no ray florets.