Iva annua, sumpweed or marshelder, 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.
Iva annua was cultivated by Native Americans over 4,000 years ago in the central and eastern United States and specifically the indigenous peoples of the Kansas City Hopewell culture in present-day Missouri and Illinois, for its edible seed. As the author Jared Diamond notes, the edible parts contain 32 percent protein and 45 percent oil.
However, like its relative ragweed, Diamond notes that sumpweed possesses many objectionable qualities which include being a severe allergen, possessing "a strong odor objectionable to some people and that handling it can cause skin irritation." For these reasons Diamond believes that it was abandoned once more pleasant alternatives (like corn) were available, and by the time Europeans arrived in the Americas, had long disappeared as a crop.
- The Plant List, Iva annua L.
- Biota of North America Program 2014 county distribution map
- Flora of North America, Iva annua Linnaeus, 1753.
- Jared Diamond (2003). Guns, Germs and Steel. New York: Norton. p. 151.
- "Iva annua L.". MissouriPlants.com. Includes photographs.
- photo of herbarium specimen at Missouri Botanical Garden, collected in Missouri in 1995
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