Common Pigweed

🇺🇸 History in the United States

Unlike most of America's allergenic weeds, common pigweed is a New World native, originating in tropical and central North America and present on the continent long before European settlement. It was formally described by Linnaeus in 1753 in Species Plantarum, by which time it had already crossed the Atlantic to Europe. Its great expansion within the United States came with the plow: as forests were cleared and prairie broken for agriculture through the 18th and 19th centuries, this disturbance-loving annual spread from its original range to fill farm fields, feedlots, and roadsides from the Atlantic to the Pacific and from Canada to Mexico. Settlers gave it the name pigweed because it flourished in hog lots and barnyards, and by the late 19th century it ranked among the most serious crop weeds in American agriculture, a status it retains today. When systematic pollen surveys began in the United States in the early 20th century — culminating in Oren C. Durham's first national atmospheric pollen survey published in 1929 — amaranth pollen was consistently recorded as a significant component of the late-summer 'weed pollen' load, and pigweed remains a standard component of US allergy testing panels, especially in the plains and western states.