Ambrosia artemisiifolia, common ragweed, is the most widespread plant of the genus Ambrosia in North America. It has also been called annual ragweed, bitterweed, blackweed, carrot weed, hay fever weed, Roman wormwood, stammerwort, stickweed, tassel weed, and American wormwood. It is native to North America but a widespread and common invasive weed in much of South America, Australia, and Eurasia. (source)