This weedy annual diploid (2n = 18) is widespread across North and Central America. As with the earlier flowering Erigeron annuus, Conyza canadensis appears to have increased greatly in Ky. to become a major problem after settlement. In 1914, Gm noted: "in cultivated ground and in grass land of almost any sort... often exceedingly common... difficult to get rid of because it is so prolific..."