Although this aggressive annual or biennial weed from northwestern states is widely adventive in eastern states, there appear to be only three old (1828-1937) records from Ky., all from counties bordering the Ohio Rv. (M). Short & Peter (1835) used the name A. canadensis Michx. for Short's coll. of biennis (PH) from "sandy borders of the Ohio River at Louisville". However, FNA 19 indicated that canadensis belongs under the more northern species, A. campestris L.