This tetraploid (2n = 28) was first reported by Short (1837): "within the last year or two has made its first appearance in this neighborhood, where it is rapidly over-running the lots and commons around Lexington and is likely soon to become a pestiferous weed." Gm noted in 1914: "a very common pasture weed... also in clover and alfalfa meadows. Commonly observed on waste land. Locally abundant."