This diploid (2n = 14, 16) spring annual (flowering mostly Apr-May in Ky.) became a common weed across eastern North America after the late 19th Century, when it was "rather rare" and confined to coastal states (Gray 1864, 1889). In Ky. the first report of "arvensis" was in 1914, when Gm noted it was common in pastures and meadows, and had probably been introduced among forage seeds. However, it may also have been the plant called "agrestis" by Short (1828-9; Short et al. 1833): "Cultivated fields and pastures common." In Britain, Boutin & Harper (1991) found that germination of arvensis and hederifolia occurs during fall and early spring, but fall seedlings of arvensis suffered more mortality than those of hederifolia.