This variable annual (2n = 28-90) is an alien that has become widespread in eastern states on moist to damp fertile soils, often weedy in gardens and among buildings. It was recorded in Ky. (or nearby) as early as the 1830s (Rafinesque 1833, Short et al. 1833). However, the species has not generally spread into native vegetation. Moreover, it may be consumed to a relatively high degree by mammalian herbivores; there is traditional use in Asia as fodder for livestock and for human food and medicine (e.g. Hanelt et al. 2001: page 2414). Colls. from BELL, CARL, HARD (KY, MUR) and probably elsewhere are referable to var. ludens (Miq.) C.B. Clarke. That variety is not recognized in most recent treatments (FNA 22), but see Tucker (1989).