This East Asian annual is a widespread, variable weed of rice fields, sandy or muddy lake-shores, damp lawns and similar disturbed areas in warmer regions (2n = 12-52). It has been spreading in the eastern USA since the 1930s, perhaps initially recorded in Lou. (SRNEC 2024). In Ky. it was first recorded during the 1970s (BA), and it has now become widely scattered, usually along lake-shores or in damp lawns. The species is often overlooked due to its small size (usually <10 cm). However, ther have been many recent records on iNaturalist.org, especially in hilly regions with sandy soils; the species may remain relatively uncommon in more fertile farmland. Flowering occurs mostly early (Apr-Jun) or late (Sep-Nov) in the growing season.