This small and apparently shortlived perennial ranges widely across humid, temperate and tropical regions of the Americas, but it is remarkably uniform, with no recognized segregates; 2n = 26 (FNA 8). Although typically found along small streams in partial shade, it can also occur in various damp upland situations, sometimes growing from dormant seed when soil is disturbed but then disappearing for many years. See FNA 8 and W (with cited literature) for notes on nomenclature at species and family level; arguments can be made for Primulaceae, Theophrastaceae and Samolaceae.