A common shoreline plant with bright yellow flowers usually having 5 petals. Blooms May–October. Stems long, trailing, creeping out across the water’s surface, can reroot from cuttings. Leaves shiny, dark green, alternate, variously shaped from oval to narrow and willowlike. Roots are of two types: typical roots that grow downward and take nutrients from the soil, and “air roots” or “breathing roots” that are white, spongy, grow upward, and float—these apparently absorb gases from the air.
Similar species: There are 11 species of Ludwigia in Missouri, which all have 4 petals or, lacking petals, 4 sepals (not 5).