Ammannia coccinea, commonly known as Valley Redstem or Scarlet Toothcup, is an annual herb that is native to wetland margins, such as riverbanks, pond edges, and marshy areas, primarily in the central and southeastern United States. It is not typically found in the Pacific Northwest or New England. Ammannia coccinea can grow erect up to one meter tall or sprawl along the ground. It has narrow, linear leaves and small, inconspicuous rose to lavender flowers that appear in clusters from late summer to fall. The flowers give way to rounded capsule fruits that are not particularly ornamental. Despite its modest appearance, the plant can be quite resilient and may become weedy in some regions, adapting well to various wet environments.

Valley Redstem is not commonly cultivated in gardens but may be of interest for naturalized wetland plantings or restoration projects due to its adaptability to moist conditions. It thrives in full sun to part shade and prefers wet, muddy, or shallowly flooded soils. While not a major garden feature, it can provide habitat for wildlife, particularly in wetland areas. Gardeners should be aware that it can spread aggressively in suitable conditions and may require management to prevent unwanted colonization.CC BY-SA 4.0