Lobelia dortmanna (Dortmann's cardinalflower or water lobelia) is an aquatic stoloniferous herbaceous perennial aquatic plant with basal rosettes, and flower stalks growing to 70–200 cm tall. The flowers are 1–2 cm long, with a five-lobed white to pale pink or pale blue corolla, produced one to ten on an erect raceme held above the water surface. The fruit is a capsule 5–10 mm long and 3–5 mm wide, containing numerous small seeds.