Lycopus rubellus, commonly known as Taperleaf Water-horehound, is an herbaceous perennial native to wetland areas such as marshes, swamps, and along streambanks in the southeastern United States. It typically grows to about 3 feet in height and has a spreading habit. The plant produces small, white, tubular flowers arranged in whorls along the square stems during the summer months. These flowers are modest in appearance but can add a delicate texture to wetland gardens. The leaves are lanceolate or narrowly ovate, often with a slightly toothed margin.

Taperleaf Water-horehound is valued for its ability to thrive in wet conditions, making it an excellent choice for water gardens, rain gardens, and naturalized wetland plantings. It is also used for erosion control along waterways due to its spreading habit and adaptability to saturated soils. In cultivation, it prefers full sun to part shade and consistently moist to wet soil conditions. While it is not known for aggressive roots or serious disease problems, it can spread vigorously in ideal conditions and may require management to prevent unwanted naturalization.CC BY-SA 4.0