Gravel root is a North American marsh plant in the daisy family that was well known to Native American culture. Depending on locale, the herb was known by any of several common names, including Hemp Weed, Joe-Pye Weed, Queen of the Meadow and Trumpet Weed. Although gravel root produces highly fragrant, showy flower heads, the herb is harvested for its root. Gravel root is characterized as bitter and astringent, which is due to the presence of volatile oils and a crystalline substance called euparin. For the most part, gravel root is used to produce tinctures and extracts.