Tiedemannia filiformis, formerly known as Oxypolis filiformis, is a perennial member of the carrot family. It is also known as water cowbane and water dropwort. It is found in wetland habitats and has been documented in much of the Southeastern Coastal Plain from Texas to North Carolina. It grows to about 2-3 feet tall and blooms white flowers in late summer to early fall. It is a larval host for the Eastern black swallowtail butterfly and the flowers attract a wide variety of pollinators.