About Oenanthe sarmentosa C.Presl ex DC.
Oenanthe sarmentosa is a species of flowering plant in the Apiaceae family, commonly known as water parsley. It is native to western North America, ranging from Alaska to California, where it grows in wet environments including streambanks. It is sometimes aquatic, growing directly in water. This plant has been cultivated for use in wetlands, but the recent discovery of several established colonies growing along a stream in Illinois shows it can become a noxious weed when introduced to regions outside its native range. It is a perennial herb that reaches a maximum height of around 1.5 meters. Its leaves have blades that can grow up to 30 centimeters long, attached to petioles up to 35 centimeters in length. The parsley-like leaf blade is divided into serrated, lobed leaflets. Its inflorescence is a compound umbel bearing many flowers with petals that range from bright white to red-tinged.
