Ayapana triplinervis (aya-pana, water hemp) is a tropical American shrub in the Asteraceae family. This plant has long slender leaves which are often used to make a stimulating medicine. It contains Herniarin, a methoxy analog of umbelliferone, while its essential oil contains thymohydroquinone dimethyl ether. The flowers are pale pink and the thin, hairless stem is reddish in color. Tall water hemp is an annual weed, Amaranthus tuberculatus.