Stachytarpheta cayennensis is a species of flowering plant in the verbena family known by many English language common names, including blue snakeweed, Cayenne snakeweed, dark-blue snakeweed, bluetop, nettle-leaf porterweed, rattail, rough-leaf false vervain,[2] blue rat's tail, Brazilian tea, Cayenne vervain, false verbena, joee, nettleleaf velvetberry,[3] and Cayenne porterweed.

It is known in many other parts of the world as an introduced species, including regions in Africa, India, Indonesia, Australia, Florida in the United States, and many Pacific Islands.

The blades are up to 8 to 10 centimeters long, oval in shape with sharply toothed edges, and rough-textured or wrinkly on the upper surfaces.

It may be a casual weed, a "garden thug", a crop pest, or an invasive species with effects on the local ecosystem.

[3] Methods of control include keeping the plants cut down or pulling them up, taking care to remove the large roots.

Several Latin American peoples recognize extracts of the plant as a treatment to ease the symptoms of malaria.

The boiled juice or a tea made from the leaves or the whole plant is taken to relieve fever and other symptoms.