Stachytarpheta mutabilis is a species of flowering plant in the verbena family known by the common names changeable velvetberry, coral porterweed, pink snakeweed, red snakeweed, and pink rat tail. It is native to Mexico, the Caribbean, and South America. This plant is an introduced invasive species in Fiji, Hawaii, Queensland, and Singapore. It is cultivated as an ornamental plant.
This species is a perennial herb or subshrub. The flowers come in many shades of red and pink and are attractive to a variety of insects.