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. It can be found in many other places as an introduced species. It is cultivated as an ornamental plant. This species sometimes escapes cultivation and becomes established in the wild. It can be weedy, growing in disturbed habitat such as pastures and roadsides.