Stachytarpheta mutabilis is a species of flowering plant in the verbena family known by the common names changeable velvetberry,[2] coral porterweed, pink snakeweed, red snakeweed,[3] and pink rat tail.

[4] This species is a perennial herb or subshrub generally growing 10 to 20 centimeters tall, sometimes reaching half a meter.

The flowers come in many shades of red and pink,[4] or violet (Stachytarpheta mutabilis var.

[4] This plant is an introduced invasive species in Fiji, Hawaii, Queensland, and Singapore.

The butterflies Ornithoptera priamus poseidon and Papilio ulysses have been observed foraging on the plant, as has the bee Amegilla sapiens.