Stachytarpheta mutabilis is a species of flowering plant in the verbena family known by the common names changeable velvetberry,[1] coral porterweed, pink snakeweed, red snakeweed, and pink rat tail.[2] 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.[2]
This species is a perennial herb or subshrub generally growing 10 to 20 centimeters tall, sometimes reaching half a meter. The hairy stems have oppositely arranged leaves. The leaf blades are leathery in texture and oblong or lance-shaped. They measure up to 12 centimeters long. The inflorescence is a narrow spike up to 60 centimeters long. The flowers come in many shades of red and pink,[2] or violet (Stachytarpheta mutabilis var. violacea).
This species sometimes escapes cultivation and becomes established in the wild. It can be weedy, growing in disturbed habitat such as pastures and roadsides.[2]
This plant is an introduced invasive species in Fiji, Hawaii, Queensland, and Singapore.[2]
The flowers are attractive to a variety of insects. The butterflies Ornithoptera priamus poseidon and Papilio ulysses have been observed foraging on the plant, as has the bee Amegilla sapiens.[3] Parts of the plant contain the iridoid glycoside ipolamiide, which inhibits insect predation on the plant.[4]