Costus L. is the most species‑rich genus in Costaceae and is mainly distributed in the Neotropics and tropical Africa. Five Costus species have been introduced to Java, Indonesia, for ornamental purposes. During our botanical expeditions in Java from January to May 2023, we discovered three previously unreported species of Costus that occur spontaneously in the wild: C. phyllocephalus K.Schum., C. spicatus (Jacq.) Sw., and C. villosissimus Jacq. Their spontaneous populations have been found on roadsides and abandoned areas in West Java.
