Mitragyna is a genus of trees in the Rubiaceae family. Members of this genus contain antimalarial and analgesic indole alkaloids. Species of this genus include Mitragyna ciliata, Mitragyna ledermannii, Mitragyna parvifolia, Mitragyna speciosa, Mitragyna stipulosa, Mitragyna javanica and Mitragyna inermis. The Rubiacae is the fifth largest family of flowering plants by number of genera, and the fourth or fifth largest by number of species.