Phyllostegia hillebrandii, commonly known as Hillebrand's phyllostegia, is an extinct species of flowering plant in the mint family, Lamiaceae. The name was first used by Horace Mann Jr. in a list of Hawaiian plants published in 1869.[1] It was first described (posthumously) by William Hillebrand in his Flora of the Hawaiian Islands, published in 1888.[2] The species is thought to have gone extinct, although this can't be officially ruled out.[3] It was endemic to the island of Maui, primarily the eastern region, where it was threatened by alien invasive species and deforestation. The last specimens were collected sometime before 1871.[4]