Stylidium ensatum is a dicotyledonous plant that belongs to the genus Stylidium (family Stylidiaceae) that was described as a new species by A.R. Bean in 2000, though the taxon had been noted by Rica Erickson in her discussion of S. muscicola variation in 1958. The specific epithet ensatum is from the Latin ensatus, meaning sword-like, which refers to the shape of the floral throat appendages of this species. It is an erect annual plant that grows from 14 to 22 cm tall. Obovate or orbicular leaves, about 6-17 per plant, are scattered along the stems. The leaves are generally 7-12 mm long, 5.5-12 mm wide, and lack petioles. This species generally has one to three scapes and cymose inflorescences that are 8-16 cm long. Flowers are pink or mauve. S. ensatum is endemic to the area around Darwi