Stylidium perpusillum  Stylidium perpusillum, the tiny triggerplant, is a dicotyledonous plant that belongs to the genus "Stylidium" (family Stylidiaceae), that occurs in south west Western Australia. It is an ephemeral annual that grows from 1.5 to 4 cm tall. It bears white flowers with undivided posterior corolla petals that bloom from September to November in its native range. Its habitat has been reported as being sand to clay soils in winter-wet depressions near granitic rocks. "S. perpusillum" is a tropical species endemic to southwestern, Western Australia and is considered to be the smallest species in the genus "Stylidium". Johannes Mildbraed, in his 1908 monograph on the family, described "S. perpusillum" as also being present in Victoria and Tasmania, but all other collections since have only been in Western Australia.