The name "Trigger Plant" is the broad common name for some 300 plants of the Stylidium genus, almost all Australian natives. This was growing locally in the wild. The stem was about 40cm tall and the flowers are about 2 cm across. The name of these plants arises from the "Trigger" (see notes), a modified fifth petal which springs into action when a pollinator insect lands, grabbing the insect and wiping pollen over it before releasing. Apparently though, some species of these plants are actually carnivorous and digest the insects. More about them here.