Phenetic analyses of morphological variation within Stylidium graminifolium Sw. ex Willd. sens. lat. are presented. Plants collected from 65 localities throughout Victoria and southern New South Wales were scored for eight leaf and 11 floral characters. Flowers collected from a subset of these populations and preserved in ethanol were scored for 15 floral characters. Five forms were identified in the analyses with three species warranting taxonomic recognition. Stylidium graminifolium Sw. ex Willd. sens. str. has erect, glaucous, narrowly linear leaves up to 2.5 mm wide with regular, fine serrations along the leaf margin. This species has comparatively small, pale pink to white flowers with six prominent and two reduced throat appendages surrounding the entrance to the nectary tube. The scape is usually glandular–pubescent below the lowest flower and bears 10–50 flowers. This species is widespread in eastern Australia in well-drained sandy soils of lowlands and foothills. Stylidium montanum Raulings & Ladiges sp. nov. has suberect to spreading leaves with a fine, reddish scape bearing fewer than 30 deep pink flowers usually with six prominent and two reduced throat appendages. It differs from S. graminifolium in its habit, broader, oblanceolate leaves 3–5(–7) mm wide, pale to mid-green leaves, deep pink flowers and a glabrescent scape below the lowest flower. It occurs on peaty water-retentive soils in alpine and subalpine situations above c. 1000 m. Stylidium armeria (Labill.) Labill. is reinstated. This species is characterised by narrowly oblanceolate leaves (3)5–15 mm wide and 15–40 cm long, a glandular–hairy scape above the lowest flower and 30–110 flowers per scape. Flowers are light pink to deep magenta with eight prominent throat appendages. This species is widespread throughout south-eastern Australia and is morphologically variable throughout its distribution.