Please refer here : https://www.publish.csiro.au/SB/SB99037
Quotation: " Key to Species
1. Leaves strictly narrowly linear, up to 2.5 mm wide, glaucous, c. regularly serrate, midrib prominent on abaxial surface and leaves bifurrowed; flowers white to pale pink; in siliceous sands and well-drained soils – *S. graminifolium*
Leaves linear to narrowly oblanceolate, greater than 3 mm wide, pale to dark green, serrations absent or towards apex only, lamina continuous over midrib and leaves not bifurrowed; flowers pink to deep magenta – 2
2. Leaves 4–15 cm long, pale to mid-green, widely spreading to suberect; scape fine (< 2 mm wide), glabrous or glabrescent below lowest flowers; flowers 10–30; in water-retentive, peaty soils of montane to subalpine areas at high altitudes – *S. montanum
Leaves 20–40 cm long, dark green, spreading to erect; scape robust (>2 mm wide), glandular–pubescent beyond lowest flower; flowers 30–120; widespread from coast to alps – *S. armeria*
I hope you already were aware of *Stylidium armeria* and i guess so .
According to the published revision's botanical key i quoted above, this plant looks to have leaves wider than 2.5 mm, yet appears to agree with the rest of the botanical key's features of *Stylidium graminifolium* . As said above, unfortunately the Flora of NSW online PlantNet is not an up to date reference in this *Stylidium* small group of 3 species. So we do not have up to date NSW specific descriptions for these two species and a NSW specific key detailing the distinguishing features between these two species.
If you still affirm this identifes to *Stylidium graminifolium* after i have checked now that you are provided with this information, then i am happy to confirm this *Stylidium graminifolium* albeit with leaves appearing as varying from the description, as wider than 2.5 mm and wider in the middle than strictly narrowly linear. Of course such variations' forms exist and so does introgression and hybridisation exist commonly amongst co-occuring related plants.