Historical taxonomy and a resolution of the Stylidium graminifolium complex (Stylidiaceae) in Tasmania

The troubled taxonomic history of Stylidium graminifolium Sw. ex Willd. (syn. Candollea serrulata Labill.) is reviewed. The entity formerly known as S. graminifolium forms a complex consisting of three species. Stylidium graminifolium sens. str. is lectotypified on the basis of plants collected by Banks and Solander from Botany Bay NSW in 1770. This narrow-linear-leaved species is diploid (2n = 30) and is distributed widely on infertile soils in south-eastern continental Australia and Tasmania. Stylidium armeria Labill., on the basis of plants collected from southern Tasmania in the late 1790s, is a tetraploid (2n = 60), with leaves about two to three or four times wider than in S. graminifolium and more spathulate in shape. It has a strictly littoral habitat along the rough water coasts of Tasmania from Macquarie Heads to Tasman Peninsula, probably extending to the coasts of south-eastern Australia. Stylidium melastachys R.Br., on the basis of plants collected from the Kent Group in Bass Strait in 1803, is synonymous with S. armeria. A third species, S. dilatatum W.D. Jackson and R.J.E. Wiltshire, is described as new. It is morphologically similar to S. graminifolium but has linear leaves about two to three times as wide as S. graminifolium and is a tetraploid (2n = 60). It is widely distributed in Tasmania and in the cooler subalpine areas of south-eastern Australia but is confined to more fertile soils than the soils in which S. graminifolium is found.