Gahnia trifida

{{short description|Species of plant}}

{{Use dmy dates|date=July 2019}}

{{Speciesbox

|image = Tussock of Gahnia trifida.jpg

|image_caption = Growing along the shore in Clarence, Tasmania, Australia.

|genus = Gahnia

|species = trifida

|authority = Labill.

}}

Gahnia trifida, the coastal saw-sedge, is a tussock-forming perennial in the family Cyperaceae, endemic to southern Australia.

A herb, sedge or grass-like, with very rough leaf margins and underside. The species grows in dense tussocks, 1.5 metres and 1 metre across, with leaves over 1 metre long and drooping. It is found on white or grey sand, or clay, that may be saline. The leaf blade is inrolled from the margin on the upper surface. Stems are rigid and erect. Branchlets containing the flowering heads emerge from axils at the main bracts. This branchlet has a spike-like arrangement of numerous, yellow or brown, clusters of flowerheads.{{cite book |last1= Rippey|first1=Elizabeth |last2=Rowland (Reinette)|first2=Barbara |title=Coastal plants: Perth and the south-west region |orig-year=1995 |edition= 2nd |year=2004 |publisher= UWA Press |location= Perth |isbn= 1-920694-05-6}}{{FloraBase|name=Gahnia trifida|id=907}}

The species occurs in wetlands of coastal regions in Southwest Australia, South Australia, Victoria, and Tasmania. It is found at Rottnest, an island off the west coast, where it grows near the inland salt lakes. The habitat is moist, often adjacent to creeks and swamps, and may also be saline.{{cite web | url = http://www.flora.sa.gov.au/cgi-bin/texhtml.cgi?form=speciesfacts&family=&genus=Gahnia&species=trifida&iname=&submit=Search | archive-url = https://archive.today/20120630152840/http://www.flora.sa.gov.au/cgi-bin/texhtml.cgi?form=speciesfacts&family=&genus=Gahnia&species=trifida&iname=&submit=Search | url-status = dead | archive-date = 2012-06-30 | title = Gahnia trifida Labill. | work = Electronic Flora of South Australia Fact Sheet | publisher = State Herbarium of South Australia }}

The first description of Gahnia trifida was by Jacques Labillardière in Novae Hollandiae Plantarum Specimen (1805).{{APNI | name =Gahnia trifidi| id =45330 }}Labillardiere, J.J.H. de (1805), Novae Hollandiae Plantarum Specimen 1(12): 89, t. 116

Type: "in capite Van-Diemen."