Gahnia trifida, commonly known as Coastal Saw-sedge, is a tussock-forming perennial sedge endemic to coastal and sub-coastal regions of southern Australia, including Southwest Australia, South Australia, Victoria, and Tasmania. It thrives in wetlands, often adjacent to creeks and swamps, and is particularly adapted to saline conditions, growing on white or grey sand or clay soils. This species was first described by Jacques Labillardière in 1805.

Coastal Saw-sedge forms dense tussocks up to 5 feet tall and 3 feet across, with very rough leaf margins and undersides that can be sharp to the touch. The plant’s appearance is characterized by its long, arching leaves and tall flowering spikes. It produces brownish flower spikes that rise above the foliage, typically in the warmer months, which are not particularly showy but are of ecological importance for habitat. In cultivation, Gahnia trifida is valued for its ability to stabilize soils and for its use in habitat restoration projects, particularly in areas with saline soils. It is also used in ornamental plantings for its textural contrast and as a feature in water-wise gardens. Coastal Saw-sedge prefers full sun to part shade and requires consistent moisture, especially in drier climates. It is generally low-maintenance but may need management to prevent it from becoming too dense or spreading beyond the desired area. While it has no major disease issues, its sharp leaves can be a handling hazard.CC BY-SA 4.0