Gahnia sieberiana, commonly known as the red-fruit saw-sedge, is a tussock-forming perennial plant in the family Cyperaceae, endemic to Australia. It is a widespread plant that favours damp sunny sites. Many insect larvae have been recorded feeding on the red-fruit saw-sedge. It may grow over 2m (07feet) tall.[1]
Gahnia sieberiana was described by German botanist Carl Sigismund Kunth in 1837. It is one of the many species named in honour of the Bohemian collector, Franz Wilhelm Sieber.[1]
Gahnia sieberiana grows as a tall strappy tussock to 2m (07feet) high and wide, with rough flat leaves.[2] The leaf margins have tiny serrations that are sharp and can cut the hands of those handling the plant.[3] The tall black flowers grow in spikes from the centre of the plant and can rise another metre above the clump,[4] appearing in spring and summer. They are followed by shiny red or red-brown round nuts, which measure 2.5to long, 1.5to in diameter.[2]
Gahnia sieberiana is found across eastern Australia, from Tasmania to North Queensland, as well as Malesia, from sea level to an altitude of 1200m (3,900feet).[3] It is found on clay and sandy soils.[5]
Seeds appear to germinate after bushfire.[5] The caterpillars of the dingy grass-skipper (Toxidia peron), montane sedge-skipper (Oreisplanus perornata), silver sedge-skipper (Hesperilla crypsargyra), flame sedge-skipper (Hesperilla idothea), golden-haired sedge-skipper (Hesperilla chrysotricha), heath sand-skipper (Antipodia chaostola), sword-grass brown (Tisiphone abeona)[5] and northern sword-grass brown (Tisiphone helena) feed on the leaves.
For Australian gardens, Gahnia sieberiana has been suggested as a native replacement for pampas grass (Cortaderia selloana), which is a noxious weed there.[4] Cultivation is hampered by difficulties in propagation by seed. Clumps can be divided to make more plants.[4]