Plants of
South Australia
Gahnia filum
Cyperaceae
Chaffy Saw-sedge,
Thatching Grass
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Regional Species Conservation Assessments per IBRA subregion.
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Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
Innamincka
Marla
Marree
Mount Gambier
Oodnadatta
Renmark
Wudinna
Keith
Yunta
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Botanical art

Kath Alcock paintings: 2

Prior names

Schoenus filum

Cladium filum

Baumea longifolia

Common names

Chaffy Saw-sedge

Thatching Grass

Etymology

Gahnia named after Dr. Henricus Gahn, 19th century Swedish botanist and student of Linnaeus. Filum ftom Lating meaning a thread; alluding to its threat-like leaves.

Distribution and status

Found in the southern part of South Australia, fringing saline and subsaline swamps and marshes in damp areas near the coast. Also found in New South Wales, Victoria and Tasmania. Native. Common in South Australia. Common in the others states.
Herbarium regions: Eyre Peninsula, Northern Lofty, Murray, Yorke Peninsula, Southern Lofty, Kangaroo Island, South Eastern, Green Adelaide
NRM regions: Adelaide and Mount Lofty Ranges, Eyre Peninsula, Kangaroo Island, Northern and Yorke, South Australian Murray-Darling Basin, South East
AVH map: SA distribution map (external link)

Plant description

Tussock-forming perennial sedge with culms to 110 cm high and 3 mm diameter. Leaf-blades flat to inrolled, erect to spreading, smooth to finely scabrous, as long as or longer than culm, shorter than inflorescence. Inflorescence very narrow, erect spike to 35 cm long with 2–3 densely clustered pale brown spikelets. Flowering in spring and summer. Fruits are dark brown spike on a long stalk. Seeds are brown narrow ovoid seed to 6 mm long and 1 mm wide. Seed embryo type is capitate.

Seed collection and propagation

Collect seeds between November and March. Collect heads that are dying off, turning dark brown and containing hard dark seeds. Place the heads in a tray and leave to dry for one to two weeks. Then rub the heads with a rubber bung to dislodge the seeds. Use a sieve to separate any unwanted material. Store the seeds with a desiccant such as dried silica beads or dry rice, in an air tight container in a cool and dry place. From one collection, the seed viability was high, at 80%. Seeds germinated to a high level (90%) with no treatment.

Seeds stored:
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LocationNo. of seeds
(weight grams)		Number
of plants		Date
collected		Collection number
Collection location		Date
stored		% ViabilityStorage
temperature
BGA7,500 (10.36 g)15-Nov-2013D151113SL
Southern Lofty		1-Jan-201680%-18°C
Location: BGA — the seeds are stored at the Adelaide Botanic Gardens, MSB — the seeds are stored at the Millennium Seed Bank, Kew, England.
Number of plants: This is the number of plants from which the seeds were collected.
Collection location: The Herbarium of South Australia's region name.
% Viability: Percentage of filled healthy seeds determined by a cut test or x-ray.
Germination table:
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We acknowledge the contributions of the South Australian Seed Conservation Centre, the Botanic Gardens of South Australia, and the Department for Environment and Water.