Seeds of South Australia
Gahnia filum (Cyperaceae)
Chaffy Saw-sedge
List of species for Gahnia
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Seed collecting:
November to March
Herbarium regions:
Eyre Peninsula, Northern Lofty, Murray, Yorke Peninsula, Southern Lofty, Kangaroo Island, South Eastern
NRM regions:
Adelaide and Mount Lofty Ranges, Eyre Peninsula, Kangaroo Island, Northern and Yorke, South Australian Murray-Darling Basin, South East
IBRA regions
Bridgewater (NCP01)Naracoorte Coastal Plain
 Least Concern
Glenelg Plain (NCP02) 
 Rare   (IUCN: RA d(i,ii))   (Probable Decline)
Lucindale (NCP03) 
 Least Concern   (Probable Decline)   [salinity a threat]
Tintinara (NCP04) 
 Least Concern   (Probable Decline)   [salinity a threat]
Kangaroo Island (KAN01)Kanmantoo
 Rare   (IUCN: RA d(ii))
Fleurieu (KAN02) 
 Vulnerable   (IUCN: VU B2ab(i,ii,iii))   (Probable Decline)   [around Victor Harbor; grazed, habitat trashed]
Mount Lofty Ranges (FLB01)Flinders Lofty Block
 Vulnerable   (IUCN: VU B2ab(i,ii,iii))   (Probable Decline)   [coastal waterways; known from Onkaparinga estuary]
Broughton (FLB02) 
 Endangered   (IUCN: EN D)   (Definite Decline)   [<50 plants, Brougton Gorge]
Southern Yorke (EYB01)Eyre Yorke Block
 Least Concern   (Probable Decline)
St Vincent (EYB02) 
 Least Concern   (Probable Decline)
Eyre Hills (EYB03) 
 Near Threatened   [restricted habitats, tolerate salt to a limit]
Talia (EYB04) 
 Near Threatened   [restricted habitats, tolerate salt to a limit]
Eyre Mallee (EYB05) 
 Rare   (IUCN: RA d(ii))   [restricted habitats, tolerate salt to a limit]
Murray Mallee (MDD02)Murray Darling Depression
 Rare   (IUCN: RA d(i,ii))   (Probable Decline)   [edge of range]
Murray Lakes and Coorong (MDD03) 
 Least Concern   (Probable Decline)   [salinity a threat]
Lowan Mallee (MDD04) 
 Rare   (IUCN: RA d(i,ii))   [questionable record]
IBRA regions
4 of 4 subregionsNaracoorte Coastal PlainLeast Concern
, Rare
2 of 2 subregionsKanmantooRare
, Vulnerable
2 of 6 subregionsFlinders Lofty BlockVulnerable
, Endangered
5 of 5 subregionsEyre Yorke BlockLeast Concern
, Near Threatened
, Rare
3 of 6 subregionsMurray Darling DepressionLeast Concern
, Rare
RSCA map:
Regional Species Conservation Assessments per IBRA subregion. Please click the thumbnail map.
AVH map:
Australian distribution map (external link)
SA Census:
Census of South Australian plants (external link)     [genus Gahnia]
Name derivation:
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.
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.
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.
Fruit type:
Dark brown spike on a long stalk.
Seed type:
Brown narrow ovoid seed to 6 mm long and 1 mm wide.
Embryo type:
Seed collecting:
Collect heads that are dying off, turning dark brown and containing hard dark seeds.
Seed cleaning:
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.
Seed viability:
From one collection, the seed viability was high, at 80%.
Seed germination:
Seeds germinated to a high level (90%) with no treatment. 
Germination table:
DateResultT0T50Pre-treatment | Germination medium | Incubator: Photoperiod / Thermoperiod
May-1590%28 d42 d seed coat nicked with scalpel, leached in water 7 d;
1% agar;
Incubated under spring/autumn conditions
May-1588%29 d51 d
1% agar;
Incubated under spring/autumn conditions
May-1580%28 d56 d seed coat nicked with scalpel;
1% agar;
Incubated under spring/autumn conditions
May-1574%21 d56 d 250 mg/L gibberellic acid + 10% smoke water 24 h;
1% agar;
Incubated under spring/autumn conditions
Result: Maximum percentage of germination observed.
T0: Number of days before first germinant observed.
T50: Number of days to achieve 50% germination.
Pre-treatment: The initial treatment that the seeds received prior to placement on germination media.
Germination medium: The substrate that seeds were placed on for the duration of the germination experiment.
Incubator conditions:
Photoperiod: The duration of light exposure that the seeds were subject to during a 24 hour period.
Thermoperiod: The constant or diurnal temperatures that seeds were subject to during a 24 hour period.
Winter conditions: 15°C 20 h (3am→11pm); 5°C 4 h (11pm→3am) / 10 h light (8am→6pm); 14 h dark (6pm→8am)
Spring/Autumn conditions: 22°C 12 h (8am→8pm); 10°C 12 h (8pm→8am) / 12 h light (8am→8pm); 12 h dark (8pm→8am)
Summer conditions: 30°C 14 h (6am→8pm); 15°C 10 h (8pm→6am) / 14 h light (6am→8pm); 10 h dark (8pm→6am)