Seeds of South Australia
Gahnia trifida (Cyperaceae)
Coast Saw-sedge
List of species for Gahnia
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Seed collecting:
December to February
Herbarium regions:
Lake Eyre, 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 Arid Lands, South Australian Murray-Darling Basin, South East
IBRA regions
SUMMARY
Bridgewater (NCP01)Naracoorte Coastal Plain
 Least Concern
Glenelg Plain (NCP02) 
 Near Threatened   [undercollected ; edge of range]
Lucindale (NCP03) 
 Least Concern   (Probable Decline)   [drying, salinity, quality of habitat in decline]
Tintinara (NCP04) 
 Least Concern   (Probable Decline)   [drying, salinity, quality of habitat in decline]
Kangaroo Island (KAN01)Kanmantoo
 Least Concern
Fleurieu (KAN02) 
 Rare   (IUCN: RA d(ii))
Mount Lofty Ranges (FLB01)Flinders Lofty Block
 Rare   (IUCN: RA d(ii))   (Probable Decline)   [weeds, spraying - threats]
Broughton (FLB02) 
 Endangered   (IUCN: EN D)   (Definite Decline)   [<10 plants]
Olary Spur (FLB03) 
 Endangered   (IUCN: EN D)   (Definite Decline)   [<10 plants]
Southern Yorke (EYB01)Eyre Yorke Block
 Vulnerable   (IUCN: VU A2ac )   (Definite Decline)
Eyre Hills (EYB03) 
 Rare   (IUCN: RA d(ii))   [grazing, restricted habitat]
Talia (EYB04) 
 Rare   (IUCN: RA d(ii))   [grazing, restricted habitat]
Murray Mallee (MDD02)Murray Darling Depression
 Rare   (IUCN: RA d(i,ii))   (Probable Decline)
Murray Lakes and Coorong (MDD03) 
 Vulnerable   (IUCN: VU B2ab(i,ii,iii))   (Probable Decline)
Lowan Mallee (MDD04) 
 Rare   (IUCN: RA d(i,ii))   [outliers]
Warriner (SSD04)Simpson Strzelecki Dunefields
 Endangered   (IUCN: EN D)   [very small numbers; large plant; could be declining]
Oodnadatta (STP02)Stony Plains
 Endangered   (IUCN: EN D)   [in springs]
Murnpeowie (STP03) 
 Endangered   (IUCN: EN D)   [in springs]
Peake-Dennison Inlier (STP04) 
 Endangered   (IUCN: EN D)   [in springs]
Baltana (STP07) 
 Endangered   (IUCN: EN D)   [in springs]
IBRA regions
DISPLAY ALL
4 of 4 subregionsNaracoorte Coastal PlainLeast Concern
, Near Threatened
2 of 2 subregionsKanmantooLeast Concern
, Rare
3 of 6 subregionsFlinders Lofty BlockRare
, Endangered
3 of 5 subregionsEyre Yorke BlockRare
, Vulnerable
3 of 6 subregionsMurray Darling DepressionRare
, Vulnerable
Warriner (SSD04)Simpson Strzelecki DunefieldsEndangered
  (IUCN: EN D)   [very small numbers; large plant; could be declining]
4 of 7 subregionsStony PlainsEndangered
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. Trifida from the Latin 'trifidus' meaning split into three; referring to the style with 3-fid.
Distribution:
Found in mainly in the southern part of South Australia with a disjunct population further north, growing  on the edge of coastal saltmarsh or farther inland near saline and sub-saline lakes and watercourses. Also found in Western Australia, New South Wales, Victoria and Tasmania.
Status:
Native. Common in South Australia. Rare in New South Wales. Common in the other states.
Plant description:
Tussock-forming perennial sedge with culms to 100 cm high and 4 mm diameter. Leaves flat to inrolled, spreading, scabrous, longer than or equalling inflorescence. Inflorescence erect, narrow, to 70 cm long, dark brown to black. Flowers in Spring.
Fruit type:
Light brown dense spike.
Seed type:
Black three-side ovoid seed to 3 mm long and 1.3 mm wide, with a fine pitted surface.
Embryo type:
Capitate.
Seed collecting:
Collect heads that are dying off and turning brown with obvious hard black 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 three collections, the seed viability were average to high, ranging from 55% to 100%.
Seeds stored:
LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA1100 (1.29 g)623-Jan-2007DJD752
Kangaroo Island
1-Aug-200795%-18°C
BGA2950 (4.423 g)1-Feb-2008Brian Haywood
South Eastern
19-Sep-2008100%-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:
DateResultT0T50Pre-treatment | Germination medium | Incubator: Photoperiod / Thermoperiod
July 201652%91d203d Dry heat at 90 degrees C for 15 mins; soak in H2O2 for 20 mins then rinse
1% water agar
15˚C for 20 hrs, 5˚C for 4 hrs (winter) for 6 wks; then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)      /  10 hrs (winter) for 6 wks; then 12 hrs (spring)
July 20166%98dNA Dry heat at 90 degrees C for 15 mins; soak in H2O2 for 20 mins then rinse; soak in 10% smoked water and 500 mg/L GA for 24 hrs
1% water agar
15˚C for 20 hrs, 5˚C for 4 hrs (winter) for 6 wks; then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)      /  10 hrs (winter) for 6 wks; then 12 hrs (spring)
July 20162%84dNA Soak in H2O2 for 20 mins then rinse; soak in 500 mg/L GA for 24 hrs
1% water agar
15˚C for 20 hrs, 5˚C for 4 hrs (winter) for 6 wks; then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)      /  10 hrs (winter) for 6 wks; then 12 hrs (spring)
July 20160%NANA Soak in H2O2 for 20 mins then rinse
1% water agar
15˚C for 20 hrs, 5˚C for 4 hrs (winter) for 6 wks; then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)      /  10 hrs (winter) for 6 wks; then 12 hrs (spring)
July 20160%NANA Soak in H2O2 for 20 mins then rinse; soak in 10% smoked water for 24 hrs
1% water agar
15˚C for 20 hrs, 5˚C for 4 hrs (winter) for 6 wks; then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)      /  10 hrs (winter) for 6 wks; then 12 hrs (spring)
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)