Coast Saw-sedge,
Cutting Grass
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Regional Species Conservation Assessments per IBRA subregion.


Least concern
Near threatened
Rare
Vulnerable
Endangered
Critically endangered
Extinct
Data deficient
Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
Innamincka
Marla
Marree
Mount Gambier
Oodnadatta
Renmark
Wudinna
Keith
Yunta
Display IBRA region text
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] |
4 of 4 subregions | Naracoorte Coastal Plain | Least Concern , Near Threatened |
2 of 2 subregions | Kanmantoo | Least Concern , Rare |
3 of 6 subregions | Flinders Lofty Block | Rare , Endangered |
3 of 5 subregions | Eyre Yorke Block | Rare , Vulnerable |
3 of 6 subregions | Murray Darling Depression | Rare , Vulnerable |
Warriner (SSD04) | Simpson Strzelecki Dunefields | Endangered (IUCN: EN D) [very small numbers; large plant; could be declining] |
4 of 7 subregions | Stony Plains | Endangered |
Botanical art
Kath Alcock painting: 1
Prior names
Cladium trifidum
Common names
Coast Saw-sedge
Cutting Grass
Etymology
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 3-fid style.
Distribution and status
Found mainly in southern South Australia, with a disjunct population further north, growing on the margins 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. Native. Common in South Australia. Rare in New South Wales. Common in the other States.
Herbarium regions: Lake Eyre, 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 Arid Lands, South Australian Murray-Darling Basin, South East
AVH map: SA distribution map (external link)
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, yellowy to dark brown to black. Flowers in Spring. Fruits are light brown dense spike. Seeds are black three-sided ovoid seed to 3 mm long and 1.3 mm wide, with a fine pitted surface. Seed embryo type is capitate.
Seed collection and propagation
Collect seeds between December and February. Collect heads that are dying off and turning brown with obvious hard black 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 three collections, the seed viability was average to high, ranging from 55% to 100%.
This species has morphophysiological dormancy. The combination of dry heat (90 - 100°C) for 15 min, hydrogen peroxide and gibberellic acid treatments increased germination levels.
Seed collection and germination research for this species was supported by AMLR NRM in 2017-2018 and 1,500 plants will be propagated for reintroduction to Stipituris CP in 2019.
Location | No. of seeds (weight grams) | Number of plants | Date collected | Collection number Collection location | Date stored | % Viability | Storage temperature | BGA | 1,100 (1.29 g) | 6 | 23-Jan-2007 | DJD752 Kangaroo Island | 1-Aug-2007 | 95% | -18°C |
BGA | 2,950 (4.42 g) | | 1-Feb-2008 | Bryan Haywood South Eastern | 19-Sep-2008 | 100% | -18°C |
BGA | 11,000 (14.89 g) | 40+ | 18-Feb-2016 | DJD3328 South Eastern | 2-May-2017 | 55% | -18°C |
BGA | 5,400 (8.57 g) | | 25-Feb-2016 | D250216SL Southern Lofty | 2-May-2017 | 85% | -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:
Display
Date | Result | T0 | T50 | Pre-treatment | Germination medium | Incubator: Photoperiod / Thermoperiod |
Jul-16 | 52% | 91 | 203 |
dry heat 90°C oven 15 min, 30% hydrogen peroxide 20 min, water rinse; 1% agar; / Incubated under winter conditions for 6 weeks then moved to spring/autumn conditions |
Mar-17 | 40% | 35 | NA |
dry heat 100°C oven for 15 min, 30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 24 h; 1% agar; Incubated under spring/autumn conditions |
Sep-17 | 37% | 100 | NA |
dry heat 100°C oven for 10 min, 30% hydrogen peroxide for 20 min, water rinse, leached in water with apple piece (ethylene) 4 d; 1% agar; Incubated under summer conditions |
Mar-17 | 34% | 28 | NA |
dry heat 90°C oven for 15 min, 30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 24 h; 1% agar; Incubated under spring/autumn conditions |
Sep-17 | 23% | 100 | NA |
dry heat 100°C oven for 10 min, 30% hydrogen peroxide for 20 min, water rinse, leached in water 4 d; 1% agar; Incubated under summer conditions |
Jul-16 | 6% | 98 | NA |
dry heat 90°C 15 min, 30% hydrogen peroxide 20 min, water rinse, 10% smoke water + 500 mg/L gibberellic acid 24 h; 1% agar; / Incubated under winter conditions for 6 weeks then moved to spring/autumn conditions |
Mar-17 | 6% | 56 | NA |
30% hydrogen peroxide for 20 min, water rinse, wet heat boiling water poured over and allowed to cool, 500 mg/L gibberellic acid for 24 h; 1% agar; Incubated under spring/autumn conditions |
Jun-17 | 6% | 56 | NA |
30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 44 h; 1% agar; Incubated under summer conditions |
Jun-17 | 6% | 48 | NA |
30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 44 h; 1% agar; Incubated under summer conditions |
Jun-17 | 6% | 28 | NA |
dry heat 100°C oven for 10 min, 30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 44 h; 1% agar; Incubated under spring/autumn conditions |
Jun-17 | 3% | 84 | NA |
dry heat 100°C oven for 10 min, 30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 44 h; 1% agar; Incubated under summer conditions |
Jun-17 | 3% | 28 | NA |
30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 44 h; 1% agar; Incubated under winter conditions |
Jul-16 | 2% | 84 | NA |
30% hydrogen peroxide 20 min, water rinse, 500 mg/L gibberellic acid 24 h; 1% agar; / Incubated under winter conditions for 6 weeks then moved to spring/autumn conditions |
Jul-16 | 0% | NA | NA |
30% hydrogen peroxide 20 min, water rinse; 1% agar; / Incubated under winter conditions for 6 weeks then moved to spring/autumn conditions |
Jul-16 | 0% | NA | NA |
30%hydrogen peroxide 20 min, water rinse, 10% smoke water 24 h; 1% agar; / Incubated under winter conditions for 6 weeks then moved to spring/autumn conditions |
Jul-16 | 0% | NA | NA |
30%hydrogen peroxide 20 min, water rinse, 10% smoke water 24 h; 1% agar; / Incubated under winter conditions for 6 weeks then moved to spring/autumn conditions |
Mar-17 | 0% | NA | NA |
dry heat 50°C oven for 7 d, 500 mg/L gibberellic acid for 24 h; 1% agar; Incubated under spring/autumn conditions |
Jun-17 | 0% | NA | NA |
30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 44 h; 1% agar; Incubated under spring/autumn conditions |
Jun-17 | 0% | NA | NA |
dry heat 100°C oven for 10 min, 30% hydrogen peroxide for 20 min, water rinse, 500 mg/L gibberellic acid for 44 h; 1% agar; Incubated under winter 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)