Seeds of South Australia
Gahnia deusta (Cyperaceae)
Heathy Saw-sedge
List of species for Gahnia
Click on an image to enlarge it
Seed collecting:
November to February
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
SUMMARY
Bridgewater (NCP01)Naracoorte Coastal Plain
 Rare   (IUCN: RA d(i,ii))   [edge of range]
Lucindale (NCP03) 
 Near Threatened
Tintinara (NCP04) 
 Least Concern
Kangaroo Island (KAN01)Kanmantoo
 Near Threatened   [limestone sp; limited habitat]
Fleurieu (KAN02) 
 Near Threatened
Mount Lofty Ranges (FLB01)Flinders Lofty Block
 Vulnerable   (IUCN: VU D2)   [limestone sp; Aldinga Scrub]
Broughton (FLB02) 
 Endangered   (IUCN: EN D)   (Definite Decline)   [3 plants known, grazing a threat]
Southern Yorke (EYB01)Eyre Yorke Block
 Least Concern   (Probable Decline)
St Vincent (EYB02) 
 Least Concern   (Probable Decline)
Eyre Hills (EYB03) 
 Least Concern   [limestone, rocky areas]
Talia (EYB04) 
 Least Concern   [limestone, rocky areas]
Eyre Mallee (EYB05) 
 Least Concern   [limestone, rocky areas]
Murray Mallee (MDD02)Murray Darling Depression
 Least Concern
Murray Lakes and Coorong (MDD03) 
 Near Threatened   [edge of range; mallee limestone spp]
Lowan Mallee (MDD04) 
 Least Concern
IBRA regions
DISPLAY ALL
3 of 4 subregionsNaracoorte Coastal PlainLeast Concern
, Near Threatened
, Rare
2 of 2 subregionsKanmantooNear Threatened
2 of 6 subregionsFlinders Lofty BlockVulnerable
, Endangered
5 of 5 subregionsEyre Yorke BlockLeast Concern
3 of 6 subregionsMurray Darling DepressionLeast Concern
, Near Threatened
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. Deusta from Latin 'deustus' meaning burned; possibly alluding to it being more abundant post fire.
Distribution:
Found in the southern part of South Australia, except in the lower South-east, growing on calcareous loam. Also found in Western Australia and Victoria.
Status:
Native. Common in South Australia. Very rare in Victoria. Rare in Western Australia.
Plant description:
Tufted perennial sedge to 50 cm high, viscid on younger parts. Leaves and bracts with woolly orifices to the sheaths, blades rigid with involute margins, scabrous downwards and almost pungent-pointed in the upper part. Inflorescence a narrow panicle to 30 cm long, with erect distant branches, spikelets numerous in spike-like clusters with prominent secondary bracts, sheaths black. Flowering between September to November.
Fruit type:
Brown spike.
Embryo type:
Capitate.
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 average, at 76%.
Germination table:
DateResultT0T50Pre-treatment | Germination medium | Incubator: Photoperiod / Thermoperiod
July 201610%84dNA 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 for 6 wks (winter) then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)  /  10 hrs for 6 wks (winter) then 12 hrs (spring)
July 20164%91dNA 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 for 6 wks (winter) then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)  /  10 hrs for 6 wks (winter) then 12 hrs (spring)
July 20164%84dNA 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 for 6 wks (winter) then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)  /  10 hrs for 6 wks (winter) 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 for 6 wks (winter) then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)  /  10 hrs for 6 wks (winter) then 12 hrs (spring)
July 20160%NANA 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 for 6 wks (winter) then 22˚C for 12 hrs, 10˚C for 12 hrs (spring)  /  10 hrs for 6 wks (winter) 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)