Seeds of South Australia
Duma horrida ssp. horrida (Polygonaceae)
Spiny Lignum
List of species for Duma
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Seed collecting:
July to December
Herbarium regions:
Gairdner-Torrens, Murray, South Eastern
NRM regions:
South Australian Arid Lands, South Australian Murray-Darling Basin, South East
IBRA regions
Broughton (FLB02)Flinders Lofty Block
 Critically Endangered   (IUCN: CR D)
Murray Mallee (MDD02)Murray Darling Depression
 Vulnerable   (IUCN: VU B2ab(i,ii,iii))   (Probable Decline)   [restricted to river; naturally rare]
Murray Lakes and Coorong (MDD03) 
 Rare   (IUCN: RA d(ii))   (Probable Decline)
Murray Scroll Belt (RIV06)Riverina
 Vulnerable   (IUCN: VU B2ab(i,ii,iii))   (Probable Decline)   [restricted to river; naturally rare]
Arcoona Plateau (GAW04)Gawler
 Vulnerable   (IUCN: VU D1+2)
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 Duma]
Name derivation:
Duma from Latin meaning thorny; referring to the genus thorn-like branch tips. Horrida from the Latin 'horridus' meaning rough, shaggy, prickly; referring to its more irregular and rough appearance than the other species.
Distribution:
Found along the Murray River in South Australia, growing on floodplains and beside dry inland lakes. Also found in New South Wales and Victoria.
Status:
Native. Rare in South Australia. Rare in Victoria.
Plant description:
Stiff, divaricately branched, but rather open shrub to 1 m high and wide with greyish-brown stems, partly leafless and often with spine-tipped. Leaves crowded on very short lateral branches, eventually shed, linear, to 50 mm long and 2 mm wide, papery. Inflorescence in axillary or nodal clusters with small, green or yellowish flowers. Flowering between March and October.
Fruit type:
Green-brown angular-tuberculate 4-sided fruit.
Seed type:
Shiny dark brown to black ellipsoid to ovoid seed to 2.5 mm long and 2 mm wide.
Embryo type:
Peripheral.
Seed collecting:
Collect ripping fruits that are turning brown and containing a hard brown to black seed. Mature fruits will come off easily.
Seed cleaning:
Place fruits in a tray and leave to dry for 1-2 weeks. Then rub the fruit with a rubber bung to dislodge the seeds. use a sieve to separate unwanted material. Then 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 germination:
This species has intermediate to deep physiological dormancy.
Germination table:
DateResultT0T50Pre-treatment | Germination medium | Incubator: Photoperiod / Thermoperiod
June 201396%24d24d Fruit removed and leaching seeds in 400mg/L Gibberellic Acid for 3 days
70mm glass petri dishes on 1% w/v agar
Incubated under spring/autumn conditions
June 201332%14dNA Fruit removed
70mm glass petri dishes on 1% w/v agar
Incubated under spring/autumn conditions
June 20134%24dNA Leaching seeds in RO water for 3 days
70mm glass petri dishes on 1% w/v agar
Incubated under spring/autumn conditions
June 20130%NANA None
70mm glass petri dishes on 1% w/v 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)