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 thorn-like branch tips of the Genus . Horrida from the Latin 'horridus' meaning rough, shaggy, prickly, referring to its more irregular and rough appearance than the other species.
Found along the Murray River in South Australia growing on floodplains and beside dry inland lakes. Also found in New South Wales and Victoria.
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-tip. 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:
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
Jun-1396%24 d24 d seeds excised from fruit, 400mg/L gibberellic acid 3 d;
1% agar;
Incubated under spring/autumn conditions
Jun-1332%14 dNA seeds excised from fruit;
1% agar;
Incubated under spring/autumn conditions
Jun-134%24 dNA leached in water 3 d;
1% agar;
Incubated under spring/autumn conditions
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)