Seeds of South Australia
Swainsona unifoliolata (Leguminosae)
Gypsum Swainson-pea
List of species for Swainsona
Display more images
Click on an image to enlarge it
Seed collecting:
September to November
Herbarium region:
North Western
NRM region:
Alinytjara Wilurara
IBRA regions
Maralinga (GVD03)Great Victoria Desert
 Rare   (IUCN: RA d(ii))
Tallaringa (GVD05) 
 Rare   (IUCN: RA d(ii))
Breakaways (STP01)Stony Plains
 Vulnerable   (IUCN: VU D2)   [restricted habitat]
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 Swainsona]
Name derivation:
Swainsona named after Isaac Swainson (1746-1812), an English scientist and horticulturalist who had a private botanic garden near London. Unifoliolata meaning with one-leaflet.
Distribution:
Found scattered in a small area in the west central corner of South Australia on margins of salt lakes on gypsum and limestone. Also found in Western Australia and Northern territory.
Status:
Native. Rare in South Australia. Common in the other states.
Plant description:
An erect or ascending perennial herb to 30 cm high, with several branched stems from a taproot. Leaves to 7 cm long with one leaflet or occasionally 3 leaflets, with the unifoliolata leaves on the lower part of the branches, leaflets mostly obovate to 26 mm long and 15 mm wide and when more than one, the terminal much larger than the lateral. Flower raceme to 12 cm long of dissimilar age with purple pea-flowers. Flowering between August and September.
Fruit type:
Black, narrow elliptic, inflated and curved pod to 25 mm long and 4 mm wide.
Seed type:
Brown mottled, semi-flat reniform seeds to 2 mm long and 1 mm wide with a wrinkled surface.
Embryo type:
Bent.
Seed collecting:
Collect mature pods, those that are drying off and contain hard seed. Mature pods can be found lying on the ground next to the plant.
Seed cleaning:
Place the pods in a tray and leave to dry for 1-2 weeks. Use a rubber bung to rub the pods or break the pods open with your fingers to dislodge the seeds. Use a sieve to separate the 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 high, at 90%.
Seed germination:
This species has physical dormancy that needs to be overcome for the seed to germinate (e.g. nicking or softening the seed coat).
Germination table:
DateResultT0T50Pre-treatment | Germination medium | Incubator: Photoperiod / Thermoperiod
Jul-15100%7 d7 d seed coat nicked with scalpel;
1% agar;
Incubated under spring/autumn conditions
Jul-1528%7 dNA
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)