Plants of
South Australia
Swainsona laxa
Fabaceae
Yellow Skeleton Swainson-Pea
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Botanical art

Kath Alcock paintings: 2

Prior names

Swainsona laxa var. rigida

Swainsona rigida

Etymology

Swainsona named after Isaac Swainson (1746-1812), an English scientist and horticulturalist who had a private botanic garden near London. Laxa from the Latin 'laxus' meaning loose or open.

Distribution and status

Found scattered in the north-eastern corner of South Australia in sandy soil especially on the upper slopes of sand-ridges. Also found in Northern Territory, Queensland and New South Wales. Native. Common in South Australia. Uncommon in New South Wales. Common in other states.
Herbarium region: Lake Eyre
NRM region: South Australian Arid Lands
AVH map: SA distribution map (external link)

Plant description

Shrub-like herb to 2 m high. Leaves to 17 cm long with 11-19 leaflets; leaflets obovate or narrow-obovate to 27 mm long and 15 mm wide. Flowers racemes to 30 cm long with 15-20 yellow pea-flowers. Fruits are pale brown, thin papery pod to 25 mm long and 15 mm wide. Seeds are yellow brown reinform seed to 5 mm long and 3 mm wide with a smooth surface. Seed embryo type is bent.

Seed collection and propagation

Collect seeds between October and November. Collect mature pods, those that are drying off and contain hard seeds. Mature pods can be found lying on the ground next to the plant. Place the pods in a tray and leave to dry for a week. When dried the pods become hard and difficult to open. 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. From one collection, the seed viability was high, at 95%. This species has physical dormancy that need to be overcome for the seed to germinate (e.g. nicking or softening the seed coat).

Seeds stored:
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LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
BGA 
MSB
3,100 (32.28 g)
3,100 (32.28 g)
20+22-Oct-2007DJD912
Lake Eyre
19-Sep-200895%-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.