Plants of
South Australia
Swainsona affinis
Fabaceae
Common Poison Pea,
Small-leaf Swainson-pea
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Adelaide
Arkaroola
Ceduna
Coober Pedy
Hawker
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Keith
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Botanical art

Kath Alcock painting: 1

Prior names

Swainsona microphylla var. affinis

Swainsona microphylla ssp. pallescens

Swainsona microphylla ssp. glabrescens

Swainsona microphylla ssp. affinis

Common names

Common Poison Pea

Small-leaf Swainson-pea

Etymology

Swainsona named after Isaac Swainson (1746-1812), an English scientist and horticulturalist who had a private botanic garden near London. Affinis from Latin meaning allied, that is, relating to or similar to another species.

Distribution and status

Found scattered in the far northern part of South Australia, growing in red sandy loam, often with mulga and callitris, on margins of salt lakes, claypans, sand dunes and creeklines. Also found in Western Australia, Northern Territory, Queensland and New South Wales. Native. Common in South Australia. Common in the other states.
Herbarium regions: North Western, Lake Eyre, Gairdner-Torrens
NRM regions: Alinytjara Wilurara, South Australian Arid Lands
AVH map: SA distribution map (external link)

Plant description

A prostrate perennial herb to 25 cm high, with numerous stems arising from a taproot. Leaves very variable but mostly to 10 cm long with 7-25 leaflets, with largest at the base. Flower racemes to 30 cm long with 5-35 purple, pink, yellow or white flowers. Flowering between June and August. Fruits are broad oblong to spherical pod to 11 mm long and 7 mm wide, much inflated. Seeds are orange to brown mottle, reniform seed to 2 mm long and 1.5 mm wide, with a wrinkled surface. Seed embryo type is bent.

Seed collection and propagation

Collect seeds between September and October. Collect mature pods, those drying off with hard seeds inside. Mature pods can be found lying on the ground next to the plant. Place the pods in a tray and leave to dry fro a week. When dried the pods can 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 80%. 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:
  Hide
LocationNo. of seeds
(weight grams)
Number
of plants
Date
collected
Collection number
Collection location
Date
stored
% ViabilityStorage
temperature
 
MSB

2,000 (4.69 g)
1523-Oct-2007DJD914
Lake Eyre
95%
BGA1,200 (3.38 g)30+29-Sep-2007DJD893
Lake Eyre
19-Sep-200880%-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.