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Australian Floral Emblems - Swainsona formosa

Paul Nixon

Sturt's Desert Pea (named after the early explorer, Charles Sturt) is the common name of the floral emblem for South Australia, The 'Classic' Desert Pea flower is a deep scarlet or red on the standard, keel and wings with a black or dark red boss. In nature many colour variations are known, ranging from red through pinks to yellow and even albino forms. The boss is generally black or shades of dark red to brown.

The spectacular flowers of Sturt's Desert Pea are around 80 mm long. The large, rounded "boss" in the middle of the flower may be black or reddish, as shown here. Select the thumbnail image or plant name for a higher resolution image (43k)

These spectacular flowers were first collected by a colourful character, William Dampier, pirate and adventurer in what is known as Dampier Archipelago, in August/September 1699. His collection of 23 specimens is housed in the Sherardian Herbarium at Oxford and is of major historical interest in that it represents the first recorded collection of Australian plants. The accepted scientific name is Clianthus formosus (now changed - see footnote).

In cultivation the desert pea is regarded as difficult and few people attempt to grow it. It is treated as an annual although it is, to some extent, a perennial. However, if the soil is deep and well drained in a sunny and, in particular, a protected position, it will have few problems.

Germination of Sturt's Desert Pea Seed Is Easy

Seed is widely available. There are about 150 small kidney shaped seeds in one gram but small quantities are available in packets. In early spring, prepare the pot in which you want to grow the plant to maturity. A 10 litre size pot or hanging basket will be ideal. The potting mixture should be equal parts of sand, loam and peat. Before sowing the seed where it is to grow, it should be nicked in the back of the seed coat with a knife to break nature's long-lasting protective layer. Place several seeds, widely placed, close to the surface and drench the pot with a litre of general purpose fungicide. Seedlings should emerge in a few days. The young seedling's root system is growing so fast at this stage that transplanting would be a problem. One centimetre of shoot may have 10 centimetres of root.

Swainsona formosa is its natural habitat at Arkaroola in the northern Flinders Ranges of South Australia. Select the thumbnail image or plant name for a higher resolution image (59k).

Growing On Sturt's Pea Plants

Place the pot in a raised sunny position. In winter where frost can be expected, the morning sun should be kept off the plant. The western side of a building would be suitable. Desert Pea should be protected from slugs and snails. During summer, Red Spider may be a problem. This is indicated by a mottled brownish look especially on the leaf underside. These should be sprayed with an insecticide. Fertilise with complete slow-release fertiliser at half recommended rate in spring and autumn. When the tendrils get too long and ungainly they should be pruned back.

Notes on botanical terms:

  • Boss - a rounded protusion at the base of the standard on Swainsona formosa
  • formosa - from latin formosus = "beautiful"
  • Keel - in a "pea" flower, the two fused petals enclosing the stamens
  • Standard - the large upper petal of a "pea" flower
  • Swainsona - after Isaac Swainson, a scientist and plant collector)
  • Wings - petals at either side of the keel

Reprinted from the June 1988 issue of the Society's journal "Australian Plants". Note that the botanical name has changed to Swainsona formosa during the intervening years.

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