Sturt's desert pea, Swainsona formosa, is the state flower of South Australia. It was adopted as the state's floral emblem in 1961.
First discovered by the English explorer William Dampier on his 1688 visit to islands off the northwestern Australian coast, the plant's presence was noted by Australian explorer Charles Sturt in 1844 in areas between Adelaide and Central Australia. The flower was named after Sturt to commemorate his exploration of inland Australia.
Sturt's desert pea was formerly called Clianthus formosus and is also known as Willdampia formosa (named after Dampier). The specific name formosa is Latin for "beautiful."
Sturt's desert pea is a slow-growing, creeping plant with stems and leaves appearing soft grey due to a covering of fine hairs. The flowers stand upright on fleshy stalks, up to 30 centimetres tall. The large pea flower can be in various shades of red, with a base of deep red to purple to black.
The genus name Swainsona honors English botanist Isaac Swainson who maintained a private botanic garden near London in the late 18th century. The former name, Clianthus, is now thought to be confined to New Zealand.
Sturt's desert pea can be found in arid woodlands and on open plains, often as an ephemeral following heavy rain. It is able to withstand temperature extremes in inland deserts, and light frosts are tolerated by established plants.
A protected species in South Australia, Sturt's desert pea flowers and plants must not be collected on private land without the written consent of the owner. Collection on Crown land is illegal without a permit.