Swainsona colutoides, commonly known as bladder senna or bladder vetch,[1] is a species of flowering plant in the family Fabaceae and is endemic to arid areas of Australia. It is an erect annual, shrub-like herb, with imparipinnate leaves usually with up to 13 to 17 egg-shaped leaflets with the narrower end towards the base, and racemes of 10 to 20 purple flowers.
Swainsona colutoides is an annual, shrub-like herb, that typically grows to a height of and has glabrous stems. Its leaves are imparipinnate, mostly long on a short petiole with 13 to 17 egg-shaped leaflets with the narrower end towards the base, long and wide. There are stipules often more than long at the base of the petiole. The flowers are arranged in racemes of 10 to 20 on a peduncle up to long, each flower long on a pedicel long. The sepals are long and joined at the base to from a bell-shaped tube, the sepal lobes shorter than the tube. The petals are purple, the standard petal long and up to wide, the wings long, and the keel long. Flowering mainly occurs from August to December, and the fruit is a crescent-moon shaped pod long and wide with the remains of the style about long.[2] [3]
Swainsona colutoides was first formally described in 1876 by Ferdinand von Mueller in his Fragmenta Phytographiae Australiae.[4] [5] The specific epithet (colutoides) means "Colutea-like".[6]
This species of pea grows in sandy and clayey soils in Western Australia, the Northern Territory, South Australia and New South Wales. It occurs in the Avon Wheatbelt, Coolgardie, Great Victoria Desert, Mallee and Murchison of Western Australia, the Nullarbor Plain, Great Victoria Desert, Eyre Peninsula and Murray Darling Depression bioregions of South Australia, the MacDonnell Ranges in the Northern Territory and the far south-west of New South Wales.[7]
An erect annual or biennial, its high production of larger seeds, delayed dehiscence, and low concentrations of the toxin swainsonine gives it potential for development as a forage crop.[8]