Sphaerophysa salsula is a species of flowering plant in the legume family known by the common names alkali swainsonpea,[2] Austrian peaweed, and red bladder-vetch.

It is native to Asia but it is known in many other parts of the world as an introduced species and often a noxious weed.

It grows in cultivated land and disturbed habitat, easily tolerating alkaline substrates.

It is inflated and bladderlike, hairless, translucent, shiny, and papery when dry.

These include the bacterium Paracoccus sphaerophysae, which was recently isolated from the roots of this species, and named for it.