Kewa acida is one of the eight species currently recognized in the genus Kewa, the sole genus in the family Kewaceae. It is a bushy grey-leaved annual or short-lived perennial plant, with white flowers, endemic to St Helena, where it has been called the "salad plant". It is regarded as Critically Endangered. The succulent leaves are high in Vitamin C and were used by sailors in the past as a scurvy preventative.