Xanthosia rotundifolia is a species of the plant family Mackinlayaceae, but sometimes also placed in Araliaceae or Apiaceae. The informal name of this species, Southern Cross, is derived from the common name of the constellation Crux. The flowers, white in colour, symmetrical, and cruciform in outline, are reminiscent of the distinctive southern stars. Its habit is as a shrub between 0.35 metres (1.1 ft) to 0.8 metres (2.6 ft) in height. It only occurs in southern regions of Southwest Australia, in a variety of soils over granite or laterite. It was first described by de Candolle in 1829.