Distribution of the number of native species of Croton in the Western Indian Ocean Region. There are 123 native species overall in the region, with 114 native to Madagascar; one of them (C. adenophorus) is shared with Mayotte, and the single species in the Union of the Comoros (C. humblotii) also occurs on Mayotte. The species on Mauritius and Réunion only occur there. The map of Madagascar shows how many species occur in each of the six former provinces (there are varying levels of overlap between provinces; see text for details).