This genus is often described as cosmopolitan, meaning it has worldwide distribution. The botanist Ludwig Diels, author of the only monograph of the family to date, called this description an "arrant misjudgment of this genus' highly unusual distributional circumstances ("arge Verkennung ihrer höchst eigentümlichen Verbreitungsverhältnisse")", while admitting sundew species do "occupy a significant part of the Earth's surface ("einen beträchtlichen Teil der Erdoberfläche besetzt")". He particularly pointed to the absence of "Drosera" species from almost all arid climate zones, countless rainforests, the American Pacific Coast, Polynesia, the Mediterranean region, and North Africa, as well as the scarcity of species diversity in temperate zones, such as Europe and North America.