Cucumber (Cucumis sativus) and melon (C. melo) have numerous wild relatives in Asia and Australia, and the sister species of melon is from Australia.

Among the fundamental questions regarding cultivated plants is their geographic origin and region of domestication. The genus Cucumis, which includes cucumber (Cucumis sativus) and melon (Cucumis melo), has numerous wild African species, and it has therefore been assumed that melon originated in Africa. For cucumber, this seemed less likely because wild cucumbers exist in India and a closely related species lives in the Eastern Himalayas.