Cleistanthus is a plant genus of the family Phyllanthaceae, tribe Bridelieae, first described as a genus in 1848.

[3][4] It is widespread in much of the Old World Tropics in Asia, Africa, Australia, and various oceanic islands.

[2][5][6] Cleistanthus collinus is known for being toxic and may be the agent of homicides or suicides.

[7]