Clonostylis is a monotypic genus of flowering plant in the family Euphorbiaceae.

The sole species is Clonostylis forbesii is a flowering tree found in Sumatra.

It has small glabrous leaves with an elliptic shape, arranged spirally.

Since only one specimen has been found, according to the Nationaal Herbarium Nederland, and it did not exhibit fruit or staminate flowers, a more definite classification is not yet possible.

(The species is unisexual, and the specimen in question had only pistillate flowers.