Eucalyptus patens, commonly known as yarri or blackbutt,[1] is a species of flowering plant in the family Myrtaceae and is endemic to the south-west of Western Australia.

[5][6][7] The epithet patens is Latin, meaning spreading or outspread, referring to the form of the tree "standing open", although this is not a characteristic that distinguishes the species.

It is often found in depressions, along stream banks or in valleys in the Peel, South West and Great Southern regions.

[11][12] On the Darling Plateau, yarri is found in deeper valleys with jarrah or marri above the freshwater paperbark and flooded gum, moitch, and on slopes above swamp plant communities on minor tributaries.

The roughly textured bark provides diverse habitat and refuge for insects, which are searched out by sitellas (Neosittidae) moving along the branches.

[17] In addition, even in forest where timber harvesting is allowed, informal reserves placed around streams exclude the tree, which predominantly occurs in the wetter parts of the landscape.

The air dried density of the wood is 690 to 915 kilograms per cubic metre (43 to 57 lb/cu ft) and is it suitable for construction, railway sleepers and flooring.

[19] The tree produces a large amount of pollen and flowers before marri, a major source of nectar, so this can be used to increase the beehive's brood.