Cossinia is a genus of four species of rainforest trees, constituting part of the plant family Sapindaceae. The genus has a disjunct distribution, occurring in Mascarene Islands, Australia, New Caledonia and Fiji.
They grow naturally in rainforests, including seasonally drought–prone rainforests, and associated non–fire–adapted vegetation types.
Cossinia trifoliata trees, endemic to New Caledonia, have become vulnerable to global extinction according to the International Union for Conservation of Nature (IUCN)'s 1998 assessment.
Cossinia australiana trees, endemic to restricted habitat areas of central-eastern and southeastern Queensland, Australia, have the official national and Queensland state governments' "endangered" conservation status. Within their known endemic region the trees grow naturally in habitats which have historically had their native vegetation extensively destroyed and have been further threatened.
The genus was first described in 1786 by Jean-Baptiste Lamarck in Encyclopédie Méthodique: Botanique. The publication includes descriptions of the species Cossinia pinnata and C. triphylla, named earlier by Philibert Commerson.
In 1982 Australian botanist Sally T. Reynolds formally described the new species name Cossinia australiana, recognised that C. triphylla is a synonym of C. pinnata and updated Ludwig A. T. Radlkofer's species identification key to include all four currently accepted species.