The islands of Wallacea are home to a mix of plants and animals from both terrestrial realms, and have many unique species that evolved in isolation.

Borneo and the other Indonesian islands west of Sulawesi are part of Sundaland, and were connected to the Asian continent when sea levels were lower during the ice ages.

In the mid-montane forests (1500-2000 meters elevation) Fagaceae, especially Lithocarpus menadoensis and L. celebicus, Myrtaceae, and Agathis are predominant.

[6] Upper montane forests are characterized by conifers, including species of Agathis, Podocarpus, Dacrycarpus, Dacrydium, and Phyllocladus, together with Myrtaceae and the shrubs Rhododendron, Vaccinium, Gaultheria, and Tasmannia piperita.

Herbs include the daisy Keysseria, the ginger Alpinia, Potentilla leuconata and P. parvus, and the grasses Poa and Agrostis.

The Celebes warty pig lives in the lower montane and lowland rain forests of Sulawesi and other islands of Wallacea.

The endemic Mountain anoa (Bubalus quarlesi) is a dwarf buffalo which stands only 70 cm (28 in) high.