According to Plants of the World Online, Gymnostoma sumatranum is endemic to the island of Sumatra in Indonesia.[2] The IUCN Red List indicates a wider range for the species, including Sumatra, Java, Peninsular Malaysia, Borneo, the Philippines, Sulawesi, Maluku, New Guinea, the Bismark Archipelago, and the Solomon Islands.[1]
It grows in a range of habitats, including primary lowland, hill, and montane forests. It has been found on thin soil over limestone outcrops, in heath forests on poor sandy soils, and at the edges of river and swamp forests. It has also been found in Dacrydium–Tristania–Podocarpus forest and montane forests dominated by trees of the beech family (Fagaceae).[1]
In Malaysia, G. sumatranum is known as Rhu Bukit — with bukit in Malaysian meaning "hill". The other common she-oak species in Malaysia is Casuarina equisetifolia known as Rhu laut - laut in Malaysian means "sea" and typically it grows along the seashore on sandy substrates. In Sarawak it is a protected species (5). G. sumatranum typically grows further inland. However, when occurring in coastal regions, it provides good indication that the soil is dry and out of the littoral and inundation zone since G. sumatranum will not normally tolerate sandy or boggy soil.
