Lithocarpus kalkmanii is a locally common endemic oak in the hills of Borneo between c.900-2,000 m.
In external appearance the acorn of L. kalkmanii is similar to the even larger acorn of L. turbinatus (another endemic oak) which overlaps in range on Mount Kinabalu and the two acorns are frequently confused with each other.
In general L. turbinatus is more common at higher altitudes on Kinabalu whilst, L. kalkmanii is more common at lower altitudes.
These two oaks can be distinguished by the differing appearance of the internal nut once the the pericarp (outer layer) of the acorn has been removed.
