Queensland State Archives posted a photo:
Plectronia is a genus of flowering plants belonging to the Rubiaceae family, and includes only one species: Plectronia parvifolia.
It is a plant from Burma and Malaysia. The leaves of this thorny bush are largely consumed by the natives in their curries. The pulp is attached to the seeds and eaten by the natives, but for the European taste, it is not very pleasant. In India the fruit is eaten by the Indians, and the leaves are also used as food and for the curries as a seasoning.
Description source: Wikipedia
Image source: Queensland State Archives, Digital Image ID 22449