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Elaeocarpus angustifolius Blume 1827
pronounced: el-lee-oh-KAR-puss an-guss-tee-FOH-lee-uss
(Elaeocarpaceae – the quandong family)
synonym: Elaeocarpus grandis F.Muell. 1860
pronounced: el-lee-oh-KAR-puss GRAN-diss
common names: Blue Quandong, Blue Marble Tree
Elæocarpus is derived from the Latin elæa which in turn comes from the Greek ελαια (elaia), the olive, and καρπος (karpos), fruit; angustifolius is from the Latin angustus, narrow, and folium, a leaf .
This is an Australian native, occurring in the Northern Territory, on Cape York Peninsula, in north-east Queensland, and as far south as north-eastern NSW, at an altitudinal range from near sea level to about 1000 m. It is usually found in well-developed rainforest, where it is favoured by disturbance. It is quite a fast-growing tree, flowering and fruiting profusely. The tree also grows in New Guinea. After disturbance, the tree can grow extraordinarily quickly to large dimensions (up to 50 m tall). This has led to greatly exaggerated and unfounded claims as to its suitability as a plantation tree.
Buttresses are normally conspicuous on the trunk, even on small trees. The branches are generally in whorls, particularly on small trees. The crown of the tree is thin, as the leaves occur only on the extremities of the branches.
The leaf blades, slightly serrated, are approximately 8-15 cm long by 2.5-4.5 cm wide, gradually narrowed into the petiole, which lacks a pulvinus. Foveoles occur not only in the forks of the lateral veins, but also in the forks where the lateral veins branch. Before they fall from the tree, the leaves turn orangy red – there are a scattering of such leaves on the tree at most times.
Masses of frilly while flowers are produced in autumn; each flower has sepals less than 14 mm in length, and petals that are divided at the apex into 4 or 5 lobes up to 5 mm long. There are approximately 50 stamens, and the ovary is hairy.
The fruits are a brilliant, iridescent blue, globular, up to 2 cm across, with the endocarp deeply pitted, with 5-7 sutures. Inside the fruit is a highly ornamental stone that has been used to make jewellery. The remains of the hard pitted seed coats can usually be found on the ground underneath mature trees. The fruits are eaten whole by cassowaries, wampoo pigeons and spectacled flying foxes, who pass the seeds undamaged
The fruit is edible for humans, but is sour to taste in raw form. It can be used in jams and pies, or puréed. Aboriginal peoples were known to make up a paste of the ripe fruit by squashing them into a bark trough filled with water.
The timber is soft and lightweight, very suitable for carving and for cooperage.
The fruit coloration is produced not by anthocyanin pigments, as is the case with most other blue fruits. It comes from a structural interference common in insects and birds, but rare in plants. In the epidermal cells of the fruit, cellulose layers form a special structure outside the cell membrane but inside the cell wall, and create a thin-film interference with blue light, and this reflects the blue colour. The phenomenon is discussed by the American scientist D.W. Lee in Iridescent Blue Plants (1997).
Photographs ©taken in Picnic Bay 2016
Page last updated 3rd January 2018