Queensland's Department of Primary Industry is investigating the food potential - and ultimately the commercial value - of nuts on two rainforest trees found along the State's coastline. The nuts from the trees Athertonia diversifolia and Elaeocarpus bancroftii have always been valued as food items by Aboriginals.
Mr. Tony Irvine*, of the CSIRO's Tropical Forest Research Centre, Atherton, has supplied seeds for trial plantings. Mr. Irvine has already made preliminary observations on growth, flowering and fruiting biology of the trees as a basis for considerations on commercial development.
Athertonia diversifolia is found only in the rainforests of the Atherton Tablelands area and is adaptable to planting in the open. Mr. Irvine suggests that apart from some limitations due to frost it could do quite well in coastal southern Queensland and northern New South Wales, where the climate is similar to that of its natural range.
Although mature fruit crops in both natural and planted situations seem to be sparse, this could be corrected by increased nutrition and light. The taste of Athertonia is very acceptable - they seem crisper and less oily than macadamia nuts, suggesting that the fat content is less. There is currently no information on the nut's fat, protein and carbohydrate content, or on its storage and processing qualities. While much more work is needed to understand and utilise the tree's fruit, the tree itself could also have a bright future in the nursery trade as an ornamental because of its attractive foliage and form. It is seldom large enough to be commercially milled for timber.
Eleaocarpus bancroftii is found mostly in the rainforests of the coastal lowlands between Tully and the Bloomfield River area and mature fruit crops can be quite heavy on individual trees in natural situations.
The drupes of the Elaeocarpus bancroftii are fleshy and blue-green. Mr. K.W. James (OIC, Food Science, Armed Forces Food Science Establishment, Tasmania) has obtained 2.3 per cent protein and 1.1 per cent fat in an analysis of the seed of Eleaocarpus bancroftii. Its storage and processing qualities, however, are unknown.
Current economic criteria suggest that there are no commercial possibilities for these two rainforest trees as food sources, but in the long term mankind needs as many potential food sources as possible. Existing commercial considerations should not necessarily prevent research on such resources. The world's main horticultural crops have been transformed over the centuries, or even millennia, from ancestral stocks, which in many cases, bear little resemblance to modern productive cultivars.
As tropical rainforest is so rich in plant species, it is not surprising that among them are some that could be developed as food plants. (This is in addition to the valuable timbers and other products, such as rubber, that come from the world's stock of rainforest trees.)
Several popular fruits (like bananas) and nuts (such as the Brazil nut) are derived from tropical forest plants that have undergone selection for the traits we find desirable - usually increased size and palatability. Obviously the products of 'new' plants found in the forest may also benefit from some selection to enhance their potential, but before deciding on improvements we face the problem of identifying what is edible in the first place.
In Australia we are lucky: the Aborigines have identified many edible plants - for example, the kernels of two Queensland tropical rainforest trees. Mr. Tony Irvine, of the Atherton Centre, has investigated the food potential of these plants.
The result is the re-discovery of two very pleasant types of nut - the Atherton nut, or 'black-and-tans', from the tree Athertonia diversifolia, and the Kuranda quandong (not related to the quandong fruit of the inland) from Elaeocarpus bancroftii. The nuts must be removed from within their fleshy fruits, and can be eaten fresh, or dried and then kept.
Mr. Irvine's travels in the forest and knowledge of Aboriginal lore have enabled him also to identify scientifically some edible fruits with unusual flavours. The lemon aspen, Acronychia acidula, for example, is a small white fruit with a very refreshing taste. We can eat it raw, although some may consider it a little sharp, and it certainly makes excellent marmalade. Also tart, the native tamarind (Diploglottis australis) has an orange flesh and is rather more acid; however, it has a flavour that, when sweetened a little, would go well in a cordial.
By contrast, Buchanania arborescens, which has no common name, is a tree that produces sweet, black, stone-bearing fruits. It belongs to the same plant family as cashews and mangoes. Another sweet fruit, tasting similar to a cherry, comes from Eugenia reinwardtiana.
Figs are well-known and popular - and we have several species of fig tree, one of which produces edible sweet brown fruit two or three times a year. The tree's botanical name is Ficus copiosa, which means literally 'plentiful fig'.
To close the list of those native rainforest food plants we currently know of, we should include the Davidsonian plum (Davidsonia pruriens var. jerseyana), a large, garishly-coloured fruit with a blue skin and bright red flesh. Before eating this one you need to remove the irritating hairs on the skin. It is decidedly acidic and you may prefer to use it for jam or wine, as the early European settlers did.
(Having tried some of the above fruits and nuts in the course of his research for this article, your Ecos correspondent can personally recommend them.)
Now, recognising what's good to eat in the forest is still a long way from commercial production of marketable fruits. Horticulturists would need to invest a lot of money in investigating the flowering and fruiting biology of the plants and the factors that affect their yield, and in selective breeding of them.
The Queensland Department of Primary Industries is currently interested in the two edible nuts, but recognises the problems involved in placing a new product on the market. Macadamia nuts, from a tree native to southern Queensland and northern New South Wales, required many years of developmental work before they became a commercial proposition. Sadly, most of this occurred in Hawaii, following the collection of macadamia seeds by Americans who recognised their potential earlier this century. Although Australia is now producing them, many of the world's macadamias still come from Hawaii! Let's hope Australia won't miss out again.
Athertonia has some advantages over macadamia trees. The fruit ripens more evenly and the shell cleaves into two halves, which may make it easier to remove. And Athertonia could be used for more than just its nuts: the tree itself has attractive foliage and form, which may make it popular as an ornamental, and the flowers attract the domestic honey bee.
In his research, Mr. Irvine has, unfortunately, not gone personally unscathed. On one occasion he became very sick after eating less than ½ gram of a fruit that he was investigating. The occasional accident such as this is more or less unavoidable if you really want to discover new sources of food. The rest of us are lucky we needn't worry about poisoning every time we bite into an apple or banana, thanks to brave people like Mr. Irvine who, thousands of years ago, demonstrated the safety of what have become the common fruits of today.
Commercial prospects for edible nuts of Athertonia diversifolia (C. T. White) L. Johnson and Briggs (Proteaceae), and Elaeocarpus bancroftii F Muell and F. M. Bailey (Elaeocarpaceae), A. K. Irvine. In "The Food Potential of Seeds from Australian Native Plants'. Proceedings of Colloquium, Deakin University 7 March, 1984, 1985, 174-89.
* PLANT ENTHUSIAST
Tony Irvine is an out-and-out plant enthusiast. On his three-hectare property right on the Atherton Tablelands, Mr. Irvine has planted more than 800 different rainforest plants. "It's a special area of interest for me", he said. "I'm especially interested in North Queensland native species and I'm trying to grow as many as possible."
The property has an eucalyptus belt, mainly of North Queensland species, an extensive fruit garden, in addition to other plants and foliage. Mr. Irvine said he also had a good collection of palms. "These are very popular in the tropics and I'm putting together some facts and figures on specific characteristics."
DATE: January 1989
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