Santalum acuminatum

Desert Quandong
Detail of sketch, Olive Pink (1930)
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Santalales
Family:	Santalaceae
Genus:	Santalum
Species:	S. acuminatum
Binomial name
Santalum acuminatum A.DC.

Santalum acuminatum, the Desert Quandong, is an Australian plant in the Sandalwood family, Santalaceae. Variously known as quandong, sweet quandong, or native peach, it is widely dispersed throughout the central deserts and southern areas of Australia. The use of the fruit as a flavouring, one of the best known bushfoods, has led to the domestication of the species.

Description

Santalum acuminatum grows as an tall shrub, or small tree, rarely exceeding 7 metres in height. Roots are adapted to a hemi-parasitic mechanism, utilising a haustorium, able to reach out 10 metres to other root systems.

The slender to ovate leaves are pointed at the tip, are pale or yellow-green, and leathery. These are supported on a short leaf stem, 5 - 10 mm long, the leaves themselves being 45 - 115 mm long. They are tapered in outline, and arranged in opposite pairs on the branchlets.

Flowers can be green or white on the outer parts, reddish or brown on the inner faces, these appear on stems, are just 2 - 3 mm across, and are fragrant. Fruit is produced after four years and is red or sometimes yellow, measuring 20 and 25 mm across. A 3 mm layer of flesh covers a brain-like nut with a hard shell that encases the seed. This fruit is referred to as a drupe, it ripens from green to a shiny red in late spring or summer, and is globe shaped and 20 - 40 mm across. The skin of the fruit is waxy.

Taxonomy and naming

The species was first described by Robert Brown, named in Prodromus Florae Novae Hollandiae (1810) as Fusanus acuminatus; based on his type collection made at Fowlers Bay, South Australia, in 1802. Brown gave the latin epithet acuminatus to denote the leaves - sharpened or pointed. The botanist Alphonse Pyrame de Candolle gave the current name in 1857, placing it in the genus Santalum; the genus containing Australian Sandalwood, Santalum spicatum, and White Sandalwood, Santalum album.

Several botanical names have been deemed to be synonymous with Santalum acuminatum, as described in Flora of Australia (1984) and the Australian Plant Census (2006): Santalum preissii F.Muell. in Fragmenta Phytographiae Australiae (1861); Santalum cognatum and Santalum preissianum of Miquel (1845); and Santalum densiflorum Gand. (1919).

Mida acuminata was given by Kuntze in an attempted revision, as with Eucarya acuminata (R.Br.) Sprague & Summerh..

A number of cultivars have been developed from the trials of Brian Powell at Quorn, South Australia, two of which have names protected by Plant Variety Rights Legislation. The first named cultivar of the species was named Powell’s # 1, the second is known as Powell’s Red Supreme. Two names are published in the Plant Varieties Journal: ‘Powell’s Red Supreme’ and ‘Saltbush Lane’

The plant was known to many different indigenous language groups, and is therefore known by many different names. The Wiradjuri people of New South Wales used the name guwandhang, from which the name quandong was adapted. Other indigenous names include; gutchu (Wotjobaluk, Western Victoria); wanjanu or mangata (Pitjantjatjara, Uluru), and goorti (Narungga).

Distribution

Santalum acuminatum is widely distributed throughout most southern regions of mainland Australia, including the arid centre of the country, and in some regions is common. The sandalwood cogenor, Santalum spicatum, was once more populous than this species; commercial exploitation has reversed this position.

The plant occurs in Western Australia's north to Carnarvon, reaching inland from the coastal plains, and is found throughout Southwest Australia. The number of recorded specimens in this region is low, and mainly restricted to coastal sandplains, its range having been impacted by altered land-use in the wheatbelt. Some populations are discontinuous in the distribution range, as with many species of the region, beyond the dispersal range of the seeds. Remote groups of the species are remnant to former distribution ranges, to different climates, and these may be isolated by hundreds of kilometres. The species is one of those in the region to include 'wet outliers', small populations outside of the usual low rainfall habitat.

Occurrence of the plant is also recorded in South Australia, Victoria, and New South Wales.

Ecology

The plant is hemi-parasitic; able to photosynthesize, but using the root system of other plants to acquire nutrients other than sugars. The Santalum genus of plants attaches to other species, in a non-destructive way, sustaining itself by their provision of nitrogen, shade, and water. The roots of the species have pad-like adaptations, that nearly encircle the host's root, this is typical of this genus of sandalwoods. Hosts can be other trees, or grasses, usually several plants are utilised. The taxa recorded in this relationship are species of genera; Acacia, Maireana, and Atriplex.

The tree occupies a diverse and widespread range of habitat, including creek beds, granite, gravel plains and sandy dunes. It is tolerant of drought, salt and high temperatures, and need not have a nutrient rich environ. The seedling can become established in the shade of its host, reaching for full sun once developed, so the plant is usually intermingled with host and other species.

The environs of the distribution range are subject to frequent bushfires, this requires the plant to regenerate from its roots, so the species is rarely found as an advanced tree.Those specimens exposed to bushfire and soil disturbance will occur as sprawling multi-stemmed shrubs. The plant's regrowth from the root system gives this species a lead over shrubs that recur from seed. Trees with a single main stem are in locations remote from these factors. The habit of older trees may overwhelm the adjacent plants; by monopolising the sunlight and parasitising roots of plants beyond its own canopy.

The foliage, being much paler than other trees and shrubs, makes the plant conspicuous in bushland and scrub. An occurrence of an unmolested specimen is recorded at Woodman Point in Western Australia, an area remote from the high intensity fires of altered regimes.

Emus will eat the fruit, it forming an important part of their diet, the nut remains undigested in their droppings. This is the usual method of S. acuminatum seed dispersal, when it is within the Emu's range.

A number of species interact with this plant, in a number of complex relationships, a noted example being Paraepermenia santaliella; the Quandong Moth of the Epermeniidae family. Other creatures, such as larvae of Nitidulid beetles and the Wood white butterfly, also feed on Santalum acuminatum.

Cultivation

A Desert Quandong nut sitting on a piece of paperbark.

The fruit and nut was an important food source, to the peoples of arid and semi-arid central Australia, especially for its high vitamin C content. It is commercially grown and marketed as a bush food and is sometimes made into a jam, an enterprise begun in the 1970s. It is well known as an exotic food.

Propagation and pests

The inadequate knowledge of the plant ecology led to many early failures, provision of the particular conditions of its endemic habitat is required, well drained soil and appropriate hosts increases viability. The seed has been more successfully germinated, up to 35% when it laid aside for 12 - 18 months, but cultivation of this plant has faced a number of obstacles. The species is susceptible to a number of pests and fungal disease.

The research and development of domestication of the species was first under taken by Brian Powell, at a property in Quorn, South Australia. The successful plants in this trial are classed as 'Significant Trees' by the state's National Trust. This venture came to be supported by the CSIRO, in the 1970s, eventually becoming part of the research body's 'Sustainable Ecosystems' division.

The development of horticultural practice for the establishment of commercial orchards is being researched by a number of projects.

Diseases

Soil borne agents of disease, such as Phytopthera and Pythium fungal species, may be present where the plant's preference for well drained soil is not provided. Nurseries have found the plant to be responsive to the treatments prescribed, if its presence is suspected, such as Phosphorous acid soil applications. A climate of high heat and humidity has occasionally induced black spot on the leaves.

Harvest

The fruit and nut of S. acuminatum are collected from the tree, or the nut from a dropping of the emu; wild harvest remains as the primary source for the widely used fruit.. This was the method adopted by the colonists after their introduction to it. The establishment of experimental plantations, by the CSIRO in the 1970s, has seen a steady increase in supply by orchards to the market.

Uses

Food

The commercial use of the fruit includes its addition to sweet and savoury foods, the flavour is tart and reminiscent of peach, apricot or rhubarb. In South Australia S. acuminatum is called "Wild Peach" or "desert Peach". The fruit and nut of the plant were featured in a bushfood series of stamps produced by Australia Post.

The fruit has been made commercially available, the distinctive flavour is used as an additive, particularly as a uniquely australian product. This has usually been sourced from wild trees, sometimes by Aboriginal corporations, although the viability of commercial orchards is also being trialled. Many Aboriginal peoples are known to have used the fruit, but mainly they gathered the nuts. The undigested nut can be easily gathered from emu droppings.

The kernel has been identified, analysed, and monitored, as a 'wild harvested Australian indigenous food', by Food Standards Australia New Zealand. The product is found to very high in fats, over half by weight, and cites its use by indigenous Australians.

Medicine

The fruit, containing vitamin C, and the kernel of the nut, containing complex oils, were used by the peoples in whose countries the species occurred. Antibacterial qualities are present in the wood of this, and all the Santalum spp., especially in the roots. A known application of the extract was to heal ailments of the skin. The commercial production of cogenor Santalum spicatum is more advanced than this species, although research is being undertaken into the marketing of these medicinal substances.

Fuel

The seed is very high in flammable oils, like a candlenut, so it is able to be burnt as an illuminant. The wood is also oily, useful for starting a fire as a friction stick.

Timber

The hard, oily, timber is used for furniture and cabinet making. It is a durable material, but lacks the aromatic qualities of sandalwoods. The hard and wrinkled nuts have been used ornamentally, for necklaces and shirt buttons, and were used as marbles on chinese checkers' boards.

History

The oil of sandalwoods, primarily Santalum album, was described and investigated by pharmacologists, this species gained similar attention upon discovery. The more widely known Australian sandalwood, S. spicatum, was extensively harvested and exported, leaving S. acuminatum as the more common Santalum in many regions.

The established use of the fruit, by aboriginal peoples, was acknowledged by the early settlers of the colonies; this product was made into jam and chutney. The fruit is most frequently mentioned, in texts such as Flowers and plants of Western Australia, and to be traded as a commodity, however, the kernel of the seed has, historically, been the most extensively used.

References

External links

Media related to Santalum acuminatum at Wikimedia Commons

• Quorn Quandongs

• The Desert Quandong
• Australian Quandong Industry Association
• The Quandong Story