An Untapped Bounty –
It still shocks me that us Aussies are fortunate enough to have native citrus growing in this amazing country of ours and yet our fruit bowls are stacked with oranges, limes and lemons that originated in Asia, but not our indigenous fruits.
Thankfully that is beginning to change, with finger limes, in particular, starting to make a splash in the culinary world. And so they should. Also known as caviar lime, the fruit of this delicious native citrus forms in finger-shaped tubes, packed full of tiny balls of juice which burst in your mouth when you bite into them. Zesty and pretty to look at as they come in a variety of colours, beads of finger lime flesh add pop (literally) to dressings, salads and desserts and make a simple, but striking garnish to a multitude of dishes.
The fact that they are fairly easy to grow means that this native citrus is suddenly cropping up on menus all over the country as farmers begin to see the commercial value of this unique Australian plant.
And whilst finger limes are currently in the limelight, they are not are only native citrus.
Microcitrus and Eremocitrus
Although indigenous Australian peoples have been aware of their lands’ native citrus plants for generations it was the American botanist W. T. Swingle who classified them into the genera Microcitrus and Eremocitrus.
The genera Microcitrus contains seven species. Five of these native citrus species can be found in the coastal rainforest region ranging from northern New South Wales up to the Cape York Peninsula in Queensland. The remaining two species make their home across the Torres Strait in New Guinea. Interestingly, the famous finger lime (Microcitrus australasica – Gulalung in the Bundjalung language) also appears in the wet/dry monsoon woodlands near Darwin in the Northern Territory. I say interestingly, as this region of finger lime trees is a lone island, with no known connection between it and the east coast plants.
The Microcitrus and Eremocitrus species are distinguished by acidic fruits – even for citrus. Perhaps this is one reason why it’s taken a while for their culinary potential to be realised by non-indigenous Australians as for a while sweetening them with loads of sugar to make jams and chutneys seemed to be their only, rather limited, use. Luckily, we have become more imaginative in recent years (and taken a few tips from traditional owners of the land) and our native citrus are beginning to find a place on plates both here and overseas.
In addition to eating their fruit, native citrus are being looked at as rootstocks for tropical varieties of citrus trees, not just in Australia. We have a genera called Paramignya trimera (see below for more information) which grows like a woody vine. If it could be used as rootstock to create a climbing lime or mandarin, that would spark a lot of interest in gardeners from Melbourne to London.
Types of Native Citrus
Australia has three main types of native limes:
- Australian round lime
- Australian finger lime
- Australian desert lime
Microcitrus Australis – Australian Round Lime or Dooja
Also known as native lime, native orange, Gympie lime
It grows naturally in the margin of the rainforests from Beenleigh through to Gympie in south east Queensland. Generally a slender tree, if it’s out in the open it may produce multiple trunks. They have been known to reach 20m in height.
The fruit is 1-1.5 inches in diameter and is edible when green, but will ripen to yellow if left on the tree. Australian round limes are, as their suggests, usually round, though they can also be pear-shaped. They have a thick, rough skin and pale green pulp.
Microcitrus Australasica – Australian Finger Lime
Also known as caviar lime, Gulalung.
Used by indigenous Australian peoples for thousands of years both as a food and medicine – both to ward off disease and as an antiseptic, amongst other things, finger lime is currently having a moment as a gourmet bushfood.
They occur naturally from Brisbane in Queensland down to the Clarence River region in New South Wales.
This native citrus tree can grow to 10m, though it’s often found as a thorny under-storey shrub.
The fruit is quite unique and comes in a charming range of colours when ripe – from yellow and green through to pink, purple and a striking blood red – making it an exciting addition to numerous dishes. It forms in ‘fingers’ up to 50mm (2 inches) long and 20 mm (1 inch) in diameter. Cut one open and you’ll find it filled with juice vesicles that look like tiny pearls – hence the name caviar lime. Bite into one of these pearls and it’ll pop pleasantly in your mouth, releasing a limey-lemon flavoured juice.
The seeds germinate slowly and I’ve been told that cuttings can take their time to develop roots. Having said that, they are hardy and easy to grow.
If you’d like to know more about native citrus, see here.
And if you’d like more information on prices on finger lime plants and products, see here.
Microcitrus Garrawayae – Mount White Lime
Also known as Microcitrus garrawayi.
This is a thornless, understory tree found in the thickets of the tropical rainforest on the Cape York Peninsula region in far north Queensland.
It can grow up to 15m tall and produces small, thick leaves. Like it’s cousin the finger lime, the Mount White lime has a tube-like, yellow/green fruit with light green juice vesicles.
This native citrus is rare and hard to find (or get to) in the wild and so is currently protected.
Microcitrus Inodora – Russell River Lime
Also known as the large leaf Australian wild lime.
Found only in the lowland tropical rainforests between the Russell River and Bellenden Kerr in far north Queensland, this already rare native citrus has been threatened further by land clearing practices which have levelled areas of its preferred habitat.
It is a small shrub which reaches only 4m and has large, shiny leaves with tiny pairs of thorns on the stems. The fruits are yellowish green and oblong in shape.
Microcitrus Maideniana – Australian Wild Lime
Also known as citrus inodora var. maideniana and Maiden’s Australian lime.
So similar to Microcitrus inodora that it is sometimes considered a subspecies or variety of the plant we’ve just spoken about, the main visual difference is that its fruits have a sunken top.
Eremocitrus Glauca – Australian Desert Lime
Also known as desert lemon, native kumquat and limebush.
NB Although I’ve popped it under the Eremocitrus classification, as it was originally designated by W. T. Swingle, more up to date taxonomy puts all the Australian limes within the Citrus genus.
This native citrus crops up in 2 distinct regions – the rangeland interior of southern Queensland and New South Wales and a separate patch near Carrietown in South Australia.
Growing up to 12m in height, as is so often the case with Australian native flora (and fauna), it has some unexpected characteristics. When it is disturbed, it produces root suckers. It is apparently evergreen and shows good resistance to heat and cold, salinity and drought. If the rains come it will drop its leaves and subsist on the bark on its branches. In a brilliant display of evolution, it has thorns on its lower branches to deter kangaroos and cattle etc from grazing on it’s leaves and fruit, but no thorns higher up where such armoury isn’t needed.
In years with goods rainfall, the Australian desert lime produces plenty of small, intensely-flavoured, pale yellow-coloured fruit. They set fruit infrequently, but almost straight after flowering.
If you’d like to know more about citron cultivars, see here.
At home in the Kimberly in north west Western Australia and continuing over to the western areas of the Northern Territories monsoon-affected north, this plant is not only found in Australia but also in parts of South East Asia.
Growing only about 2m, it is a twinning vine which produces a small, round fruit.
As I noted above, whilst there has been little interest in cultivating the fruit of this particular native citrus, it may have a future as a rootstock for other fruit-bearing plants.
Also, whilst looking into the Paramignya trimera, I discovered that it has been used to treat cancer in traditional Vietnamese medicine for many years and that researchers in the west as now beginning to take note and run tests of their own on it.