Australian Finger Lime - Citrus australasica. Fruits.

Australian Finger Lime - Citrus australasica

The Australian finger lime plant (Citrus australasica) is a thorny understorey shrub or small tree of lowland subtropical rainforest and dry rainforest in the coastal border region of Queensland and New South Wales, Australia. It has edible fruits which are under development as a potential new commercial crop. According to the Swingle system it is not part of the genus citrus, but in a related genus Microcitrus (Microcitrus australasica).

The Australian Finger lime, as its name suggests, is native to Australia, specifically to the rainforests of the border ranges of Southeast Queensland and Northern New South Wales. The plant is 2–7 metres in height. The first leaves are minute linear cataphylls; these gradually merge into juvenile foliage which, in turn, merges into the mature foliage, the leaves of which are smaller than those of any other True Citrus Fruit Tree with the exception of Citrus glauca, when the latter occurs in very dry situations. Leaves are small, 1–6 cm long and 3–25 mm wide, glabrous, with a notched tip and crenate towards the apex. Flowers are white with petals 6–9 mm long.It produces finger-shaped fruit, up to 10cm long, with thin green or yellow skin and greenish-yellow compressed juice vesicles that tend to burst out when the skin is cut. A pink to red-fleshed form with red to purple or even black skin (known as Citrus australasica var. sanguinea) also occurs in the wild.

The Australian Finger lime has been used by the Aboriginal people for thousands of years.Documentation has sited that it originated without human assistance. Early settlers consumed the fruit and retained the trees when clearing for agriculture. Colonial botanists suggested that they should be cultivated. The Australian Finger lime was received from New Wales, Australia as budwood by Dr. Joe Furr in 1965. He donated them to the University of California, Riverside in 1966. Finger lime trees prefer sheltered rainforest or sub-rainforest habitats for prolific growing. Overexposure to full sun will cause the trees stress, thus producing poor fruit yields. Though common in Australia, their global presence is still obscure.

There are several different Australian Finger lime varieties, which is botanically classified as Citrus australasica, all of which maintain the same shape and constitution: The Alstonville variety is green and seedless. Judy's Everbearing is a light green to pink skinned fruit with pale rose pulp. Pink Ice is similar to Judy's Everbearing, its skin ruby tinged brown with rose colored pulp. The Purple Viola and Jali red share the same ruby coloring pulp while their skin deepens with age.

The  Australian Finger lime has been recently popularised as a gourmet bushfood and is known as the caviar of citrus. Their aromatic smooth but pebbled skin appears in a triad of colors and the flesh, rather than pulpy, holds caviar-shaped vesicles that pop crisply in your mouth with an assertively tart punch. When the fruit is cut in half, the juice vesicles, which are under pressure, ooze out as if erupting from a mini-volcano. Unlike the tender, tear-drop-shaped juice sacs in standard citrus, the translucent, greenish-white or pinkish vesicles in finger limes are round and firm, and pop on the tongue like caviar, releasing a flavor that combines lemon and lime with green and herbaceous notes. The rind oil is also quite aromatic, and contains isomenthone, which is common in mint but rare in citrus.Fruit pulp color intensifies during the last phase of fruit maturity.

The fruit juice is acidic and similar to that of a lime. Marmalade and pickles are also made from finger lime. The finger lime peel can be dried and used as a flavouring spice. Finger limes can be used in cooked applications but are best featured as a garnish or raw addition. Finger limes compliment seafood, chicken, melons, spirits and cream based desserts. Use Finger limes to add slight crunch and bright citrus flavor to top off your oyster shooters, seared scallops or grilled salmon. Slice avocado or melons and sprinkle Finger lime caviar on top, add sea salt and enjoy a refreshing and satisfying afternoon snack. Finger limes add a great deal of sophistication to cocktails and spirits, or used as a floating garish. Use Finger lime caviar as garnish for sushi, key lime cheesecake, ceviche, grilled shrimp or any dish where a burst of citrus flavor would be complimentary.

Commercial use of finger lime fruit started in the mid-1990s in boutique marmalades made from wild harvested fruit. By 2000 the finger lime was being sold in restaurants, including the export of fresh fruit. The finger lime has been recently grown on a commercial basis in Australia in response to high demand for the fruit. There is an increasing range of genetic selections which are budded onto citrus rootstock. With the sudden high market demand for the fruit the primary source of genetic material for propagation has been selections from wild stock.

Source:
https://en.wikipedia.org/wiki/Citrus_australasica
http://citruspages.free.fr/australian.html
http://articles.latimes.com/2009/dec/23/food/la-fow-marketwatch18-2009dec23
http://www.specialtyproduce.com/produce/Finger_Limes_6704.php