Citrus australasica
A thorny Australian shrub producing edible 'caviar-like' fruit.
Citrus australasica, commonly known as the finger lime or caviar lime, is a thorny understorey shrub or small tree native to lowland subtropical rainforest in the coastal border region of Queensland and New South Wales, Australia. It is notable for its edible fruits, which are grown as a commercial crop and have been popularized as a gourmet bushfood.
- First described by
- Ferdinand von Mueller (1859)
Lore & Background
The finger lime was first described by Australian botanist Ferdinand von Mueller in 1859 in the first volume of his work Fragmenta phytographiæ Australiæ. American botanist Walter Tennyson Swingle, in a 1915 review, placed all four Australian species in a new genus Microcitrus, citing morphological differences from cultivated Citrus. However, British botanist David Mabberley, in a 1998 paper, discussed the mix of morphological features across the subtribe Citrineae and the ease of crossing species, and subsequently restored the finger lime to the genus Citrus.
First Peoples living along the east coast of Australia used finger limes for hydration and to treat skin infections and cuts. Early settlers consumed the fruit and retained the trees when clearing for agriculture. Colonial botanists suggested cultivation due to the lack of citrus alternatives. Commercial use began in the mid-1990s with boutique marmalades from wild harvested fruit; by 2000 the fruit was sold in restaurants and exported fresh.
The finger lime is susceptible to various insect pests and is a known host to the Queensland fruit fly Bactrocera tryoni under natural conditions. Research since the 1970s indicated a wild selection was highly resistant to Phytophthora citrophthora root disease, leading to cross-breeding for disease-resistant rootstock. In 2020, researchers began working with the species to develop solutions for Citrus greening disease.
Reader's Guide
Citrus australasica holds significance as a native Australian citrus species that has transitioned from traditional use by Indigenous peoples to a modern commercial gourmet crop. Its fruit, containing globular juice vesicles known as 'lime caviar,' is valued for its effervescent tangy flavour and is used as a garnish, in recipes, marmalades, pickles, and as a dried spice. The species is also important in horticultural research: its resistance to Phytophthora citrophthora root disease has driven cross-breeding programs to develop disease-resistant citrus rootstock, and since 2020 it has been studied for solutions to Citrus greening disease. The finger lime is thought to have the widest range of colour variation within any Citrus species, and the CSIRO has developed hybrids crossing it with standard Citrus species to produce fruits in many colours. Its conservation status is least concern, and it is not a host to the Queensland fruit fly, benefiting Australian growers.
Did You Know?
- The finger lime is a known host to the Queensland fruit fly Bactrocera tryoni under natural conditions, requiring Australian growers to apply extra treatment before export.
- A wild selection of Citrus australasica has been highly resistant to Phytophthora citrophthora root disease since research in the 1970s.
- The fruit contains vitamin C, folate, potassium, vitamin E, and polyphenols.
- The CSIRO has developed hybrids crossing finger lime with standard Citrus species to produce fruits in many colours.
Frequently Asked Questions
What is Citrus australasica?
It's a thorny understorey shrub or small tree native to the coastal border region between Queensland and New South Wales, Australia. In the bushfood world it goes by the names finger lime or caviar lime, and it's cultivated commercially for its edible fruit.
What makes finger lime fruit so distinctive?
The small, finger-shaped fruits are packed with tiny bead-like segments that look and pop like caviar when squeezed, which is how the nickname stuck. That caviar texture combined with a bright citrus flavour is what sets it apart from every other citrus you'd find in a kitchen.
Where does Citrus australasica grow in the wild?
It's native to lowland subtropical rainforest along the coastal border between Queensland and New South Wales. It typically sits in the understorey layer rather than forming part of the tall canopy.
Who first formally described the finger lime species?
Botanist Ferdinand von Mueller published the first scientific description of the species in 1859. Of course, Aboriginal and Torres Strait Islander peoples had known about and used the fruit long before that European documentation.
How do chefs actually use finger lime in a dish?
The caviar-like pulp is usually popped onto a finished plate as a final garnish, adding a sharp citrus burst to seafood, desserts, or cocktails. It's treated as a premium bushfood accent rather than a cooking citrus you'd juice into a sauce.
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