Plant Profiles: The Caviar Lime

Oh dear, we thought we have seen (and grown) it all... the Buddha Hand Citrus( Citrus Medica Digitata), the Kaffir Limes ( citrus Hystrix) and the fashionable Meyer's Lemons! But alas there is a charming little newcomer trying to get into our botanical homes. The Caviar Lime or Finger Lime, Citrus australasica (syn. Microcitrus australasica).

Totally unknown to most gardeners and fruit lovers, this citrus species starts to make its timid entry on the European and US market.

We are talking about a relatively tiny, very thorny shrub or small tree of lowland subtropical rain forest and dry rain forest in the coastal border region of Queensland and NSW in Australia.

The plant is 2–7 metres in height. Leaves are small and glabrous, 1–6 cm long and 3–25 mm wide. Flowers are white, flushed with purple, with 6–9 mm long petals and not very showy. 

 

"The seven species of Citrus previously known as Microcitrus are the result of millions of years of slow evolution from a primitive ancestral types. This type may have resembled C. warburgiana, the New Guinea species, which has small leaves and small, nearly spherical fruits. From such an ancestral form, one line of evolution produced the so-called native orange, round lime, or Dooja (C. australis), that grows to a large tree and has subglobose fruits much larger than those of C. warburgiana, with long, slender, pointed, more or less twisted pulp-vesicles. Another line of evolution culminated in C. inodora and C. maideniana, highly specialized forms showing adaptations to tropical rain forests, with large leaves and paired spines; a third line of evolution led to the small-leaved species C. australasica and C. garrawayae, both with long-ovoid or very elongated cylindric fruits.

Distribution

These remarkable citrus fruits are extremely interesting, in that they show how evolution has proceeded in regions isolated as Australia and New Guinea have been during the last twenty or thirty million years since they were cut off from all other land masses. The evolution of other citrus fruits is not so easily followed, since Citrus, Fortunella, and Poncirus did not originate in regions that were geographically isolated in definitely dated geologic eras. The group contains seven species, five of which are native to Australia with the other two found in New Guinea. The Australian species occur in rainforests and their margins from Cape York Peninsula south to the northern rivers of New South Wales. They produce small, round or finger-shaped fruit, with a pleasant but very acid juice. 

Uses

They have a close relationship with conventional citrus fruit in the genus Citrus. Australian native citrus species are able to hybridise with a range of other citrus species. This ability, along with  drought and salinity tolerance and disease resistance, has long attracted the interest of citrus researchers and breeders. Improved selections and hybrids of native citrus also have potential in their own right for commercial production. Fruit is used in a range of sweet and savoury processed products, such as marmalades and sauces, and is in demand by chefs producing ‘Australian Native Cuisine’ dishes. Traditionally most fruit has been harvested from the wild. Commercial orchard production  began in the last decades of the twentieth century ."

 

source: http://users.kymp.net/citruspages/australian.html#finger

 

The fruits though are real fun! Cylindrical, 4–10 cm long, sometimes slightly curved, coming in different colours and they look like fingers or tiny sausages.The skin can be green, orange, yellow or purplish red, depending on the type and has a distinctive bush aroma.

The fun comes when you cut the fruit  and discover the juicy, round pearls which are similar to caviar in size and texture. The colour of these pearls ranges from white to pink, lime green and yellow. When you bite into the finger lime pearls, they burst in your mouth, releasing their tangy lime flavour.

For more information about the Microcitrus and other types of citrus trees you can browse these excellent pages: 
Vivaio Oscar Tintori: http://www.oscartintori.it/
Pepinieres Bache: http://site.plantes-web.fr/baches/1292/boutique/49819/citrus_australasica.htm
Jardin Botanico Mundani from Mallorca: http://jardin-mundani.com/

Citrus Pages: http://users.kymp.net/citruspages/home.html
                        http://users.kymp.net/citruspages/australian.html#finger