Australia has six species of native citrus, with the most well known and cultivated species being the finger lime. The Australian finger lime (Citrus australasica) is native to the rainforests of the border ranges of SE Queensland and Northern NSW. In its natural habitat the finger lime grows as an understorey shrub or tree up to 6 metres in height on a range of soil types.Trees are thorny, producing distinctive finger shaped fruit up to 12 cm long with a typically green-yellow skin and pulp. There is also a naturally occurring pink-red fleshed form of finger lime known as Citrus australasica var. sanguinea. In the wild, finger limes are genetically very diverse, with trees and fruit varying in size, shape, colour and seediness. The pulp of the fruit is unique with separate juice vesicles that resemble caviar. The individual juice vesicles (sometimes referred to as crystals) are compressed inside the fruit and burst out when the fruit is opened. Demand for finger limes has grown steadily over the past decade, mainly as a result of its bush food status, unique caviar-like pulp and attractive colour range, with most interest coming from the restaurant trade.
Citrus is rich in vitamin C, vitamin P and calcium and is beneficial in the digestion of protein-rich foods. Citrus fruit also changes the over-acid condition of the body to an alkaline one by its heavy fruit calcium contents, which supply the bones, teeth, blood and nervous system with calcium and phosphorous. Citrus juices are a great aid to nervous persons, and are used in neurasthenia with fine results. Citrus juices relieve and prevent nervous indigestion and halitosis (bad breath) due to upset digestion.