fragrant scent. Another use for its oils would be for a cleaner spray. Many oil cleaner sprays contains the chemical limonite, which are most commonly made using limes. While not necessarily the most primary use, the Citrus australis can also be used for creating hybrids. As it is one of the most commonly seen vigorous native Australian species, it is worth noting that they are not resistant to viroid infection. This makes them an ideal target for trying to trace the history of the Citrus australis. An example of this is the Sydney hybrid. The Sydney hybrid is a result of a hybrid between the Citrus australis and the Citrus australasica, and is found primarily in Australia. Other names for the Sydney hybrid include Microcitrus x virgate H. Hume or Citrus x virgate Mabb. The appearance of the lime when compared to its parents most commonly resembles the Citrus australasica with the size of the leaves and the shape of the fruit. The Sydney hybrid is elongated, about with a rounded apex, compared to the Citrus australis which is more circular in shape. It is also known to be very drought-resistant. While the tree for the Citrus australis found in nature can get to about high, it can also be grown in a garden as a small shrub or tree, which will typically stay at about high. Although the plant when young will have many thorns to protect it when vulnerable, as it grows it will becomes less prickly, making the plant easier to maintain. As the plant is grown on volcanic soils, the wood of the Citrus australis is close-grained and suitable for cabinet making and engravings. History The Citrus australis is a Microcitrus, which is a cluster that contains the Citrus australis as well as other limes such as the New Guinea lime or the New Guinea wild lime. Through DNA replication and phylogenetic relationships, it is believed that the Citrus australis has evolved over millions of years, from a primitive ancestral type that underwent speciation in Australia and New Guinea. There are two phases of speciation, where the first phase comes from the late Miocene of East and Southeast Asia. These include the Citrus medica (citrons), Citrus maxima, Citrus reticulata, Citrus hystrix, Citrus ichangensis, Citrus japonica, and Citrus mangshanensis. The second phase of speciation is from the early Pliocene of Oceania and include three Australian species of