This genus is in the subfamilyAurantioideae, which also includes genus Citrus. It is in the subtribe Clauseninae, which are known technically as the remote citroid fruit trees.[4][5]
The genus includes shrubs and trees. Some species are variable, with many forms. C. anisata, for example has been described as a shrub under a meter tall and as a tree of 20 metres (66 ft).[4] The leaves of these plants are pinnate, divided into leaflets. The inflorescence varies in form, but is generally a cluster of several flowers with 4 or 5 petals and sepals. The fruit is a berry which lacks the pulp of many other fruits in the citrus family.[3] The genus can be distinguished from related plants by the presence of a gynophore, a structure supporting the ovary in the flower. It looks very different in the various species, however, and can be hard to recognize.[4]
Uses
C. anisata is a tree used for its wood,[7] and in traditional medicine.[8]C. excavata is used medicinally in Asia for a variety of conditions, including snakebite, malaria, dysentery, and HIV infection.[9] Some species, such as C. indica and C. lansium (wampi), produce edible fruit. Wampi is cultivated as a fruit tree, and though it is only a remote relative of citrus, it can be grafted to various citrus trees. There are sour, sweet, and intermediate varieties of C. lansium.[4]
Fossil record
A Clausena leaf fossil from the Oligocene of Ethiopia, represents so far the oldest record of the genus.[10]
Diversity
The taxonomy of the genus is unclear.[4] There are between about 15 and 30 species.[3] Many formerly used names were made synonyms in a 1994 revision.[11]
^ abForster, Paul I. (2000). "Clausena smyrelliana (Rutaceae: Aurantioideae), a new and critically endangered species from south-east Queensland". Austrobaileya. 5 (4): 715–720. JSTOR41738949.
^Citrus linczangensis sp. n., a Leaf Fossil of Rutaceae from the Late Miocene of Yunnan, China by Sanping Xie, Steven R Manchester, Kenan Liu and Bainian Sun - International Journal of Plant Sciences 174(8):1201-1207 October 2013.