Canthium

Canthium is a genus of flowering plants in the Rubiaceae family. They are shrubs and small trees. The leaves are deciduous and the stems are usually thorny.

Distribution

They are native to India, Sri Lanka, eastern and southern Africa, Madagascar, Seychelles, China, Southeast Asia, New Guinea, and some of the islands of the Pacific.

Taxonomy

Canthium was named by Jean-Baptiste Lamarck in 1785 in Encyclopédie Méthodique. The name is a latinisation of "kantankara", a Malayalam name from Kerala for Canthium coromandelicum. Kantan means "shining" and kara means "a spiny shrub". The biological type for the genus consists of specimens originally described by Jean-Baptiste Lamarck as Canthium parviflorum but this species is now included in Canthium coromandelicum.Canthium is a member of Vanguerieae, a tribe that is monophyletic and easily recognized morphologically, but in which generic boundaries were, for a long time, very unclear.Canthium was especially problematic, and until the 1980s, it was defined broadly and known to be polyphyletic. Psydrax was separated from it in 1985, as was Keetia in 1986. These were followed by Pyrostria and Multidentia in 1987. The subgenus Afrocanthium was raised to generic rank in 2004, followed by Bullockia in 2009. A few species were transferred to Canthium from Rytigynia and other genera in 2004 but the final circumscription of Canthium will remain in doubt until phylogenetic studies achieve greater resolution for the clade containing Canthium coromandelicum and its closest relatives.