Canthium
Canthium is a genus of flowering plants in the family Rubiaceae. They are shrubs and small trees. The leaves are deciduous and the stems are usually thorny. Distribution. "Canthium" species are predominantly found in Southeast Asia, especially in Thailand and the Philippines. A small number of species is found in India, Sri Lanka, and Bangladesh. Only a limited number of species is found on the African continent, especially in Southern and East Africa. 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. The genus was further reduced by the transfer of species to "Peponidium" and "Pyrostria". In 2016, two "Canthium" species endemic to the Philippines were transferred to a genus of their own, "Kanapia". 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.