Americas, tropics and subtropics of the Old World present
Throughout tropics and subtropics of the Old World, since 1930 adventive in various places in the Americas.
For a fuller synonymy, see Holttum 1976. This is a very variable species which has greatly multiplied with the Clearing of forest in the past 100 years. Plants examined from various sources have all been tetraploid; some experi- mental hybridization has been effected with C. hispidula (q.v.) and C. parasitica. It is probable that natural hybrids also occur; these are difficult to discriminate. Earlier authors did not distinguish between this species and its near allies, so that statements in literature are unreliable. Much more local study is needed.