R. senegalensis and R. umbellulata are the two most widespread species and they are found from Senegal to Sudan to Botswana.

However, most species are more restricted in distribution area and they are often found in either West or East Africa.

[2] Endophytic bacteria are housed in the intercellular space of the leaf mesophyll tissue.

The bacteria are identified as Burkholderia, which is a genus that is also found in the leaves of other Rubiaceae species.

[3][4] The hypothesis is that these endophytic bacteria provide chemical protection against insect herbivory.