[2] As accepted by Plants of the World Online;[2] World Flora Online only accepts 20 species; B. ameero, B. bullata, B. carteri Birdw., B. dalzielii, B. dioscoridis, B. elongata, B. frereana, B. globosa, B. microphylla, B. nana, B. neglecta, B. ogadensis, B. ovalifoliolata, B. papyrifera, B. pirottae, B. popoviana, B. rivae, B. sacra, B. serrata and B.

[8] They are native to the countries (and regions) of Benin, Burkina, Cameroon, Central African Republic, Chad, Eritrea, Ethiopia, Ghana, India, Ivory Coast, Kenya, Mali, Niger, Nigeria, Oman, Senegal, (island of) Socotra, Somalia, Sudan, Tanzania, Togo, Uganda, West Himalaya and Yemen.

[2] In 1998, the International Union for Conservation of Nature (IUCN) warned that one of the primary frankincense species, Boswellia sacra, is "near threatened".

In a 2006 study, an ecologist at Wageningen University & Research claimed that, by the late-1990s, Boswellia papyrifera trees in Eritrea were becoming hard to find.

This species, found mainly in Ethiopia, Eritrea, and Sudan, accounts for about two-thirds of global frankincense production.

[9] The four main species of Boswellia, B. sacra (synonyms B. carteri and B. bhaw-dajiana), B. frereana, B. papyrifera, and B. serrata,[3] produce true frankincense, and each type of resin is available in various grades.