Cola usambarensis

References

1. [1]Protabase - Plant Resources of Tropical Africa. — http://www.prota.org ↩︎An excellent on-line database with detailed information on over 3,200 species of useful plants of Africa.
2. [2]Flora of Tropical East Africa — Beentje H.J. · Royal Botanic Gardens; Kew. · 2002 · http://plants.jstor.org/search?st=396814 ↩︎Available on-line, a modern flora of East Africa.
3. [3]African Flowering Plants Database — Conservatoire et Jardin Botaniques. · http://www.ville-ge.ch/musinfo/bd/cjb/africa/recherche.php ↩︎Contains information on over 150,000 plant names (including synonyms) giving a description and habitat, plus a distribution map.
4. [4]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.