The Rubiaceae (coffee family) is the largest and most poorly known woody plant family in the wet tropics. It contains approximately 13,200 species in 620 genera, of which 26 genera have more than 100 species. Psychotria has more than 2,000 species, which is larger than most plant families.
Recent inventory studies and rapid biodiversity assessments undertaken in the Old World Tropics, show that 10 to 20% of the total species diversity in some areas is from the Rubiaceae. Not only is the family significant in terms of biodiversity, but it also constitutes a large percentage of total biomass in tropical ecosystems. There are numerous hotspots of Rubiaceae diversity in the wet regions of the Old and New World Tropics (eg East and West Africa, Madagascar, SE Asia, Brazil, Costa Rica, Cuba, Peru and Ecuador), and also in the drylands of Madagascar, Angola, and Central America.
The need for further research on the Rubiaceae is substantial. For some regions the extent of ignorance is alarming and there is a clear lack of fundamental data, particularly in the Old World Tropics (mainly Madagascar and SE Asia). The current classification of the family is unstable, although great progress is being made with molecular systematics. There are numerous unresolved generic complexes (including the subfamilies, tribes, and subtribes), many undescribed genera, and several hundred undescribed species. There are more than 200 species without scientific names in Madagascar alone. The need for basic taxonomic knowledge is heightened by habitat destruction in the tropics.
Most species of Rubiaceae occur in the forest understorey, where their fruits, nectar and leaves provide important food resources for animal communities. The most economically valuable genera are Coffea (coffee), Genipa (genipapo, a fruit used to make a beverage and a dye), and Cinchona (quinine). Species of commercial importance include Psychotria ipecacuanha =Carapichea ipecacuanha (ipecacuanha, an expectorant), Pausinystalia johimbe (yohimbe, an aphrodisiac), Rubia tinctorum (madder, a dye), Uncaria gambir (gambier, an important tannin source), Uncaria (medicines), Calycophyllum (lemonwood, a timber), Neolamarckia cadamba (timber tree), and Gardenia (perfume & ornamentals).
Coffee is by far the most economically important member of Rubiaceae, being the second most important traded commodity after oil. Worldwide, more than 25 million people depend on coffee for their livelihoods. Rubiaceae also provide local indigenous populations with remedies against malaria and other diseases, body paints, edible fruits and construction wood. Most species of Rubiaceae are indicators of forest health and condition. For example certain species of coffee will only grow in good quality, primary forest. Given the abundance and ubiquity of this family in humid and dry tropical forest ecosystems, the identification of Rubiaceae is often vital to the understanding of tropical ecology.
Kew houses the world’s most comprehensive herbarium collection of Rubiaceae. There are about 250,000 plant specimens including about 7,000 types, curated and maintained by the core Rubiaceae team. These collections together with specimen, taxon and classification/distribution databases provide the main resources for supporting our research activities. These are particularly important for supporting Kew’s rapid biodiversity assessment work in Africa and Madagascar and the production of taxonomic and systematic treatments for Rubiaceae. These resources also provide the basis for our work on conservation, ecological niche modelling and climate change, and provide data for the compilation and upkeep of the on-line World Checklist of Rubiaceae and associated bibliography.
Kew is the only institute able to support a worldwide genus/species identification facility for the family (eg for checklists and inventories of tropical regions). This is possible due to the strength of the collections, the extremely high standard of curation, and the expertise of staff. The Rubiaceae team work with a global network of partners and collaborators from 29 institutes in 16 countries including researchers and PhD students. Some partnerships go back many years.