The Rubiaceae (Coffee Family) of Madagascar

INTRODUCTION

The Rubiaceae, or Coffee family, is the largest family of woody plants in Madagascar, second only to the orchids (Orchidaceae) in total number. It contains around 850 species, most of which are found nowhere else in the world. Species of Rubiaceae are important components of the forest understorey, and often make up a large part of the total forest diversity and biomass. They also provide important sources of food for animals, including lemurs. Despite its size and importance the Rubiaceae family is poorly known in Madagascar. The aim of this web page is to provide and overview of the work being undertaken on the coffee family in Madagascar by the Royal Botanic Gardens, Kew and its partners in Madagascar.

CATALOGUING THE RUBIACEAE DIVERSITY OF MADAGASCAR

With around 850 species the Rubiaceae account for 7% to 9% of the total natural plant diversity of Madagascar. The problem is, only 650 species are currently known to science, leaving more than 200 species without scientific names. Many groups once though to contain only a few species have now been shown to consist of a considerable number of species. For example, a recent survey by a PhD student at Parc Botanique et Zoologique de Tsimbazaza (PBZT), has shown that one group of Rubiaceae (the genus Hyperacanthus) unknown in Madagascar in 1997, now comprises 50 tree species. Without scientific names plant species cannot be properly catalogued, giving considerable problems for plant conservation. How can we conserve the flora of Madagascar if we do not know what species exist, or where they are found? RBG Kew, in collaboration with its Malagasy partners and institutes world-wide, is addressing these problems by undertaking a rapid assessment of the Rubiaceae in Madagascar.

SPECIMEN COLLECTING

There is a need to gather more plant specimens from Madagascar, as many species are still insufficiently known and there are regions for which we have too few collections or none at all. Since 1997 numerous collecting trips have been made to selected areas throughout Madagascar. Plants are collected and made into herbarium specimens, which provide us with a permanent record of Madagascar's flora. The herbarium specimens are fundamental for plant conservation, giving detailed, precise and verifiable information on Madagascar’s flora. The photograph below left was taken at Parc National d’Andohahela, near Tolagnaro, and shows plant collecting by staff from RBG Kew and Parc Botanique et Zoologique de Tsimbazaza (PBZT). The Photograph below right shows a new genus (Robbrechtia grandiflora), recently discovered in the humid forests of eastern Madagascar and described by Petra De Block (National Botanic Gardens, Belgium).

TAXONOMIC RESEARCH

Taxonomy, the naming and classification of organisms, is vital to the understanding of the natural world. A considerable amount of taxonomic study on the Rubiaceae of Madagascar is now underway, within the framework of a collaborative network. For example, students at the Parc Botanique et Zoologique de Tsimbazaza (PBZT) and the University of Antananarivo are busy describing new species and producing new classifications. The eventual aim is to produce a complete work on the Rubiaceae of Madagascar, but in the short-term we aim to produce a detailed species checklist with species conservation assessments.

A FOCUS ON COFFEE

Madagascar is home to 55 species of coffee (Coffea spp.), the largest concentration of species in the world. Every one of these 55 species is exclusive to Madagascar; the diversity of Madagascan coffees is unparalleled. Due to the importance of this plant group, RBG Kew and PBZT initiated a project in 1997 to study the coffees of Madagascar. Since 1999, we have described 15 new species of coffee, including several species collected by us in remote parts of Madagascar.

Coffea sp. nov. One of the newly discovered species of coffee, found for the first time in 1996 at Tsingy de Bemaraha, western Madagascar. The bizarre winged fruits are unlike any other coffee species.

CONTACT

Aaron Davis, Herbarium, Royal Botanic Gardens, Kew, Richmond Surrey, TW9 3AB, UK. E-mail:

Franck Rakotonasolo, Parc Botanique et Zoologique de Tsimbazaza, B.P. 4096, Tsimbazaza, Antananarivo, 101, Madagascar. E-mail: