EUPHORBIACEAE OF MADAGASCAR

INTRODUCTION

Euphorbiaceae is the sixth largest plant family in the world. Approximately 700 indigenous species in c. 60 genera occur in Madagascar. The plants occur all over Madagascar, in pristine rain forest as well as in disturbed habitat, from the Masoala Peninsula to Toliara. They can be large trees to small herbs. Because of their very small flowers, this family is relatively poorly studied in Madagascar. These web pages report on the results of the "Euphorbiaceae of Madagascar" project at the Royal Botanic Garden, Kew.

FLORISTIC INVENTORY

RBG Kew is a major collaborator in the Euphorbiaceae volumes of the "Flore de Madagascar et des Comores" which is coordinated by Dr Gordon McPherson at the Missouri Botanical Garden. Other contributing institutions are the Museum National d'Histoire Naturelle, Paris, and the Canadian Museum of Nature, Ottawa. So far, treatments of 26 of the 60 genera have been produced including the large genus Croton (150 endemic species in Madagascar) by Alan Radcliffe-Smith (Kew). Other major genera are Euphorbia (c. 125 endemic species in Madagascar) which is the subject of a PhD thesis by Thomas Haevermans (MNHN Paris), co-supervised by Dr Petra Hoffmann in Kew. The next biggest and very difficult group is the genus Phyllanthus (c. 70 species) which the subject of a PhD thesis based at the university of Antananarivo (see below). During our fieldtrips we still regularly encounter plants that are new to science, which are then described as new species. One recent example in Euphorbiaceae is Suregada celastroides Radcl.-Sm. & Petra Hoffm. from Mt Vatovavy near Ifanadiana. Reference: Radcliffe-Smith, A. , Hoffmann, P, Ranaivojaona, R.& H. Ralimanana: Suregada celastroides Radcl.-Sm. & Petra Hoffm. (Euphorbiaceae), a new species from eastern Madagascar, Kew Bulletin, in press.

Hélène in the Kew office, Tana	Collecting in Mayotte	Phyllanthus decipiens (Baill.) Müll. Arg

TRAINING AND CAPACITY BUILDING

As part of RBGKew's Euphorbiaceae research, a PhD project entitled "Systematics and Biogeography of Madagascan Phyllanthus" started in 2002 at the Departement de l’Ecologie et Biologie Végétale, University of Antananarivo. The candidate, Hélène RALIMANANA, has already undertaken several fieldtrips in Madagascar and Mayotte, as well as two study visits to the herbaria of Paris and Kew. She will also participate in the 17th AETFAT congress on Tropical African Botany in Ethiopia. The genus Phyllanthus is represented in Madagascar by c. 60 species, most of which are endemic, i.e. they do not occur elsewhere in the world. The thesis will include a biogeographical (GIS) analysis and IUCN conservation ratings for all species. A DEA project has commenced at the same time on the subject "Etude systematique et biogeographique de Phyllanthus casticum et Phyllanthus nummulariifolius a Madagascar", undertaken by Bakolinantenaina ANDRIANAIVORAVELONA and examining the variability of the closely related taxa in these two species complexes.

PLANT CONSERVATION

A main objective of Kew's work is plant conservation. The natural vegetation of Madagascar is unique in the world but also highly endangered by clearing for agriculture and fire wood, as well as bush fires. To assess the threat to plant species, we are using IUCN threat categories developed by the World Conservation Union. The most endangered plants will be included in the Red List of Threatened Species. This list is used by decision makers and NGOs to set priorities for conservation. Thomas Haevermans (MNHN Paris) has assessed all 166 species, subspecies and varieties of the genus Euphorbia in Madagascar, many of which (especially succulents) are illegally exported from Madagascar. IUCN conservation assessments are now a part of most research at Kew. Recent examples are the revision of the genus Petalodiscus by Petra Hoffmann (Kew) and Gordon McPherson (MBG), and the forthcoming revision of Phyllanthus by Helene Ralimanana.

References: Hoffmann, P. & McPherson, G.: Revision of Petalodiscus including Blotia (Euphorbiaceae-Phyllanthoideae), Annals of the Missouri Botancal Garden, submitted 2002

PHYLOGENETIC ANALYSIS

RBG Kew is also working on the evolution of flowering plants as a whole. Because Euphorbiaceae is one of the largest plant groups, a collaborative Kew project with Austrian and US institutions uses DNA sequence analysis to study the relationships within this plant family worldwide. To apply this technique, small quantities of quickly dried leaves are needed. On plant collecting trips in Madagascar we have collected important genera such as Antidesma, Meineckia, Petalodiscus, Thecacoris, Uapaca, and Wielandia for this study.

Reference: Wurdack, K., Hoffmann, P, Chase, M. W., Samuel, R., de Bruijn, A. & van der Bank, M. Molecular phylogenetic analysis of Phyllanthaceae (Phyllanthoideae, Euphorbiaceae s.l.) using plastid rbcL sequences, in prep.

CONTACT

Petra Hoffmann, Malpighiales Section, Herbarium, Royal Botanic Gardens, Kew, Richmond Surrey, TW9 3AB, UK. Email
Hélène Ralimanana, R.B.G. Kew,Lot II J 131 B, Ambodivoanjo - Ivandry,00101 Antananarivo Email: