Malagasy endemics

Euphorbia pulcherrima
not necessarily endangered

One of the largest genera of flowering plants is Euphorbia with approximately 2,000 species. This large genus belongs to the very diverse Family Euphorbiaceae with at least 7,500 species. The variation within this genus is astonishing, from low-growing garden weeds called spurges to giant, cactus-like succulents that rival in size with North American sahuaro and organ-pipe cacti. The most famous member is most likely Euphorbia pulcherrima, better known as Poinsettia indigenous to Central America and widely used in Christmas displays all other the world.

 

Isotype of
Euphorbia mananarensis

Madagascar is the home of at least 170 native mostly endemic Euphorbia species. Nearly all of them are listed in the CITES Appendices I and II as they are threatened by habitat loss and illegal collection of wild plants. The absence of a reliable taxonomy makes it particularly difficult to identify these plants, even when fertile, and thereby compromises the application of CITES regulations that are in place to protect them. Many Malagasy species of Euphorbia are illegally collected in the wild by unscrupulous collectors and internationally traded, presenting significant threats as a result of overexploitation, sometimes leading to the total decimation of entire populations.

DNA barcoding can provide species-level identification irrespective of developmental stage and the presence of flowers or fruits and may be a promising tool for monitoring and controlling trade involving those threatened species. A group of researchers from France have now published a first study on 41 Malagasy Euphorbia species in which they successfully tested several markers including the ones proposed by the plant barcoding community. 

Currently, all succulent species of Euphorbia are covered under the CITES convention. Yet, it is not always possible to determine whether a plant, cutting, seed or other propagule belongs to a succulent species, and as a consequence, material of other species may erroneously be subjected to CITES control. Moreover, some succulent Euphorbia currently covered under CITES are in fact common and widespread, and international trade does not represent a threat, yet it is often impossible to distinguish them from other succulent species that are highly threatened. Reliable barcoding procedures for all Malagasy Euphorbia could help resolve these issues, enabling control for those species that require it while allowing trade for those that are not threatened, and thereby providing a much-needed source of sustainable income for Madagascar.