Hyphaene – Project description
The African palm flora
The palm family is composed of about 185 genera and 2485 species (Dransfield et al., 2008), distributed principally in tropical regions, but extending with lower diversity into subtropical and temperate regions. The African palm flora (excluding Madagascar) is relatively low, in numbers of both genera and species, when compared with other parts of the tropics (Dransfield, 1988). Indeed, continental Africa is represented by 17 genera and 65 species of palms, most of them present in the lowland tropical regions of the continent (Stauffer et al., 2014). Yet some African palm genera (e.g. Hyphaene, Raphia) are still incompletely known or remain seriously under-collected. Furthermore, a large amount of the available herbarium specimens are fragmentary and hence largely uninformative for taxonomic studies. An important effort of collection is needed for an accurate taxonomic assessment at the species level.
The palm family was studied at a continental scale by Tuley (1995) and several treatments have been proposed as part of floristic inventories at the regional or country level (e.g. Dransfield, 1986, 2010; Chapman & Chapman, 2001; Aké Assi, 2002; Harris, 2002; Aké Assi et al., 2006; Hawthorn & Jongkind, 2006; Sosef et al., 2006; Baker, 2008; Lisowski, 2009; Lejoy et al., 2010; Couvreur et al., 2013). The African palm fossil record is limited but available data provide an outline of palm evolution from the Late Cretaceous through the Neogene, the earliest unequivocal record for the continent attributed to the Campanian, between 83.5 and 70.6 Mya (Pan et al., 2006). Palms are conspicuous components of several vegetation types in Africa and are of great economic significance both to subsistence and intensive commercial agriculture (Dransfield, 1988). Palms also rank among the most economically important plants for African populations. The relatively low number of species present in the continent is contrasted by the extremely high number of identified uses. For many taxa (e.g. Borassus, Elaeis, Hyphaene, Laccosperma, Raphia) almost all plant organs are exploited, presenting a wide range of uses, and this has been documented in several excellent publications (e.g. Burkill, 1997; Diniz & Martins, 2002; Sunderland, 2003; Latham & Konda, 2007).
Why is field work critical for improving our understanding of these palms?
Some African palm genera, in particular the Doum palms (Hyphaene spp.), remain poorly known and severely under-collected. A large amount of the available herbarium specimens are either fragmentary or not sampled in a proper way, and hence are largely uninformative for taxonomic study and identification. A recent visit to the herbarium of Munich (M), repository for many of the type specimens associated with Hyphaene and described by the Bavarian palm expert Carl P. von Martius, showed that most samples are only composed of fragmentary leaflets or fruits, providing limited information from a taxonomical point of view (see Ouattara and Stauffer, 2014 for details on Raphia sudanica, for example).
Moreover, misleading identifications of herbarium samples in Hyphaene appear common, due to the fact that they can be easily confused with the closely related genera Borassus and Medemia. Difficult access to wild populations of Hyphaene species has hindered obtaining complete and fertile samples. Populations in this group are distributed in regions that require special logistic effort, with collecting ideally benefiting from local partners able to co-organize field work during the seasons when reproductive samples are available. In spite of the floristic and botanical efforts undertaken by the Herbaria of Leiden and Kew Gardens in tropical Africa (cf. Dransfield, 1986 for details), relatively little progress was made toward a complete sampling of wild populations of Hyphaene.
The extremely difficult conditions for field work with Hyphaene in the savannahs of Eastern Africa were highlighted by Dr. John Dransfield, world authority on palms at Kew Gardens, who was recently contacted in the frame of the current project proposal:
“I believe the major problem in Hyphaene remains what goes on in the Horn of Africa. In fact, without new material from there it will be very difficult to resolve things. Most unfortunately, this is one of the most seriously bad places on earth to do fieldwork…”
Indeed, during several collecting expeditions in African savannahs (e.g. Ghana, Ivory Coast, Senegal) we have already experienced challenging conditions and extreme temperatures, and this in part may reflect why such field work, fundamental for the taxonomic study of these palms, has been neglected by local and foreign botanists. It is clear that successfully field work in the natural habitats of Hyphaene will require a solid collaborative effort with local researchers and collaborators. As indicated ahead in this proposal, we have already made considerable progress in consolidating a reliable network of African researchers around the Hyphaene project. Together we now feel prepared to undertake a multidisciplinary study of this palm group grounded in new collections and observations in the field.
Hyphaene thebaica in Western Djibouti (December, 2015)