What do we know about the Doum palms (Hyphaene spp.)?
Composition and distribution
The genus Hyphaene (apparently 8 spp.) is distributed in dry regions of continental Africa, Madagascar, the Red Sea region, and the coasts of the Gulf of Eilat, Arabia and western India (Dransfield et al. 2008, Stauffer et al., 2014)
An unequivocal fossil of Hyphaene (H. kapelmanii A. D. Pan, B. F. Jacobs, J. Dransf. & W. J. Baker) was described by Pan et al. (2006) from a tuffaceous ironstone deposit of Late Oligocene age (28-27 Mya) in north-western Ethiopia. A petrified palm petiole (Palmocaulon hyphaenoides) showing similarities with the currently recognized H. dichotoma was described by Shete & Kulkarni (1980) from the Indian Deccan Intertrappean of Maharashtra State. Endocarps supposed to be from the earliest Cretaceous (Aptian) of Egypt are compared to Hyphaene by Vaudois-Miéja and Lejal-Nicol (1987), although one endocarp looked notably Hyphaene-like. Nevertheless, an Aptian age for the formation in which these fossils (Hyphaeneocarpon aegyptiacum) were found is questionable and may be much younger (Schrank, 1992; Dransfield et al., 2008).
Ethnobotany and economic botany
As already reported for other African palms, almost all species of Hyphaene, particularly H. thebaica, display a wide range of uses (Figs. 1-2), and this has been thoroughly documented in several ethnobotanical publications (e.g. Burkill, 1997; Diniz & Martins, 2002; Sunderland, 2003; Latham & Konda, 2007; Kahn & Luxereau, 2008; Régis et al., 2008). Hyphaene thebaica was sacred in Egypt (Fig. 1), appearing to have been extremely important both in the ritual and the economy of the pharaohs (Corner, 1966), and by the New Kingdom in particular many basket making and matting techniques using this palm were developed (El Hadidi & Hamdy, 2011; Borojevik & Mountain, 2013).
Fig. 1. Ancient uses of Hyphaene. This well preserved fruits of Hyphaene thebaica (lower-right side of the image) were found in a tomb-chapel that commemorated Nebamun (c 1350 BCE), a middle-ranking official scribe and grain counter. This tomb is located in the Theban Necropolis located on the west bank of the Nile at Thebes (present-day Luxor), in Egypt. Figs and dates can be also seen on the left side of the image. The fruits are displayed in the Egypt permanent exhibition of the British Museum in London.
Most species of Hyphaene currently provide essential resources for rural populations (Fig. 2), ranging from construction materials and food (Figs. 3a-c, Fig. 5), including wine (Fig. 4), to raw materials for thatching, handcrafts, (Fig. 3d), medicines and livestock feed. Petioles and stems are used in construction, and adult stems of H. petersiana are tapped for palm-wine production in Zimbabwe (Sola et al., 2006) and Namibia (Sullivan et al., 1995; Fujioka, 2005; Cheikhyoussef & Embashu, 2013), and H. coriacea similarly in Madagascar (Du Puy & Randrianasolo, 1992). The leaves of H. compressa meet many subsistence and economic needs of the nomadic pastoralist and agro-pastoralist communities in the northern and eastern regions of Kenya (Amwatta, 2004). In East Africa (Djibouti, Sudan, Kenya), West Africa (Nigeria) and South-West Africa (Namibia) the fruits of Hyphaene are regarded as a key source of nutrition during the end of the dry season when food is scarce (Lokuruka, 2007, 2008; Aremu & Fadele, 2011; Cheikhyoussef & Embashu, 2013; Aboshora, 2014; Aberlenc pers. comm. Data on the nutritional composition of the fruits are available for some species (Atchley, 1984; Bonde et al., 1990), and the chemistry of the essential oils from the fruits of H. thebaica were studied by Ayoub et al. (2011). Most pharmacological studies have concentrated on the fruits or leaves of H. thebaica. These have revealed biological activity and antioxidants from organic and aqueous extracts of fruits (Sharaf et al., 1972; Hsu et al., 2006; Farag & Paré, 2013), and antioxidant activity has been reported in aqueous ethanol extracts from leaves (Eldahshan et al., 2008). The bony endosperm of the fruits is used as vegetal ivory in Mozambique (H. compressa) and Namibia (H. petersiana).
As described by Sullivan et al. (1995) and Strohbach (2000) for H. petersiana in Namibia, and similarly observed by us for H. thebaica and H. guineensis in Senegal, Ivory Coast and Ghana, the doum palms meet myriad subsistence and economic needs for African populations. Species of Hyphaene provide a wide range of products that contribute to most aspects of people's livelihoods. Unfortunately, increasing regional population pressures, combined with a trend toward land privatization (as recently observed by us in Senegal) is exacerbating pressure on communal resources, including remaining stands of these essential palms. Non-sustainable harvesting of mature palms could now lead to the total loss of wild populations for some species. More recently, Gruca et al. (2015) listed H. compressa, H. coriacea, H. petersiana and H. thebaica among the most useful palms in African traditional medicine. In particular the widespread H. thebaica was reported to have more than 37 different medicinal uses.
Fig. 2. The palm genus Hyphaene is represented by several multi-purpose species. Large populations in Africa strongly rely on the important resources offered by these palms. This schematic representation proposed by Didier Roguet (Conservatory and Botanic Gardens of Geneva) highlights the different uses that have been identified.
Fig. 3. Economic importance of Hyphaene. A. Fresh fruits of H. thebaica commercialized in a street market, Egypt; B. The edible fleshy mesocarp of H. thebaica is widely consumed in east African countries, Kenya; C. Tea made from the fruit mesocarp of H. thebaica; D. Handicraft made from leaves of H. compressa (Tanzania).
Fig. 4. Palm wine is extracted from different species of Hyphaene (i.e. H. petersiana, H. thebaica). In this figure is depicted palm wine tapping in individuals of Hyphaene thebaica in Djibouti; in this arid country palm wine extraction is a widely spread, highly appreciated practice (December, 2015).
Fig 5. Women in Wester Djibouti, not far from the border with Ethiopia, frequently weave mats and produce baskets with the fibers obtained from the young spear leaves of Hyphaene thebaica.