Hyphaene thebaica

Hyphaene thebaica (L.) Mart., Hist. Nat. Palm. 3: 226 (1838); Fl. W. Trop. Afr., ed. 2 3(1): 169 (1968); Palm. Afr. 28 (1995); Fl. Ethiopia & Eritrea 6: 522 (1997); Fl. Egypt (Boulos) 3: 104 (2002); Fl. anal. Bénin: 58 (2006); Boissiera 55: 33 (2012). – Icon.: Palm. Afr. 151, 152 (1995); Palms 52: 23-27 (2008).

Type: Palma thebaica Pococke, A Description of the East, and Other Countries 1: 281, pl. 73. 1743 (lectotype designated by Moore and Dransfield, 1979). See taxonomic note below and Fig. 1.

Synonyms: Chamaeriphes crinita (Gaertn.) Kuntze; C. thebaica (L.) Kuntze; Corypha thebaica L.; Cucifera thebaica (L.) Delile; Douma thebaica (L.) Poir.; H. baikieana Furtado; H. crinita Gaertn.; H. cuciphera Pers.; H. dahomeensis Becc.; H. dankaliensis Becc.; H. nodularia Becc.; H. occidentalis Becc.; H. santoana Furtado; H. sinaitica Furtado; H. togoensis Dammer ex Becc.; H. tuleyana Furtado; Palma thebaica (L.) Jacq.

Palm solitary or forming clumps of (3-)5-7 stems almost emerging from the same point and at different stages of development, armed, pleonanthic, dioecious.

Stem (3-)8-15 m in height and 30-45 cm in diameter, branched to 1-4-order dichotomies (Figs. 1-2), with the first one appearing (1.7-)2.5-4(-6) m above ground, producing up to 16 leaf crowns; the stem covered or not with remnant leaf sheaths which fall off in aged individuals, grey, leaving conspicuous, 1-3 cm thick ring scars when young, then the scars becoming closer in older individuals (Figs. 2-3).

Leaves (8-)10-18 (-25) per crown, costapalmate, spirally arranged, dark green to bluish; leaf sheath 24-30 cm long, 16-20 cm wide, grey-brown, with a triangular cleft at the base, often remaining below the leaf crown or throughout the length of the stem in young individuals, margins fibrous, armed from the mid-length with robust, triangular, upward pointing black spines; petiole (0.5-) 1-2 m long, (2-) 5-10 cm wide at the base and 3-4 cm at mid-length, green-grey to black, at the base adaxially channelled and abaxially rounded, towards the apex dorso-ventrally compressed in cross-section, margins armed with robust, triangular, reflexed or upward pointing black spines, up to 2 cm long and 0.8-1 cm wide at the base, displaying different shapes; hastula 1.5- 6 cm long, green, with slightly black margins; costa (30-) 40-60 cm long and 1.5-2.2 cm in width, light green, smooth, conspicuously recurved, triangular in cross-section; leaf blade olive-green, 1-2 m long, showing small brown dots becoming darker when the leaf dries, divided at 1/3 of its length into (32-)50-60 regular segments, main veins prominent on the abaxial side, basal segments 30-50(-70) cm long and 1.5- 2.5(-4) cm wide, middle segments 50-60 (-90) cm long and (2.5-) 5-7 cm wide, apical segments 35-50(-60) cm long and 1.5-4.5(-6) cm wide, single-folded, with a slightly bifid apex up to 4-7 cm long, presence of interfold filaments between segments of up to 60 cm long, a brown, light and smooth indumentum present at the base of the leaf blade and encompassing the mid veins, especially on young leaves, and becoming caduceus on aged leaves.

Inflorescences unisexual, interfoliar, pistillate and staminate inflorescences similar. Staminate inflorescence 1-branched, 5-6 on the same individual, 1.2-2 m long, digitate, erect at juvenile stage and becoming pendent at anthesis; peduncle (20-)30-50 cm long and (1.5-)3-4 cm, dorsoventrally compressed; prophyll tubular, eventually appearing dorso-ventrally compressed, opening apically as a lanceolate projection; peduncular bracts up to 16, basal bracts 28-30 cm long and 4-5 cm wide, medial bracts 12-15 cm long and 3-4 cm wide, apical bracts 6-10 cm long and 1-2 cm wide; rachis 30-60 cm long, 1.5-2 cm wide; rachillae (2-) 4-6, catkin-like (ending in 4 apical segments), up to 45 cm long, sterile part of 27 cm and the fertile one up to 17 cm long; rachillae bracts 7-8 mm long and 2-3 mm wide, spirally arranged, striate, connate laterally and partially adnate to the rachilla, subtending pits containing 3 flowers arranged in a cincinnus. Pistillate inflorescence 1-branched, 5 on the same individual, (0.4-) 1-15 m long, peduncle 17-45 cm long, 1-1,5 cm in diameter, prophyll 20-25 cm long, apically opening with two longitudinal slits, coriaceous, brown, with a spongy indumentum towards the apex, peduncular bracts 3-5, smooth, similar to the prophyll, rachis 40-48(-60) cm long, rachillae 5-8, catkin-like (ending in 3-5 apical segments); basal rachillae with a sterile part of 19 cm and a fertile part of 20 cm, middle rachillae with a sterile part of 20 cm and a fertile part of 20-21 cm, apical rachillae with a sterile part of 20 cm and a fertile part of 23 cm; rachillae bracts resembling the ones of the male inflorescence, densely hairy, each pit containing a single flower, clearly larger than the male flower.

Flowers unisexual, 3-merous. Staminate flowers borne in a cincinnus of 3 flowers, one flower emerging at a time, subtended by a minute, membranous, green bracteole; calyx basally tubular, apically with 3 acute, elongated lobes; corolla with a stalk-like base, valvate, lobes 3, ovate, hooded, striate; stamens 6, connate at the base to the corolla, filaments with a swollen base, anthers medifixed, versatile, latrorse to introrse; pistillode 3-lobed, minute. Pistillate flowers larger than staminate, borne solitary in each pit, subtended by a membranous bracteole, supported by a short, thick, densely hairy pedicel; sepals 3, distinct, triangular-rounded, imbricate, striate; petals 3, similar to the sepals but more flexible; staminodes 6, fused in an epipetalous ring, sagittated, flattened, anthers undifferentiated; gynoecium globose, 3-carpellate, 3-ovulated but only reaching maturity.

Fruits 1-seeded (Fig. 4), (4-) 5-6 cm  long, 4-5 cm in wide, highly variable in shape and size (shouldered, asymmetrical, oblong-ovoid, obovoid, rarely ovoid, usually pear-shaped), borne on a 6-8 mm long pedicel, basal stigmatic remains; epicarp ranging from orange, red to brown or dark-brown in ripe fruits, smooth, shiny, waxy, often presence of small dots; reduced sterile carpels (1-2) usually visible towards the base of the fruit; mesocarp conspicuously fibrous, up to 8 mm thick, sweet; endocarp well developed. Seeds as diversely shaped as the fruits, basally attached, endosperm white, with a coconut flavour when young, with a central hollow cavity when ripe; germination remote-tubular, cotyledonary petiole buried up to 80 cm underground; eophyll linear-lanceolate, plicate.

This is a palm of arid, desert climates, associated with the heavy soils of drainage lines and alluvial flats with high water tables.

The distribution of H. thebaica is rather complex due to the fact that the species is economically important and has traditionally been planted by human populations. It has been reported for the Sahel region (Burkina Faso, Mali, Niger, Tchad) and also in tropical West African countries (northern Côte d’Ivoire, Ghana and Senegal). This palm is also present in Cameroon, Somalia, Sudan, Ethiopia (Tuley, 1995; Arbonier, 2009, Hedberg, et al., 2009; Darbyshire et al., 2014); its presence in Angola needs to be confirmed (Baker, 2008).The species has been also reported in Madagascar (Dransfield and Beentje (1995) and in the Red Sea region, and the coasts of the Gulf of Eilat, Arabia (Dransfield et al., 2008) (Fig. 5).

Possible hybridization of this species with other taxa of Hyphaene has been reported by several authors and observed by us in the Botanical Garden of the University of Accra (Ghana).

In some West African countries (e.g. Ghana, Mali, Nigeria) the petiole and the leaf blade are used for the elaboration of baskets hats and fans. The stems, in particular those from male individuals, are sold as timber due to its recognized resistance to insects. The fruits are known to be occasionally eaten. A detailed description on the leaf collecting practices in this species was carried out by Kahn and Luxereau (2008). For a comprehensive description of the uses of this palm in West tropical Africa see Burkill (1997).

The conservation status of this species has been recently assessed by Cosiaux et al. (2017) and the category of Least Concern (LC) has been proposed. You can get detailed information on this assessment by clicking in the following link: http://www.iucnredlist.org/details/19017230/0

Taxonomic note: In the absence of any known original specimen associate to the Linnaean herbarium Moore and Dransfield (1979) chose the plates 72 and 73 of Pococke’s publication as lectotype of the species.  Linnaeus original description in the Species Plantarum (Linnaeus, 1753) only cites the copperplate 73.  The observations of Richard Pococke (1704-1765) were made in Egypt, which corresponds to a part of the wild distribution of the species and the two plates perfectly depict the main features diagnostic for the palm. The original typyfication proposed by Moore and Dransfield (1979) was confirmed by Jarvis (2007), with the precision that only plate 73 should be retained as original material.

Fig. 1. Plates 72 and 73 appeared in Pococke’s (1743) publication. The plates 72 (A: left image) and 73 (B: right image) where chosen by Moore and Dransfield (1979) as lectotypes of the species. As Linnaeus (1753) only cited plate 73 this is the one that should be truly regarded as the lectotype of Hyphaene thebaica.

Fig. 2. Stand of Hyphaene thebaica in the locality of Saouga, North of Burkina Faso, in the Sahelian region Photo: Amadé Ouédraogo, University of Ouagadougou (September, 2015).

 Fig. 3. Typical growth habit of Hyphaene thebaica in Western Djibouti

Fig. 4. In Hyphaene thebaica usually many infructescences are present on the same individual, giving a very informative picture on their development. The seed of this palm cultivated in the Montgomery Botanical Center (Miami, USA) was collected in the West African country of Burkina Faso.

 Fig. 5. Distribution of Hyphaene thebaica (based on Stauffer et al., 2014)