Hyphaene guineensis

Hyphaene guineensis Schumach. & Thonn. in H. C. F.Schumacher, Beskr. Guin. Pl.: 445 (1827); Palm. Afr. 30 (1995); Palms 48: 14 (2004); Check-list Pl. Vasc. Gabon: 320 (2006); Strelitzia 22: 172 (2008). –Icon.: Palms 48: 10, 12, 13, 16. (Van Valkenburg & Dransfield, 2004)

Synonyms: Chamaeriphes guineensis (Schumach. & Thonn.) Kuntze; H. depressa Becc.; H. doreyi Furtado; H. gossweileri Furtado; H. luandensis Gossw. (nom. nud.); H. mateba Becc.; H. nephrocarpa Becc.; H. welwitschii Furtado.

Palm solitary, tall, armed, unbranched, pleonanthic, dioecious.

Stem erect, solitary or 2-3 stems apparently growing from the same seed, 3-12 m tall and up to 30-40 (-50) cm in diameter, grey, young individuals often covered with remnant leaf sheaths whereas the aged palms present naked stems and the leaf sheaths leaving conspicuous ring.
 
Leaves (13-) 30-40 per crown, costapalmate, up to 1.8 m long, spirally arranged, green, dark green-bluish, the blade covered with small brown dots becoming darker when the leaf dries; leaf sheath up to 25 cm long, 10-15 cm in width, brown, with a triangular cleft at the base, margins fibrous, armed from the middle with robust, triangular, upward pointing black spines; petiole (0.5-)1-2 m long and 4-6 cm in width, green-yellowish to light orange, covered with a brown-cream indumentum, when present densely present between the petiole spines, slightly channeled or flattened adaxially and abaxially convex, then dorso-ventrally compressed in cross-section, margins armed with robust, triangular, reflexed or upward pointing black spines, 0,8-2 cm long and 0.5-0.8 cm wide at the base, the latter with different shapes and distanced 1-3 cm; costa 45-70 cm long and up to 3 cm wide at the base, strongly recurved, light green, smooth, covered with an light-brown indumentum; leaf blade up to 110 cm long and 80 cm wide, divided at 1/3 of its length into 45-62 (-70) regular, induplicate segments, basal segments 40- 85 cm long, 1.3-2.5 (-3) cm wide, middle segments 80-110 (-125) cm long, (2-)-5-7 cm wide, apical segments up to 0.7-1.2 m long and up to (1-) 4-6 cm wide, each segment single-folded and with a 4 cm long, slightly bifid apex, black interfold filaments up to 48 cm long; brown, light and smooth indumentum at the base of the leaf blade and along the ribs, especially on young leaves, becoming caduceous in old leaves.

Inflorescences interfoliar, unisexual, pistillate and staminate inflorescences barely similar, erect; staminate inflorescence up to 120 cm long, erect then slightly pendulous towards the end of anthesis; prophyll tubular, 36 cm long towards the apex, covered with a brownish indumentum; peduncle 10-30 cm long and 2-3 cm in diameter, elliptical in cross section; peduncular bracts 3, tubular, 45-50 cm long, usually covered with a red-brownish indumentum; peduncle 15-20 cm long and 2-3 cm in diameter, circular in cross section; rachis 50-60 cm long, 1-1.5 cm in diameter, circular in cross-section, covered throughout its length by the peduncular bracts; rachillae (3-) 5-12, catkin-like, up to 25 cm long and 1-1.5 cm in cross-section, sterile part of 20-22 cm, fertile part of 40-50 cm long, 1 cm wide, circular in cross sections, inserted in clusters of 3-5 rachillae emerging from the same point of the main rachis; rachillae bracts 6 mm long, spirally arranged, striate, connate laterally and partially adnate to the rachilla and originating pits, spirally arranged on the rachilla, each pit containing 3 flowers arranged in a cincinnus; pistillate inflorescences 5-6 growing simultaneously, branching to 2 orders, up to 1,1 m long, morphologically similar to the male inflorescence; peduncle  35-50 cm long, 2-3 cm in diameter, circular to elliptical in cross section; prophyll 35 cm long; peduncular bracts 7, up to 42 cm long, tubular, covered with a brown-reddish  indumentum; rachis 0.7-1 m long, (1-) 2-4 cm in diameter, elliptical in cross section; at least one bract attached to the peduncle, 26 cm long, 6 cm wide, covered with a wholly indumentum; rachillae 4-6, solitary, rarely in pairs, alternating in the rachis; sterile part 20-30 cm long, 1 cm wide, adaxially concave, fertile part 16-40 cm de long and 1,1-2 cm in diameter, slightly circular in cross section, with a sterile and pointed apex of1 cm long; each rachilla subtended by a bract  similar to the ones observed in the staminate inflorescence, densely hairy, each pit containing a single flower, larger than the male flower.

Flowers unisexual, 3-merous; staminate flowers borne in a cincinnus of 3 flowers, one flower emerging at a time, arranged in more or less 8 parallel rows, slightly displaying a basipetal anthetic pattern, yellow, scentless, subtended by a minute, membranous bracteole; calyx tubular at the base, lobes 3, acute, elongated; corolla with a stalk-like base, lobes 3, ovate, hooded, valvate, striate; stamens 6, inserted at the base of the corolla, filaments with a swollen base, anthers medifixed, versatile, latrorse to introrse; pistillode 3-lobed, minute. Pistillate flowers 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, with undeveloped and empty anthers; gynoecium globose, carpels 3.

Fruits 1-seeded, 6-7.5 cm in length and 6-7 (-10) cm wide, usually pear-shaped, with two conspicuous protrusions near the base, borne on a well-differentiated pedicel up to 6-8 mm long, basal stigmatic remains; epicarp olive-green in young fruits, red to brown or dark-brown when ripe, smooth, shiny, waxy, often with the presence of small dots; mesocarp fibrous, up to 8 mm thick, sweet; endocarp well developed. Seeds 3.2 cm long, 2.9 cm wide, endosperm white; eophyll linear, lanceolate, plicate.

Hyphaene guineensis grows in coastal lowland regions, especially on sandy soils with superficial groundwater; however, it has never been observed growing in inundated areas. This species is mostly distributed from see level to 300 m.

The palm is distributed in West Africa (Guinée-Bissau, Guinée-Conakry, Ghana and Togo). In spite of extensive field work in Ivory Coast the presence of this palm in this country cannot be confirmed. In Central Africa  it is present in Gabon, the Democratic Republic of Congo and the Central African Republic. It has been also reported for Angola.

This species seems to be relatively well understood from a taxonomical point of view; however, it remained rather poorly known since its first description in 1827 (Furtado, 2004; Van Valkenburg & Dransfield, 2004).

The leaflets were traditionally used in Angola and the Democratic Republic of Congo for making coarse bags for packaging peanuts and oil palm nuts (Van Valkenburg & Dransfield, 2004). In South-East Ghana the wood is used for the frame of houses and the leaves are used to make hats and fans.

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/95317509/0

Fig. 1. Regenerating uneven-aged stand of Hyphaene guineensis in the coastal forest of Gabon (photo: Johan van Valkenburg)

Fig. 2. Tall individuals of Hyphaene guineensis in South-Eastern Ghana.

Fig. 3. Stem fully covered by leaf sheaths and spiny petioles, Gabon (photo: Johan van Valkenburg)

Fig. 4. This palm is apparently issued from two seeds that germinated from the same fruit and produced a tween individual. This situation was commonly observed in South-Eastern Ghana

Fig. 5. Leaf blade and spiny petiole of Hyphaene guineensis. Note the pronounced curvature of the costa (South-Eastern Ghana)

Fig. 6. Detail of leaf blade showing the pronounced curvature of the costa (Gabon). Photo: Johan van Valkenburg

Fig. 7. Male inflorescence at anthetic stage (South-Eastern Ghana)

Fig. 8. Male inflorescence at anthetic stage (South-Eastern Ghana)

Fig. 9. Detail of male flowers at anthesis. Note different stages of development of the flowers (i.e. buds vs. anthetic flowers in almost alternating rows)

Fig. 10. Female inflorescence showing well developed female flower buds (South-Eastern Ghana)

Fig. 11. Detail of female flower buds. Note imbricate scales of the rachillae

Fig. 12. Fruits, outward appearance, cut to show mesocarp, endocarp and endosperm; an old decayed fruits showing endocarp structure/texture (Gabon). Photo: Johan van Valkenburg

Fig. 13. Side view of the typical pear-shaped fruit of H. guineensis in South-Eastern Ghana

Fig. 14. Upper view of the typical pear-shaped fruit of H. guineensis in South-Eastern Ghana. Two small carpels remain sterile and undeveloped.

Fig. 15. Cross section of an unripe fruit showing the fleshy endosperm (South-Eastern Ghana)

Fig. 16. Distribution of Hyphaene guineensis (based on Stauffer et al., 2014)