Orania disticha Burret

Vernacular

Pokengeh (Mekeo-Mapia), tidifa (Kutubu).

Conservation

Near threatened (NT). The palm is known from nine different localities with a wide extent of occurrence but wherever it occurs, the vegetation is subject to extensive logging and disturbance from oil and gas extraction.

General Description

Robust palm. Trunk c. 15 - 20 m tall, c. 20 - 23 cm diam. (dbh). Leaves 7 - 12 in the crown, distichously arranged, c. 4.3 m long; leaf-sheath and petiole c. 1.3 m long, adaxial surface glabrous, abaxial surface with dense red-brown tomentum, margins disintegrating into fibres; petiole densely covered with red-brown tomentum; rachis c. 3 m long, c. 2.5 - 3 cm diam.; leaflets elongate-lanceolate, regularly arranged, held in one plane, distance between 2 leaflets c. 7 - 8 cm, c. 90 - 150 cm long, 6.5 - 7.5 cm wide, adaxial surface glabrous, shining, with possible wax, midrib robust, other ribs less robust but thick; abaxial surface with white indumentum, thin red-brown tomentum on the margin and some of the ribs, midrib robust. Inflorescence spreading, branching to 2 orders, glabrous, robust, c. 1.2 - 1.3 m long; prophyll persistent, c. 30 × 7 cm, disintegrating into fibres when old; peduncle c. 3 cm diam.; peduncular bract one, woody, persistent, c. 1.3 m long, including c. 15 cm acuminate tip, c. 13 cm wide near base, adaxial surface glabrous, abaxial surface with dense redbrown tomentum, splitting in the middle, disintegrating into fibres when old; first order branches c. 56 - 60 cm long, rachillae bract c. 3 - 5 mm long, 10 mm wide; rachillae robust, conspicuously zigzag, c. 41 - 70 cm long each, bearing 65 - 115 flower clusters, triads proximally arranged up to c. half part of rachilla, distally half part of rachilla with paired staminate flowers, the basal c. 1.5 - 3.5 cm devoid of flowers, triads c. 1.5 - 2.3 cm distant, rachilla glabrous. Staminate flowers pale creamy brown; with calyx of 3 united minute sepals; corolla with 3 free petals, c. 13 - 14 mm long, 4 - 5 mm wide; stamens 6, filaments free, dark brown, c. 1.7 - 2.3 mm long, anthers elongate-lanceolate, pale creamy yellow, always free, c. 6.5 - 7 mm long; pistillode absent. Pistillode flowers pale creamy brown; with calyx of 3 united sepals, c. 2 - 3 mm long; corolla with 3 free petals, c. 8 - 12 mmlong, c. 5 - 6 mm wide; staminodes 6, c. 1.3 - 2 mm long; gynoecium dark brown, about 4 × 3 mm; stigma with 3 elongate lobes. Fruit globose or lobed, orange (see Burret 1935), c. 5.5 - 6 cm diam.; epicarp thin, smooth; mesocarp fibrous, c. 3 mm thick; endocarp hard, red brown, c. 1 mm thick; testa very thin, red-brown, covering the endosperm; endosperm homogenous, creamy white, c. 4.5 - 5 cm diam., c. 1.5 cm thick, with hollow inside, c. 2 cm wide. Embryo placed below middle line of seed. Eophyll bifid.

Distribution

In Papua this species is found from the tip of the Bird's Head Peninsula region through Nabire in the central part to somewhere near the Idenburg (now Taritatu) river and the southern part of Papua New Guinea up to the south-central part.

Habitat

Abundant on low ridges of lowland tropical rainforest altitudes about 50 to 100 m and up to margin of primary rainforest in rather higher areas reaching about 810 m above sea level.

Keim, A.P. & Dransfield, J. 2012. Kew Bulletin 67: 127. https://doi.org/10.1007/s12225-012-9356-6

Morphology General Habit

Robust palm

Morphology Trunk

Trunk c. 15 – 20 m tall, c. 20 – 23 cm diam. (dbh)

Morphology Leaves

Leaves 7 – 12 in the crown, distichously arranged, c. 4.3 m long; leaf-sheath and petiole c. 1.3 m long, adaxial surface glabrous, abaxial surface with dense red-brown tomentum, margins disintegrating into fibres; petiole densely covered with red-brown tomentum; rachis c. 3 m long, c. 2.5 – 3 cm diam.; leaflets elongate-lanceolate, regularly arranged, held in one plane, distance between 2 leaflets c. 7 – 8 cm, c. 90 – 150 cm long, 6.5 – 7.5 cm wide, adaxial surface glabrous, shining, with possible wax, midrib robust, other ribs less robust but thick; abaxial surface with white indumentum, thin red-brown tomentum on the margin and some of the ribs, midrib robust Eophyll bifid.

Morphology Reproductive morphology Inflorescences

Inflorescence spreading, branching to 2 orders, glabrous, robust, c. 1.2 – 1.3 m long; prophyll persistent, c. 30 × 7 cm, disintegrating into fibres when old; peduncle c. 3 cm diam.; peduncular bract one, woody, persistent, c. 1.3 m long, including c. 15 cm acuminate tip, c. 13 cm wide near base, adaxial surface glabrous, abaxial surface with dense red-brown tomentum, splitting in the middle, disintegrating into fibres when old; first order branches c. 56 – 60 cm long, rachillae bract c. 3 – 5 mm long, 10 mm wide; rachillae robust, conspicuously zigzag, c. 41 – 70 cm long each, bearing 65 – 115 flower clusters, triads proximally arranged up to c. half part of rachilla, distally half part of rachilla with paired staminate flowers, the basal c. 1.5 – 3.5 cm devoid of flowers, triads c. 1.5 – 2.3 cm distant, rachilla glabrous

Morphology Reproductive morphology Flowers

Staminate flowers pale creamy brown; with calyx of 3 united minute sepals; corolla with 3 free petals, c. 13 – 14 mm long, 4 – 5 mm wide; stamens 6, filaments free, dark brown, c. 1.7 – 2.3 mm long, anthers elongate-lanceolate, pale creamy yellow, always free, c. 6.5 – 7 mm long; pistillode absent

Morphology Reproductive morphology Flowers Gynoecium Pistillodes

Pistillode flowers pale creamy brown; with calyx of 3 united sepals, c. 2 – 3 mm long; corolla with 3 free petals, c. 8 – 12 mm long, c. 5 – 6 mm wide; staminodes 6, c. 1.3 – 2 mm long; gynoecium dark brown, about 4 × 3 mm; stigma with 3 elongate lobes

Morphology Reproductive morphology Fruits

Fruit globose or lobed, orange (see Burret 1935), c. 5.5 – 6 cm diam.; epicarp thin, smooth; mesocarp fibrous, c. 3 mm thick; endocarp hard, red brown, c. 1 mm thick; testa very thin, red-brown, covering the endosperm; endosperm homogenous, creamy white, c. 4.5 – 5 cm diam., c. 1.5 cm thick, with hollow inside, c. 2 cm wide

Morphology Reproductive morphology Seeds Embryo

Embryo placed below middle line of seed

Distribution

In Papua this species is found from the tip of the Bird’s Head Peninsula region through Nabire in the central part to somewhere near the Idenburg (now Taritatu) river and the southern part of Papua New Guinea up to the south-central part. Map 6.

Ecology

Abundant on low ridges of lowland tropical rainforest altitudes about 50 to 100 m and up to margin of primary rainforest in rather higher areas reaching about 810 m above sea level.

Conservation

Near threatened (NT). The palm is known from nine different localities with a wide extent of occurrence but wherever it occurs, the vegetation is subject to extensive logging and disturbance from oil and gas extraction.

Note

Distichous appearance. In the most recent monograph of the genus (Essig 1980), Orania disticha was the only New Guinean species known to have its leaves arranged distichously. In the present study, we describe another distichous species, O. tabubilensis. Apart from the distichous leaves, O. disticha is very similar to O. palindan. However, we regard distichy as sufficiently important to recognise O. disticha as a species based on recent fieldwork in New Guinea by Baker (2000 pers. comm.) and Maturbongs (2001 pers. comm.). They reported that the distichous leaf arrangement persists in mature individuals found in Madang, Papua New Guinea (Baker 2000 pers. comm.) and Kwatisore-Nabire, Papua (Maturbongs 2001 pers. comm.). Unfortunately, Baker only saw the population from the air on his way to other collecting areas. However, Maturbongs provided us with a good collection. In 2002 Maturbongs collected another specimen of distichous Orania from a different location in Papua, Warsamson area, which is north-east of Sorong in the Bird’s Head Peninsula. They match the descriptions of O. disticha.

A claim for another distichous taxon found in New Guinea was proposed by Ferrero (1997). He reported the presence of an individual with a distichous leaf arrangement and colourful leaves in Papua without giving any details of the exact location and suggested it as a new species. In fact the leaf of O. disticha is indeed densely covered with red-brown tomentum and actually in the protologue Burret (1935) clearly noted this. It is the inflorescence, which is glabrous, not the leaf. In this present study it is suggested that until more evidence becomes available, Ferrero’s record is best treated as possibly belonging to O. disticha. The observations on herbarium specimens carried out in this study also agree with the protologue. The other distichous taxa are in Madagascar. Essig (1980) in his monograph wrote that Burret did not designate a holotype and with the Berlin specimen destroyed, Essig selected the specimen in A as lectotype.

Vernacular

pokengeh (Mekeo-Mapia), tidifa (Kutubu).

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/189113015/206088452

Conservation

LC - least concern

Use

Leaves are used for thatching.