Orania subdisticha A. P. Keim & J. Dransf., Kew Bulletin 67: 165 (2012)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
New Guineapresent (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A
New Guinea. Endemic to an area close to a road to main Gobe Oil Rig, 91 km NW of Kikori, Erave Distr., Southern Highlands (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A

Habitat

  • Montane forest on karst limestone with numerous cliffs and sinkholes at an altitude about 1050 m above sea level. (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A

Discussion

  • Although the subdistichous leaf arrangement is also observed in Orania dafonsoroensis and O. timikae, O. subdisticha has its inflorescence branched to two orders, whereas O. dafonsoroensis and O. timikae have their inflorescence branched to one order only (i.e. simply branched). As leaf arrangement in Orania may change with maturity, the question arises as to whether O. subdisticha may just be a subdistichous form of O. disticha. We have found that apart from the subdistichous leaves, O. subdisticha differs from O. disticha in several morphological characters. O. subdisticha is a small understorey palm, whereas O. disticha is a robust palm with trunk from 15 to 20 m tall and diam. from 20 to 23 cm. O. subdisticha apparently possesses slender inflorescences and straight rachillae, whereas in O. disticha they are both robust and have conspicuously zigzag rachillae. The fruits are also different in size (as measured by their diam.) - smaller in O. subdisticha (about 4 cm compared to 5.5 - 6 cm in O. disticha). (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A

Conservation

  • Vulnerable (VU D2). Although known only from a single collection, the palm occurs in some abundance in montane forest on rocky limestone slopes unlikely to be used for agriculture. (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A

Etymology

  • Sub-distichous leaf arrangement (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A

Description

  • Small palm. Trunk c. 8 m tall, c. 8 cm diam. (DBH). Leaves 7 in the crown, arranged sub-distichously, c. 300 cm long; leaf-sheath c. 120 cm long, 14 cm wide in the near base, adaxial surface glabrous, abaxial surface with dense red-brown tomentum covering, margins slightly disintegrating into fibres; petiole covered with red-brown tomentum, c. 26 cm long, c. 2 - 2.5 cm diam.; rachis c. 154 cm long, densely covered with redbrown tomentum, c. 2 cm diam.; leaflets elongatelanceolate, regularly arranged leaflets held in one plane, c. 22 on either side, c. 70.5 - 80 cm long, 5 - 5.5 cm wide, distance between 2 leaflets c. 10 cm in middle part of rachis; adaxial surface dark green, midrib robust with red-brown tomentum covering, other ribs slender; abaxial surface densely covered with white indumentum, red-brown tomentum on ribs, margin, midrib and near base, midrib less robust than adaxial surface, other ribs slender but thicker than adaxial. Inflorescence spreading, branching to 2 orders, c. 120 cm long; prophyll unknown; peduncle c. 60 cm long, apparently glabrous; peduncular bract apparently one, woody, persistent, c. 150 cm long; rachis c. 60 cm long, number of first order branches 13, rachillae slender, c. 33 - 50 cm long, straight, not obviously zigzag, bearing 63 - 90 flower clusters, bearing triads up to 15 - 25 cm from base (i.e. triads arranged in the proximal 1=2), the basal c. 1 cm devoid of flowers, triads c. 1 cm distant, rachilla glabrous. Staminate flowers with green petals, remaining characters unknown. Pistillate flowers with calyx of 3 united sepals, c. 2 mm long; corolla with 3 free yellowish green, c. 7 × 5 mm; staminodes 6, c. 1=3 as long as gynoecium, uniform; gynoecium dark-brown, c. 4 - 5 mm long, 4 - 5 mm wide; stigma with 3 lobes. Fruit globose, c. 4 cm diam., red. Embryo unknown. Eophyll unknown. (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A

Materials Examined

  • PAPUA NEW GUINEA. Southern Highlands: Erave Distr., road to main Gobe oil rig, 91 km NW of Kikori, 6°46'45.7"S 143°43'59"E, 26 Nov. 2000, W. J. Baker 1116 (AAU, holotype BO!, K!, L, LAE, NY). (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)A

Bibliography

    A. A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012