Orania Zipp., Alg. Konst- Lett.-Bode 1: 297 (1829)

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Introduction

  • The subject of this monograph is Orania Zipp., a genus of single stemmed pinnate leaved monoecious tree palms with 28 species. The genus has an interesting disjunct distribution, with 25 species in Malesia and three species confined to Madagascar. There has been no recent monograph since that of Essig (1980), yet many new collections have been made and thus the genus now needs substantial revision. With the presence of triads and reduplicate pinnate leaves, Orania is unmistakably a member of the subfamily Arecoideae (Dransfield et al. 2008). (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)

Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)

About 25 species distributed in south Thailand, Malay Peninsula, Sumatra, Java, Borneo, Philippines, Sulawesi, Moluccas and New Guinea, and three species in Madagascar. The greatest diversity occurs in New Guinea, with a minor radiation in the Philippines. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)

Habitat

  • Twenty-five of the 28 species of Orania are found within Malesia. Only one of those species, O. sylvicola (Griff.) H. E. Moore, penetrates into a small, restricted area beyond the border with the Indochinese floristic region (southern part of Thailand). The other three species are distributed in Madagascar (Baker et al. 1998). In Malesia Orania is found in almost every part of the floristic region from the southern part of Thailand to the Malay Peninsula, Sumatra, Java (western part only), Borneo, the Philippines, possibly in Sulawesi (Celebes), the Moluccas and mainland New Guinea including the small nearby islands offshore in Milne Bay in the southeast (D'Entrecasteaux Islands). The centre of diversity is in New Guinea, both in Papua and Papua New Guinea, where 22 species have been recognised in this study. Nineteen of those 22 species are endemic to mainland New Guinea. The three other species (O. lauterbachiana, O. palindan Merr. and O. regalis) have extra-New Guinean distributions.
    Orania palindan is known to have been collected or seen in the Moluccas, Celebes (Beckwith 1940 pers. not. in Fairchild 1943) and the Philippines, so is the most widespread species in the genus. O. lauterbachiana has been collected from the D? Entrecasteaux Islands as well as from mainland New Guinea. O. regalis has also been collected in the Aru Archipelago. The genus has never been collected east of mainland New Guinea and the D'Entrecasteaux Islands.
    In Madagascar Orania is known from forest areas in the eastern and north-eastern areas and a small enclave in the north-western area. Three species have been recognised: O. longisquama (Jum.) J. Dransf. & N. W. Uhl, O. ravaka Beentje and O. trispatha (J. Dransf. & N. W. Uhl) Beentje & J. Dransf. O. longisquama is widespread, whereas the two other species are found only in the eastern and north-eastern areas. The only species reported from the islands surrounding Madagascar is O. ravaka known from Île Sainte Marie (Dransfield & Beentje 1995).
    In both Malesia and Madagascar Orania occupies a great variety of habitats from lowland coastal swampy heath forest about 10 m above sea level to highland tropical humid rainforest about 1220 m above sea level. It also occurs on a wide range of soil types.
    (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)

Discussion

  • Orania is of considerable interest. Not only does it have an astonishingly disjunct distribution but the inflorescence and flowers are rather unspecialised within the Areceae. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)
  • Unfortunately, despite its easily recognised appearance, widespread and interesting disjunct distribution and traditionally important uses, Orania has long been one of the least known and most poorly understood members of the Arecoideae.
    One difficulty faced by previous workers on Orania was sorting out the nomenclature (i.e. typification) for some of the species. This was presumably due to limited access to type specimens, mainly because some of them have been lost. Furthermore, many collections are incomplete, resulting in doubtful species delimitation. In this study we have had type specimens from various herbaria available. We have also had access to more herbarium specimens than previous workers and have conducted extensive fieldwork and have therefore been able to make more complete morphological observations.
    The greatest difficulty in the area of biogeography is the problem of under-collecting. Little collecting of Orania has been done in the eastern part of Indonesia including the Moluccas and Papua. Although there is photographic evidence of Orania in Sulawesi (Beckwith 1940 pers. not. in Fairchild 1943), no collection has ever been made. We have had the advantage of being able to make new collections of Orania in Papua without facing many of the difficulties encountered by previous workers. The results of this fieldwork give new data on the distribution, variation within species in the wild and relationships among the species. This has led to a complete change in the way we look at the distribution of the genus, especially in Malesia.
    Finally, all of these factors have provided a basis for an improved working taxonomy and biogeography of the genus.
    (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)

Diagnosis

Biology And Ecology

Etymology

Uses

  • Outer part of the trunk is reputed to be strong and has been used to make spears. The ‘cabbage’ of all species seems to be poisonous and avoided by local people; Orania sylvicola is reputed to be very poisonous in all its parts. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)
  • So far Orania has never been recorded to have any important economic or commercial value except for its potential ornamental use. Traditionally, however, it has been used by people in many places throughout Malesia and Madagascar for many purposes related to their everyday needs. The trunk is used for building materials in Sumatra, Malay Peninsula and Java (Mogea 1991). Similarly, in Madagascar the wood is also used for house walls and hut construction (Dransfield & Beentje 1995). In New Guinea Orania is more important than in other parts of Malesia and Madagascar. Besides the similar use of wood, the leaves are used for house thatching and the outer wood is commonly used in making arrows and arrowheads (Powell 1976; Zona 1995 pers. comm.).
    Although the cabbage and fruit are believed to be poisonous and have never been recorded as normally consumed, their lethality, as mentioned by Burkill (1935) is likely to be just a myth. A person once ate the fruit of Orania regalis planted in Bogor Botanical Garden and had stomach uneasiness and dizziness in the night but soon recovered on the following day. The people of Siwi-Ransiki (Papua) said that the fruit of O. palindan tastes bitter and is frequently consumed by wild pigs without killing either the people or animals. Dransfield & Beentje (1995) reported that Beentje drank some fruit sap of O. longisquama without any ill effects.
    (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)

Description

  • Small to large, solitary, unarmed, pleonanthic, monoecious palms. Stem erect, short to tall, becoming bare, conspicuously ringed with leaf scars, and sometimes bearing corky, warty protuberances. Leaves distichous (Orania disticha, O. ravaka, O. trispatha and sometimes O. lauterbachiana) or spirally arranged, large, pinnate, deciduous under their own weight; crownshaft not present; sheath well developed, splitting longitudinally opposite the petiole, usually densely tomentose, distally narrowing into the petiole; petiole usually relatively short, channelled adaxially, rounded abaxially, bearing abundant persistent or caducous tomentum; rachis much longer than the petiole; leaflets single-fold, regularly arranged and held ± in one plane, or rarely (O. archboldiana) grouped and held in several planes giving the leaf a plumose appearance, linear-lanceolate, often narrow, frequently somewhat plicate, apices praemorse, adaxial surface glabrous, dark green, abaxial surface covered with dense white indumentum and rarely with brown ramenta along the mainvein (Madagascar species), midrib very prominent adaxially, transverse veinlets obscure. Inflorescences axillary, interfoliar, solitary, often massive, branching to 1–3 orders, protandrous; prophyll short, tubular, 2-keeled, included within the subtending leaf, usually becoming frayed distally; peduncular bracts usually 1, rarely 2, borne just above the prophyll, very large and conspicuous, almost woody, tubular, completely enclosing the inflorescence in bud, before anthesis splitting along their length to expose the inflorescence, eventually deciduous, apically with a solid flattened, lanceolate beak, and bearing sparse to abundant tomentum, often grooved on drying; peduncle ± circular in cross-section, short to very long, variously tomentose; subsequent first-order bracts very inconspicuous except rarely in O. oreophila where well developed in one collection; rachis shorter or longer than the peduncle; first-order branches often with a basal pulvinus; further branches, where present, each subtended by an inconspicuous triangular bract; rachillae usually spreading, flexuous, (in O. regalis congested), glabrous or variously tomentose, bearing rather distant triads proximally and solitary or paired staminate flowers distally, more rarely with triads almost throughout, or with staminate flowers throughout; triads subdistichous or spirally arranged, ± superficial, subtended by a minute triangular rachilla bract; floral bracteoles minute or not visible. Staminate and pistillate flowers superficially rather similar, cream-coloured. Staminate flowers narrower and longer than the pistillate; calyx very short, flattened, with 3, low triangular lobes or with 3 distinct imbricate lobes; petals 3, distinct, valvate, broad to narrow-lanceolate, ± striate in dried state; stamens 3, 4, 6 or 9–32, filaments distinct or variously connate, short to moderate, rather fleshy, anthers elongate, basifixed, erect, with large connective, extrorse, or latrorse; pistillode usually lacking, minute and trilobed in O. palindan, sometimes present in O. sylvicola (minute, conical). Pollen ellipsoidal, slight or obvious asymmetry; aperture a distal sulcus; ectexine tectate, finely perforate, perforate and micro-channelled, or perforate-rugulate, aperture margin broad, psilate-perforate; infratectum columellate; longest axis ranging from 23–40 µm (Thankaimoni 1970) [2/25]. Pistillate flowers ± conical or pyramidal; calyx flattened, very short, with 3 low, triangular lobes or with 3 distinct imbricate sepals; petals 3, distinct, valvate, triangular; staminodes 3–11, very short, awl-shaped, or well developed, possibly rarely producing pollen (some collections of O. sylvicola); gynoecium trilocular, triovulate, ± pyramidal, stigmas 3, short, recurved at anthesis, ovule form unknown. Fruit developing from 1, 2, or rarely 3 carpels, orange, green, or dull orange to yellowish-brown at maturity, spherical or very slightly pear- shaped, where more than 1 carpel developing, each lobe spherical, stigmatic remains subbasal; epicarp smooth, mesocarp thin or thick, fleshy, traversed by numerous short radial fibres, endocarp rather thin. Seed spherical, basally attached with a ± circular hilum, the surface of the seed somewhat grooved by a sparse network of fibres, endosperm homogeneous, sometimes with a very small central hollow; embryo subapical or lateral. Germination remote-tubular; eophyll bifid with praemorse apices, or rarely pinnate. Cytology: 2n = 32. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)
  • Habit solitary, pleonanthic, monoecious palms of the forest understorey and canopy. Stems varying in height, often conspicuously ringed with leaf scars, sometimes with wax. Leaves massive in many species, almost always spirally arranged, rarely distichous or subdistichous, reduplicately pinnate and deciduous under their own weight; crownshaft absent; sheath well developed, thick and woody, splitting longitudinally opposite the petiole, usually densely tomentose, fibrous along the margins; petiole usually short, channelled adaxially, rounded abaxially; rachis much longer than the petiole, curved, abaxially rounded, adaxially angled but channelled near the base; leaf-sheath and ligule
    usually disintegrating into fibres. Leaflets single-fold, regularly arranged and held in one plane except in three species, O. archboldiana, O. deflexa and O. tabubilensis where the leaflets held in more than one plane giving the whole leaf a plumose appearance, apices praemorse; adaxial surface bright green when mature, glabrous, sometimes with conspicuous wax, abaxial surface densely covered with white indumentum, in Madagascar species usually with ramenta along the main vein, ramenta absent in Malesian species, midrib prominent adaxially; marginal nerves occasionally prominent, transverse veinlets obscure or occasionally conspicuous. Inflorescence axillary, solitary, interfoliar, protandrous, almost all spreading, rarely congested, branched from 1 to 3 orders, most species to 2 orders; peduncle stout, circular in cross-section, covered in caducous brown scales, sometimes greatly elongate to two times or more length of rachis; prophyll persistent, short, tubular, 2-keeled, included within the subtending leaf, usually becoming frayed distally; peduncular bract one; or in Madagascar species sometimes two, borne just above the prophyll, very large and conspicuous, almost woody, tubular, often inflated, completely enclosing the inflorescence
    in bud, splitting along its length to expose the inflorescence, with a solid, flattened, lanceolate beak, tomentose, eventually deciduous; rachis usually longer than peduncle, brown tomentose and bearing spirally arranged low glabrous, coriaceous, collar-like bracts subtending first-order branches; first-order bearing few, spirally arranged, similar bracts, each subtending 2nd order branch; first-order branches often with a basal pulvinus; further branches subtended by an inconspicuous triangular bract; rachillae spreading, flexuous, bearing rather distant triads proximally and solitary or paired staminate flowers distally; triads superficial, subtended by a minute, scale-like triangular rachilla bract, or rachilla bracts sometimes absent; floral bracteoles minute, scale-like or sometimes absent. Flowers superficially rather similar, creamcoloured, borne in triads in up to half length of rachilla, the rest in dyads, most species with 20 to more than 100 flower clusters per rachilla. Staminate flowers asymmetrical, narrower than the pistillate; sepals 3, almost distinct or more usually united partly; petals 3, fleshy, distinct, valvate, thickened at the apex, lanceolate-elongate or somewhat spatulate; stamens 3 -14 in Malesian species, 16 - 42 in Madagascar
    species; filaments dark brown, short to moderate, rather fleshy, distinct or wholly or partially united; anthers creamy pale yellow, lanceolate-elongate, basifixed, erect, with large connective, extrose or latrose, free, occasionally united; pollen elliptic or circular, monosulcate, with fine reticulate or rugulate, tectate or semi-tectate exine; pistillode absent, rarely obvious in O. longistaminodia. Pistillate flowers regularly or slightly irregularly arranged, conical or pyramidal;
    calyx flattened, short, basally tubular with 3 low, triangular lobes; petals 3, valvate, distinct, triangular; staminodes usually creamy pale yellow, mostly 3 - 6 (-10) in Malesian species, 11 to more than 20 in Madagascar species, very short, awl shaped or welldeveloped, in most species uniform in size and shape; gynoecium dark brown, triloculate-triovulate, pyramidal; stigmas 3, short, recurved at anthesis; ovule laterally attached, pendulous, presumably hemianatropous. Fruit green in juvenile, greenish yellow or bright reddish orange when mature, developing from 1, 2 or 3 carpels, rounded bi-, or tri-lobed; spherical or globose in one lobed form, rarely obovoid or sub-pyriform; stigmatic remains sub-basal; epicarp smooth, very thin; mesocarp fleshy, traversed by numerous short radial fibres; endocarp dark brown, thinner than mesocarp, with deeply grooved surface, heart-shaped button present basally; testa very thin, dark brown, attached to seed, with grooved surface. Seed spherical, basally attached with a circular hilum, surface somewhat grooved by a sparse network of fibres, endosperm homogenous, sometimes with hollow; clear liquid
    endosperm present up to maturity, embryo sub-apical or lateral. Germination remote-tubular. Eophyll bifid with praemorse apices, or pinnate. Cytology based on study by Eichhorn 1957, n = 16 (O. sylvicola as O. macrocladus, O. palindan as O. philippinensis); for other species unknown. (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)

Relationships

  • Orania is monophyletic with high support (Lewis and Doyle 2002, Asmussen et al. 2006, Baker et al. in review). For relationships, see tribe Oranieae. (J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008)
  • Drude (1887) included Orania in his subfamily Ceroxylinae. Orania together with Arenga Labill., Caryota L. and Wallichia Roxb. were included in the subtribe Caryoteae [sic.]. However, Drude did not mention the obvious difference in leaflet plication among the genera he included in the same subtribe, reduplicate in Orania and induplicate in the others. Beccari & Pichi Sermolli (1955) were the first to propose the tribe Oranieae Becc., but in their concept the tribe
    also included Sclerosperma G. Mann & H. Wendl. and Ravenea H. Wendl. ex C. D. Bouché. Based on pollen data, Sowunmi (1972) excluded the two genera from Oranieae and suggested separate tribes for each of them. Sowunmi suggested the tribe should be monotypic. There was no mention of Sindroa Jum., and Halmoorea J. Dransf. & N. W. Uhl had not yet been proposed.
    In the first edition of Genera Palmarum (GP1), Uhl & Dransfield (1987) placed Orania (including Sindroa) together with Halmoorea in subtribe Oraniinae J. Dransf. & N. W. Uhl within the tribe Areceae. Later Dransfield & Beentje (1995) included the genus Halmoorea in Orania thus leaving Orania as the only genus in the subtribe. Uhl & Dransfield mentioned that the inclusion of Oraniinae together with the other three subtribes with triovulate-triloculate gynoecia (Manicariinae J. Dransf.&N.W. Uhl, Leopoldiniinae J. Dransf. & N. W. Uhl and Malortieinae Benth. & Hook. f.) in Areceae was problematic. However, at the time there seemed to be no better placement for these anomalous taxa (Uhl & Dransfield 1999). Henderson (1990) suggested two possible affinities for the then subtribe Oraniinae, either with the subtribe Wettiniinae Benth. & Hook. f. (tribe Iriarteeae Drude) or the monogeneric tribe Podococceae J. Dransf. & N. W. Uhl.
    Uhl et al. (1995) were the first after GP1 to indicate that the genus might not be a member of tribe Areceae. The result of their study shows that Orania is in the same clade as Podococcus G. Mann & H. Wendl., which according to GP1 is not a member of Areceae. Orania is separated from the other members of Areceae except for Manicaria Gaertn. Manicaria is a member of one of the problematic subtribes within Areceae, Manicariinae (Uhl & Dransfield 1987).
    In the most recent phylogenetic classification of the palm family based on molecular and morphological data, Orania is treated as the sole member of the tribe Oranieae (Dransfield et al. 2005, 2008). Unlike the classification of Beccari & Pichi Sermolli (1955), in this recent classification the genera Sclerosperma and Ravenea H. Wendl. ex C. D. Bouché are excluded from Oranieae. Sclerosperma is placed in its own tribe, Sclerospermeae, whereas Ravenea belongs in tribe Ceroxyleae within a completely different subfamily (Ceroxyloideae). (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)

Taxonomic accounts

  • The first use of the generic name Orania was in a letter by Zippelius dated 1823 to Blume (Zippelius 1828a) which was later published in Algemeen Konst- en Letter- Bode 1: 297 in 1829. Zippelius also sent the same letter to Tausch in Germany (Zippelius 1828b) where it was later included in Flora oder Botanische Zeitung Regensburg (Flora) 12, also published in 1829. However, Blume's publication has priority. Zippelius saw the first species from the new genus in Triton Bay (Papua) and named it Orania regalis. The generic name Orania itself commemorates F. G. L. Willem van Nassau, Prince of Orange and Crown Prince of the Netherlands (1792 - 1849) (Backer 1936). A picture of O. regalis (as Arausiaca excelsa, picture number 122) published by Blume (1836), which according to him was drawn based on Zippelius's original field notes (now lost), is selected as the type.
    Arausiaca Blume (1836, pictures 119 & 112), comprising one species only, A. excelsa, in New Guinea and Macrocladus Griff. (Griffith 1845), also comprising one species only, M. sylvicola, in Western Malesia (Malay Peninsula to Sumatra and Java), were described at about the same time. However, in 1849 Carl von Martius included Macrocladus Griff. in Orania and Miquel (1859) included Arausiaca Blume in Orania.
    Beccari suggested Orania beccarii F. M. Bailey indicated the presence of Orania in Australia based on specimens sent to him by Bailey (1909), noting, however, several characters not shared with the rest of Orania and he thus named a distinct subgenus, Oraniopsis, with O. beccarii as the only member (Beccari & Pichi-Sermolli 1955). Later this species was treated as a synonym of Orania appendiculata (F. M. Bailey) Domin (Domin 1915). O. appendiculata was later excluded from Orania and put in the completely unrelated genus Oraniopsis (Dransfield et al. 1985). Based on its morphological characters this species belongs to the completely different subfamily, Ceroxyloideae. This ended the 75 year division of Orania into two subgenera and also showed that there is no Orania living in the wild in present day Australia.
    Although Beccari is known to have conducted several botanical explorations in East Malesia, including Moluccas and New Guinea (Beccari 1877, 1905, 1915; Van Steenis 1950), he did not make as many collections of Orania there as botanists prior to him did from West Malesia, kept in BO and FI. This is reflected in his more detailed descriptions of taxa (both species and varieties) that occur in West Malesia compared to Moluccas and New Guinea. Beccari described only four taxa of Orania from East Malesia (O. aruensis, O. lauterbachiana, O. micrantha and O. moluccana) compared to seven in West Malesia. The other New Guinean taxa known to Beccari (O. macropetala K. Schum. & Lauterb. and O. regalis) had already been described previously by other botanists.
    Burret described all of his species of Orania (O. archboldiana, O. brassii, O. clemensiae and O. disticha) based on herbarium specimens sent to him by other botanists who worked in New Guinea, such as L. J. Brass, M. S. Clemens, K. A. Lauterbach and K. Schumann. Burret had more New Guinean specimens available to him and this is reflected in the greater number of species from New Guinea he described (four) compared to Beccari (two). However, Burret is notorious for his narrow species concept.
    Jumelle (1933) published the genus Sindroa with one species. Thanikaimoni (1970) grouped Orania and Sindroa together based on the similarity of their pollen type (which is monosulcate with tectate exine) into his first of 27 pollen types. However, he still recognised them as two distinct genera. Sindroa was later shown by Dransfield & Uhl (1984) to be synonymous with Orania. In the same publication Dransfield & Uhl also described a new genus related to Orania found in Madagascar, Halmoorea, with only one species H. trispatha. Dransfield & Beentje (1995) later included Halmoorea as a synonym of Orania based on much more extensive material.
    The last synopsis of the genus prior to this study was published by Essig in 1980; however, in this synopsis Essig still mentioned only 16 species, 15 in Malesia and one in Australia (Orania appendiculata). He described four new species from Papua New Guinea. Three species (O. brassii, O. clemensiae and O. micrantha respectively) were lumped into O. lauterbachiana. The presence of Orania in Madagascar had not been recognised at the time of Essig's study. Essig conducted more botanical explorations than either Beccari or Burret, particularly in the eastern part of New Guinea (Papua New Guinea). This is reflected in the increased number of species in his synopsis of the genus. Some of the New Guinean taxa described by Beccari and Burret were placed by Essig as synonyms of other species, based on his assessments of the level of morphological difference. Unfortunately, Essig was not able to explore in the western half of the island (Papua), because the province was closed for foreign scientific exploration for most of the 1980s. Therefore, apart from O. brassii, O. clemensiae and O. micrantha, Essig still followed Burret for the other Papuan taxa. Essig did not conduct any botanical exploration in the other parts of Malesia and merely followed Beccari when treating the extra-New Guinean taxa.
    The most recent list of Orania in New Guinea was published by Ferrero (1997). He followed the synopsis by Essig; however, he worked only in mainland New Guinea. Although he was able to work in Papua and Papua New Guinea, the number of species recognised by him agreed with Essig (1980), apart from one extra taxon from the Toricelli Mountains in the northern part of the border between Papua and Papua New Guinea with distichous leaves proposed as a new species but not formally described.
    In our synopsis the increased number of species is due partly to more extensive botanical explorations, especially in New Guinea and Madagascar and due also to a different opinion concerning several morphological characters considered unimportant by Essig. This affects particularly the treatment of Orania lauterbachiana. However, Essig's four new species are still accepted.
    (A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012)

Bibliography

A. A.P. Keim & J. Dransfield, A monograph of the genus Orania (Arecaceae: Oranieae) in Kew Bulletin 67. 2012
B. J. Dransfield & N. Uhl & C. Asmussen & W.J. Baker & M. Harley & C. Lewis, Genera Palmarum. The evolution and classification of palms. 2008
C. World Checklist of Arecaceae