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.
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.
Most species are large tree palms of the canopy or subcanopy of humid tropical rain forest in the lowlands or hills up to ca. 1700 m; Orania parva and O. oreophila are smaller palms of the forest undergrowth. There is some evidence that O. sylvicola avoids the highest rainfall areas within its range of distribution. Nothing is known of pollination or dispersal.
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.
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.