| Karuka | |
|---|---|
 | |
| Pandanus julianettii fruit cluster | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Pandanales |
| Family: | Pandanaceae |
| Genus: | Pandanus |
| Subgenus: | Pandanussubg. Lophostigma |
| Section: | Pandanussect. Karuka |
| Species: | P. julianettii |
| Binomial name | |
| Pandanus julianettii | |
| Synonyms | |
 | |||||||||||||||||||||||||||||||||||||||||||
| Nutritional value per 100 g | |||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Energy | 2,259–2,929 kJ (540–700 kcal) | ||||||||||||||||||||||||||||||||||||||||||
28-33.5 g | |||||||||||||||||||||||||||||||||||||||||||
| Sugars | 5 g | ||||||||||||||||||||||||||||||||||||||||||
| Dietary fibre | 9.2-25 g | ||||||||||||||||||||||||||||||||||||||||||
35.6-47 g | |||||||||||||||||||||||||||||||||||||||||||
| Saturated | 18 g | ||||||||||||||||||||||||||||||||||||||||||
| Trans | 0 | ||||||||||||||||||||||||||||||||||||||||||
11.9-18 g | |||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||
| Other constituents | Quantity | ||||||||||||||||||||||||||||||||||||||||||
| Water | 9% | ||||||||||||||||||||||||||||||||||||||||||
| Cholesterol | 0 | ||||||||||||||||||||||||||||||||||||||||||
| †Percentages estimated usingUS recommendations for adults,[4] except for potassium, which is estimated based on expert recommendation from theNational Academies.[5] Source:[3][2] | |||||||||||||||||||||||||||||||||||||||||||
| Nutritional value per 100 g | |||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dietary fibre | 5.3 g | ||||||||||||||||||||||||||||||||||||||
0.43 g | |||||||||||||||||||||||||||||||||||||||
8.5 g | |||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||
| Other constituents | Quantity | ||||||||||||||||||||||||||||||||||||||
| Cholesterol | 0 | ||||||||||||||||||||||||||||||||||||||
| †Percentages estimated usingUS recommendations for adults.[4] Source:[3][2] | |||||||||||||||||||||||||||||||||||||||
Thekaruka (Pandanus julianettii, also calledkaruka nut andPandanus nut) is a species of tree in the screwpine family (Pandanaceae) and an important regional food crop inNew Guinea.[6] The nuts are more nutritious thancoconuts,[2] and are so popular that villagers in thehighlands will move their entire households closer to trees for the harvest season.[7][8]
The species was originallydescribed in 1908 byUgolino Martelli from only a fewdrupes in the collections of theRoyal Botanic Gardens, Kew[1] He was hesitant to describe it as a new species from only that, but the characteristics were so salient he published his description.[1]
The tree isdioecious (individual plants either have male flowers or female ones),[6] with male trees uncommon compared to females.[3] It reaches 10–30 metres (33–98 ft) in height, with a greytrunk[2] of 30 cm (12 in) in diameter and supported by prop roots or flyingbuttress roots up to 12 m (39 ft)[9] in length and 15 cm (5.9 in) or more in diameter.[6] The trunk has white mottling and is generally smooth with occasional warts or small knobs as well as rings ofleaf scars.[10] Inside the trunk is pithy and lackingcambium.[10] The top of the tree sometimes branches, producing three or four crowns of leaves.[3] Each crown will produce a single cluster of nuts, typically once every other season.[3] Production is affected by the seasonality of local rainfall.[7]
Leaves spiral up the trunk inopposite pairs.[3][6] The large leathery leaves are 3–4 m (9.8–13.1 ft) long[3] and 8–12 cm (3.1–4.7 in) wide.[6] The apex of the leaf isattenuate and doubly-pleated, withprickles pointing up at the tip[6] and along themargins andmidrib.[2] The leaves are dark green on top and dull cyan underneath.[10]
Theinflorescence on male trees is a densely-branchedspadix with a dozen long spikes, each containing manystaminate phalanges.[6] In each phalange is acolumn 3 mm long topped by up to 9subsessileanthers.[6] The male flowers are white,[3] and the whole male flowering organ may be up to 2 m (6 ft 7 in) long.[10]
Thepollen has apsilateexine (unornamented outer wall) 0.8 μm thick.[11] The ornamentation is granular betweenechinae (short spines).[11] Theulcerateaperture is 3 μm in diameter.[11] Pollen grains measure an average of 30 × 14.5 μm in size.[11]
On female trees, the inflorescence is a single ellipsoid or ovoidsyncarp, or fruiting head, with off-whitebracts.[6] Female flowers can produce fruit without pollination,[2] and are typically the only trees cultivated.[10] The tree stops making leaves when new fruit is growing.[3] The syncarp has up to a thousand densely-packed single-celledcarpels that later turn into drupes.[6][3]
Theclavate,pentagonal drupes measure up to 12 cm long and have a sharpened base,[1] but typically are 9×1.5 cm,[6] and are a pale blue-green colour.[10] Each cluster contains about 1000 nuts.[3] Theendocarp is bony and thin,[6] 5½ cm long, with rounded edges about 1½ cm wide.[1] The seed-bearinglocule is around 4 cm long.[1] The core of the mature head (mesocarp) has an appearance likehoneycomb and is spongy[6] and pink.[3] The top of the mesocarp is fibrous, from 3 cm long and up.[1] Though Martelli did not have a complete syncarp, he knew the cluster of fruit must be large, estimating at least 30 cm in diameter.[1] He was correct, as the fruiting cluster is typically 15 to 30 cm in diameter.[3] A mature head and stalk weigh up to 16 kg,[6] but average 6 kg.[3] but weights up to 27 kg (60 lb) have been reported.[12][13]
It most closely resemblesP. utilissimus, which is found thePhilippines.[1] People also harvest and eat nuts ofP. antaresensis,P. brosimos,P. dubius,P. iwen, andP. limbatus, andP. odoratissima[7]
Thespecific epithet "julianettii" honors naturalistAmedeo Giulianetti, who found the originaltype specimens.[1]
Karuka is aloanword fromTok Pisin.[14][15] Sometimes the tree is called 'karuga'[16][10][17] or 'karuka nut pandanus'.[18] The term 'karuka' can apply to bothPandanus julianettii andP. brosimos, though the latter is usually called 'wild karuka'.[7] Both species, as well asP. dubius, can be called 'pandanus nut'.[7] In addition toP. brosimos, 'wild karuka' can also refer toP. antaresensis,[18]P. iwen, andP. limbatus, but nuts from these trees are a much smaller part of the local diet.[7] In contexts where multiple karuka species are discussed,P. julianettii is sometimes termed 'planted karuka'.[18]P. julianettii,P. iwen, andP. brosimos are also in thesubsection namedKaruka, which is in themonotypicsection also namedKaruka.[19]
InNew Guinea it has different names among each of thePapuan peoples.[6] In theAnkave language it isxweebo.[6] It isyase in theBaruya language.[6] TheHuli language word isanga,[20] and it is alsoanga in theDuna language.[3][6][21] InKewa language it isaga,[3][6][17] but it is unclear which dialect(s). In the Kewapandanus language it isrumala agaa.[17][22] TheKalam language term, in both standard and pandanus languages, isalŋaw,[23][24] but it can also be calledkumi orsnay.[25] The plant is calledama in theWiru language.[3][6] In thePole language it's calledmaisene.[3][6] It goes byank inAngal language,[3][6] andaenk in the Wola dialect.[10] TheImbongu language word isamo.[6][3][22]
The plant also has many names on the other half of the island. InIndonesian it is calledpandan kelapa (lit.coconut pandan) andkelapa hutan (forest coconut),[26] but these names can also refer toP. brosimos andP. iwen.[27] According to field research by Kiwo et al. in Melagineri District,Lanny Jaya, theLani people call itgawin, withworomo forP. brosimos,owandak forP. iwen.[28] Meanwhile according to field research by Zebua et al. in Pirime District, Lanny Jaya,woromo is used to refer toP. iwen,[29] while in another study inJayawijaya, the Lani usedworomo forP. julianettii with theDani people call ittuke,[26][27] hence the names have been used interchangeably by multiple publications from different regions and might be a separate species in thecomplex.
There are up to 45cultivars of karuka,[10] many with different kernel shapes.[3] There are likely many more, as some are known only to a small number of people in a single settlement.[10] 'Tabuna' and 'Henga' are some of the most important.[2] 'Tabuna' is popular because it is high-yielding, tastes good, and has notaboos on who/what can eat it and how/if it is cooked.[2] At least two varieties are edible raw.[3]
Named varieties include:[2][10]
It is possible a cultivar is listed more than once under different names, as Papua New Guinea has a very highlinguistic diversity.
Benjamin Clemens Stone posits thatP. julianettii andP. brosimos are a single species with many varieties, but does not support this point.[14] However,Simon G. Haberle notes that the pollen of the two trees are indistinguishable bylight microscopy.[11]P. iwen may also be part of thespecies complex.[19]
Giulianetti's type specimens were collected fromVanapa,British New Guinea[1] (now southernPapua New Guinea). The tree can be found cultivated or wild onNew Guinea, both in PNG and Indonesia (Central Papua &Highland Papua).[6][3] Wild trees are found on theHuon Peninsula and in the highlands of New Guinea's centralcordillera.[6][7] In Papua New Guinea, the tree is most commonly grown inSouthern Highlands,Western Highlands,Eastern Highlands,Enga, andChimbu Provinces, and it is found in all provinces on the mainland exceptEast Sepik.[18] It grows inmontane forests[14] between 1,300 and 3,300 m in elevation in areas that get 2–5 m mean annualprecipitation.[6][7] It grows in both dry and wet soils,[6][7] but prefers good soil fertility.[3] Trees will grow in clumped groups of 5 to 10 individuals per hectare.[7]
Karuka produces fruit around February, with an occasional secondary season in July.[3] Typically each branch will only flower every other year.[3] The naturalpollination syndrome is unknown, but the flowers can bepollinated by humans.[7]Seed dispersal is by humans,birds, and otheranimals.[7] According to theKalam people ofMadang Province, theLorentz's mosaic-tailed rat (Paramelomys lorentzii) helps spread karuka seeds.[25] A fallen syncarp will disintegrate completely in about 3 days in the forest.[2]
Fungalpests of karuka includeleaf spot,diffuse leaf spot,black leaf mould (Lembosia pandani),sooty mould (Meliola juttingii), and fungus on seeds (Macrophoma pandani).[3] The leaf moulds do not do much damage.[3] The sooty mould seems to grow on insectfrass.[3] The black leaf mould only affects some varieties.[3]
The bacteriaPectobacterium carotovorum subsp.carotovorum can also causebacterial soft rot and necrosis on the leaves, but causes more severe damage to the related speciesPandanus conoideus.[16]
Bush crickets are serious insect pests, includingSegestes gracilis andSegestidea montana, which eat the leaves and can sometimes kill trees.[3] Growers will stuff leaves and grass in between the leaves of the crown to keep insects out.[3] An unknown species of blackgrub will burrow into the cluster and eat the spongy core, causing the nuts to turn black and the whole bunch to fall off the tree.[3]Woodboring beetles sometimes attack the prop root of the tree.[3]
Possums also eat the nuts,[3] as dorodents such assquirrel-toothed rats (Anisomys imitator),eastern white-eared giant rats (Hyomys goliath),Rothschild's woolly rats (Mallomys rothschildi), andgiant naked-tailed rats (Uromys anak).[10] Growers will put platforms or other obstacles on the trunks of trees to keep the pests out.[3][10]
Harvested nuts are often damaged byrats andcockroaches.[3] Hanging nuts in the smoky areas above fires can prevent this, but after a while the taste of the nuts is affected.[3]
On New Guinea karuka is cultivated crop,[6] and has been used as a major food source since nearly 31,000 years ago in thePleistocene.[15] In PNG nearly 2 million people (almost half the rural population) live in regions where karuka is commonly eaten.[18] There is high demand for it in theNew Guinea Highlands: Entire households (includingpigs, who are sometimes fed the fruits[2]) will move from the valleys to higher elevations at harvest time,[7] often for several weeks.[8] Each household will average 12 to 176 trees.[8]
Trade in karuka is small-scale and not commercial.[7] Localmarketplaces typically will have 12 to 50 fruits for sale.[8] With some coordination between state agencies and private sector, karuka could have exportmarket access.[18] The crop has a medium potential for large-scale sustainable commercialization in the region, but care must be taken in the sensitive local environments to expanded agriculture.[7] Diets of tree owners could also be negatively influenced by rapid commercialization.[7]
Theendosperm, a white kernel, is eaten raw,roasted,smoked,[6] ormumued.[3] Nuts that aren't immediately eaten are typicallysun-dried for storage.[3] The karuka kernels have a sweet,coconut taste,[6][10][26] or savory and likewalnuts.[27] Smoked or cooked karuka is either stored in therafters or sold at local marketplaces.[6] The uncooked clusters can also be stored for months buried in waterlogged earth,[6][3][2] which possiblyferments it.[10] It is a regionalstaple food and one of the few plants in the area with a highprotein content.[6] The spongy core of themultiple fruit cluster can also be cooked and eaten after the nuts are removed.[6][3]
The highfat content means the nuts can be processed into an edible yellowoil.[26] Karuka contains 52.39%oleic acid, 44.90%palmitic acid, and 0.19%stearic acid.[27] The oil is a good source ofVitamin E (α-tocopherol 5.03 mg/100 g).[26] The colour of the oil is from thecarotenoids, which are at a concentration of 2.75 μg/g.[26] Theantioxidant activity for the oil is fairly low, and it is higher insaturated thanunsaturated fats.[26]
Some subjective reports indicate that children are healthier after karuka season, but there may also be increased incidence oftropical ulcers andpig-bel (caused byClostridium perfringens).[2] But the connections, if any, are unclear.
Trunks and buttress roots are used for building.[6] The sheets of bark are used for house walls.[10] The leaves are used forbushshelters[6] andraincapes.[10] The leaves were the preferred building material for housing in Papua New Guinea beforecolonial contact.[30] The durable whitespathe leaves on male inflorescences are used by theWola people to wrappearl shells.[10]
Karuka can be cultivated by cutting a mature branch and replanting it (vegetative propagation).[3]Suckers can also be replanted.[3]Nurseries also plant seeds directly.[3] New nuts will grow when a tree is at least five or six years old, and can keep producing for up to fifty years.[3][2] The tree can tolerate temperatures down to 3 °C for extended periods and 0 °C for short periods.[21] TheUSDA hardiness is 10–12, and is hardy to zone 10 in theUK system.[31]
InUpper Karint nearPingirip, karukas are planted as boundary lines between garden plots.[3]
In PNG'sCentral Province PremierRugby League the team forGoilala District is called the Karukas.[32]