The karuka (Pandanus julianettii, also called karuka nut and Pandanus nut) is a species of tree in the screwpine family (Pandanaceae) and an important regional food crop in New Guinea.[6] The nuts are more nutritious than coconuts,[2] and are so popular that villagers in the highlands will move their entire households closer to trees for the harvest season.[7][8]
Karuka is a loanword from Tok Pisin.[9][10] Sometimes the tree is called 'karuga'[11][12][13] or 'karuka nut pandanus'.[14] The term 'karuka' can apply to both Pandanus julianettii and P. brosimos, though the latter is usually called 'wild karuka'.[7] Both species, as well as P. dubius, can be called 'pandanus nut'.[7] In addition to P. brosimos, 'wild karuka' can also refer to P. antaresensis,[14]P. iwen, and P. 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'.[14]P. julianettii, P. iwen, and P. brosimos are also in the subsection named Karuka, which is in the monotypicsection also named Karuka.[15]
The plant also has many names on the other half of the island. In Indonesian it is called pandan kelapa (lit.coconut pandan) and kelapa hutan (forest coconut),[22] but these names can also refer to P. brosimos and P. iwen.[23] According to field research by Kiwo et al. in Melagineri District, Lanny Jaya, the Lani people call it gawin, with woromo for P. brosimos, owandak for P. Iwen.[24] Meanwhile according to field research by Zebua et al. in Pirime District, Lanny Jaya, woromo is used to refer to P. Iwen,[25] while in another study in Jayawijaya, the Lani used woromo for P. julianettii with the Dani people call it tuke,[22][23] hence the names have been used interchangeably by multiple publications from different regions and might be a separate species in the complex.
Description
The species was originally described by Ugolino Martelli from only a few drupes in the collections of the Royal 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 is dioecious (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 grey trunk[2] of 30 centimetres (12 inches) in diameter and supported by prop roots or flying buttress roots up to forty feet (twelve meters) in length and six inches (15 cm) or more in diameter..[6] The trunk has white mottling and is generally smooth with occasional warts or small knobs as well as rings of leaf scars.[12] Inside the trunk is pithy and lacking cambium.[12] 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 in opposite pairs.[3][6] The large leathery leaves are 3–4 metres (9.8–13.1 ft) long[3] and 8–12 centimetres (3.1–4.7 in) wide.[6] The apex of the leaf is attenuate and doubly-pleated, with prickles pointing up at the tip[6] and along the margins and midrib.[2] The leaves are dark green on top and dull cyan underneath.[12]
The inflorescence on male trees is a densely-branched spadix with a dozen long spikes, each containing many staminate phalanges.[6] In each phalange is a column 3 mm long topped by up to 9 subsessileanthers.[6] The male flowers are white,[3] and the whole male flowering organ may be up to 2 metres (6 ft 7 in) long.[12]
The pollen has a psilateexine (unornamented outer wall) 0.8 μm thick.[26] The ornamentation is granular between echinae (short spines).[26] The ulcerateaperture is 3 μm in diameter.[26] Pollen grains measure an average of 30 × 14.5 μm in size.[26]
On female trees, the inflorescence is a single ellipsoid or ovoid syncarp, or fruiting head, with off-white bracts.[6] Female flowers can produce fruit without pollination,[2] and are typically the only trees cultivated.[12] The tree stops making leaves when new fruit is growing.[3] The syncarp has up to a thousand densely-packed single-celled carpels that later turn into drupes.[6][3]
The clavate, 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 color.[12] Each cluster contains about 1000 nuts.[3] The endocarp is bony and thin,[6] 5½ cm long, with rounded edges about 1½ cm wide.[1] The seed-bearing locule is around 4 cm long.[1] The core of the mature head (mesocarp) has an appearance like honeycomb 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 sixty pounds ((27,3 kilograms) have been reported.[27]
It most closely resembles P. utilissimus, which is found the Philippines.[1] People also harvest and eat nuts of P. antaresensis, P. brosimos, P. dubius, P. iwen, and P. limbatus, and P. odoratissima[7]
Cultivars
"Pebet" redirects here. For the bird mentioned in Metei culture, see Pebet (bird).
There are up to 45 cultivars of karuka,[12] 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.[12] 'Tabuna' and 'Henga' are some of the most important.[2] 'Tabuna' is popular because it is high-yielding, tastes good, and has no taboos on who/what can eat it and how/if it is cooked.[2] At least two varieties are edible raw.[3]
Longhorn grasshoppers (Tettigoniidae) are serious insect pests.[3]Segestes gracilis and Segestidea montana 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 black grub 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]
Harvested nuts are often beset by rats and cockroaches.[3] Hanging nuts in the smoky areas above fires can prevent this, but after a while the taste of the nuts is affected.[3]
Use by humans
On New Guinea karuka is cultivated crop,[6] and has been used as a major food source since nearly 31,000 years ago in the Pleistocene.[10] In PNG nearly 2 million people (almost half the rural population) live in regions where karuka is commonly eaten.[14] There is high demand for it in the New Guinea Highlands: Entire households (including pigs, 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] Local marketplaces typically will have 12 to 50 fruits for sale.[8] With some coordination between state agencies and private sector, karuka could have export market access.[14] 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]
The endosperm, a white kernel, is eaten raw, roasted, smoked,[6] or mumued.[3] Nuts that aren't immediately eaten are typically sun-dried for storage.[3] The karuka kernels have a sweet, coconut taste,[6][12][22] or savory and like walnuts.[23] Smoked or cooked karuka is either stored in the rafters or sold at local marketplaces.[6] The uncooked clusters can also be stored for months buried in waterlogged earth,[6][3][2] which possibly ferments it.[12] It is a regional staple food and one of the few plants in the area with a high protein content.[6] The spongy core of the multiple fruit cluster can also be cooked and eaten after the nuts are removed.[6][3]
Some subjective reports indicate that children are healthier after karuka season, but there may also be increased incidence of tropical ulcers and pig-bel (caused by Clostridium 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.[12] The leaves are used for bushshelters[6] and raincapes.[12] The leaves were the preferred building material for housing in Papua New Guinea before colonial contact.[28] The durable white spathe leaves on male inflorescences are used by the Wola people to wrap pearl shells.[12]
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.[17] The USDA hardiness is 10–12, and is hardy to zone 10 in the UK system.[29]
In Upper Karint near Pingirip, karukas are planted as boundary lines between garden plots.[3]
^ abcdefghijklmnoRose, C. J. (1982). Bourke, Richard Michael; Kesavan, V. (eds.). "Preliminary Observations on the Pandanus nut (Pandanus jiulianettii Martelli)". Proceedings of the Second Papua New Guinea Food Crops Conference. 1: 160–167. OCLC17294235.
^ abNational Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee to Review the Dietary Reference Intakes for Sodium and Potassium (2019). Oria, Maria; Harrison, Meghan; Stallings, Virginia A. (eds.). Dietary Reference Intakes for Sodium and Potassium. The National Academies Collection: Reports funded by National Institutes of Health. Washington, DC: National Academies Press (US). ISBN978-0-309-48834-1. PMID30844154. Archived from the original on 2024-05-09. Retrieved 2024-06-21.
^ abcdefghijklmnopBourke, Richard Michael (1994). "Edible indigenous nuts in Papua New Guinea"(PDF). In Stevens, M.L.; Bourke, Richard Michael; Evans, Barry R. (eds.). South Pacific Indigenous Nuts. Proceedings of a workshop held from 31 October to 4 November 1994 at Le Lagon Resort, Port Vila, Vanuatu. Australian Centre for International Agricultural Research Proceedings. Vol. 69. Canberra: Australian Centre for International Agricultural Research. pp. 45–55. ISBN1-86320-485-7. OCLC38390455. Retrieved 27 September 2018.
^ abTomlinson, D. L. (January 1988). "A Leaf and Fruit Disease of Pandanus conoideus caused by Erwinia carotovora subsp. carotovora in Papua New Guinea". Journal of Phytopathology. 121 (1): 19–25. doi:10.1111/j.1439-0434.1988.tb00948.x. ISSN0931-1785. OCLC4660013776.
^ ab"Pandanus julianettii". Ecocrop. Food and Agriculture Organization of the UN. 1993–2007. Archived from the original on 6 December 2018. Retrieved 26 October 2018.
^ abMajnep, Ian Saem; Bulmer, Ralph (1977). Birds of my Kalam Country [Mn̄mon Yad Kalam Yakt]. illustrations by Christopher Healey. New Zealand: Auckland University Press. pp. 53, 150, 152. ISBN9780196479538. OCLC251862814.
^Pawley, Andrew (1992). "Kalam Pandanus Language: An Old New Guinea Experiment in Language Engineering". In Dutton, Tom E.; Ross, Malcolm; Tryon, Darrell (eds.). The Language Game: Papers in Memory of Donald C. Laycock. Pacific Linguistics Series C. Vol. 110. Memory of Donald C. Laycock. Canberra: Department of Linguistics, Research School of Pacific Studies, Australian National University. pp. 313–334. ISBN0-85883-400-6. ISSN0078-7558. OCLC222981840.
^ abPawley, Andrew; Bulmer, Ralph; Kias, John; Gi, Simon Peter; Majnep, Ian Saem (2011). A Dictionary of Kalam with Ethnographic Notes. Pacific Linguistics. Vol. 630. Canberra: Pacific Linguistics. OCLC798464842.