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The karuka (''Pandanus julianettii'', also called karuka nut and ''Pandanus'' nut) is a species of tree in the family
Pandanaceae Pandanaceae is a family of flowering plants native to the tropics and subtropics of the Old World, from West Africa through the Pacific. It contains 982 known species in five genera, of which the type genus, ''Pandanus'', is the most important, wi ...
and an important regional food crop in New Guinea. The nuts are more nutritious than
coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family ( Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the ...
s, and are so popular that villagers in the highlands will move their entire households closer to trees for the harvest season.


Names

The
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
"''julianettii''" honors naturalist
Amedeo Giulianetti Amedeo is an Italian given name meaning "lover of God", "loves God", or more correctly "for the love of God" and cognate to the Latin name Amadeus and the Spanish and Portuguese Amadeo. People with this name include: * A number of rulers and nob ...
, who found the original
type specimens In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...
. is a loanword from Tok Pisin. Sometimes the tree is called '' or 'karuka nut pandanus'. The term 'karuka' can apply to both ''Pandanus julianettii'' and '' P. brosimos'', though the latter is usually called 'wild karuka'. Both species, as well as '' P. dubius'', can be called 'pandanus nut'. In addition to ''P. brosimos'', 'wild karuka' can also refer to '' P. antaresensis'', '' P. iwen'', and '' P. limbatus'', but nuts from these trees are a much smaller part of the local diet. In contexts where multiple karuka species are discussed, ''P. julianettii'' is sometimes termed 'planted karuka'. ''P. julianettii'', ''P. iwen'', and ''P. brosimos'' are also in the subsection named '' Karuka'', which is in the monotypic section also named '' Karuka''. In New Guinea it goes by different names among each of the
Papuan people The indigenous peoples of West Papua in Indonesia and Papua New Guinea, commonly called Papuans, are Melanesians. There is genetic evidence for two major historical lineages in New Guinea and neighboring islands: a first wave from the Malay Arc ...
s. In the
Ankave language Ankave or Angave is a Papuan language spoken by the approximately 1,600 () Angave people in Kerema District, Gulf Province, Papua New Guinea. Phonology Vowels Diphthongs: Consonants Writing system An orthography using the Latin script has ...
it is . It is in the
Baruya language Yipma (pronounced as ''Hipma'') is an Angan language of Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilo ...
. The Huli language word is , and it is also in the
Duna language Duna (also known as ''Yuna'') is a Papuan language of Papua New Guinea. It may belong to the Trans New Guinea language family and is often further classified as a Duna-Pogaya language, for Bogaya appears to be Duna's closest relative, as evid ...
. In Kewa language it is ''aga'', but it is unclear which dialect(s). In the Kewa pandanus language it is ''rumala agaa''. The Kalam language term, in both standard and pandanus languages, is , but it can also be called or . The plant is called in the
Wiru language Wiru or Witu is the language spoken by the Wiru people of Ialibu-Pangia District of the Southern Highlands Province of Papua New Guinea. The language has been described by Harland Kerr, a missionary who lived in the Wiru community for many years. ...
. In the
Pole language Kewa is an Engan language complex of the Southern Highlands province of Papua New Guinea. A dictionary of the western dialect of Kewa has been compiled by . Kewa pandanus register Kewa's elaborate pandanus avoidance register, which is used on ...
it's called ''maisene''. It goes by ''ank'' in
Angal language Angal, or Mendi, is an Engan language complex of the Southern Highlands province of Papua New Guinea. Mendi has a pandanus language used during karuka harvest. References Engan languages Languages of Southern Highlands Province Panda ...
, and in the Wola dialect. The
Imbongu language Kaugel (Gawigl) is one of the languages spoken in the Southern Highlands (Papua New Guinea), Southern Highlands province of Papua New Guinea. Native speakers call the area on the Southern Highlands (Papua New Guinea), Southern Highlands side of t ...
word is . The plant also has many names on the other half of the island. In Indonesian it is called ( lit.) and (), but the latter can also refer to ''P. brosimos'' and ''P. iwen''. The Dani people call it ''tuke''. The
Lani people The Lani are an indigenous people in Puncak, Central Papua and Lanny Jaya, Highland Papua, usually labelled 'Western Dani' by foreign missionaries, or grouped—inaccurately—with the Dani people who inhabit the Baliem Valley to the east. Po ...
call it , but this might be a separate species in the complex.


Description

The species was originally described by Ugolino Martelli from only a few
drupe In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...
s in the collections of the Royal Botanic Gardens, Kew He was hesitant to describe it as a new species from only that, but the characteristics were so salient he published his description. The tree is
dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...
(individual plants either have male flowers or female ones), with male trees uncommon compared to females. It reaches in height, with a grey
trunk Trunk may refer to: Biology * Trunk (anatomy), synonym for torso * Trunk (botany), a tree's central superstructure * Trunk of corpus callosum, in neuroanatomy * Elephant trunk, the proboscis of an elephant Computing * Trunk (software), in rev ...
of in diameter and supported by buttress roots. The trunk has white mottling and is generally smooth with occasional warts or small knobs as well as rings of leaf scars. Inside the trunk is pithy and lacking cambium. The top of the tree sometimes branches, producing three or four crowns of leaves. Each crown will produce a single cluster of nuts, typically once every other season. Production is affected by the seasonality of local rainfall.
Leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
spiral up the trunk in opposite pairs. The large leathery leaves are long and wide. The apex of the leaf is attenuate and doubly-pleated, with prickles pointing up at the tip and along the
margins Margin may refer to: Physical or graphical edges *Margin (typography), the white space that surrounds the content of a page *Continental margin, the zone of the ocean floor that separates the thin oceanic crust from thick continental crust *Leaf ...
and midrib. The leaves are dark green on top and dull cyan underneath. The inflorescence on male trees is a densely-branched spadix with a dozen long spikes, each containing many staminate phalanges. In each phalange is a
column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...
3 mm long topped by up to 9
subsessile In botany, sessility (meaning "sitting", used in the sense of "resting on the surface") is a characteristic of plant parts (such as flowers and leaves) that have no stalk. Plant parts can also be described as subsessile, that is, not completely ...
anther The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...
s. The male flowers are white, and the whole male flowering organ may be up to long. The
pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
has a psilate
exine Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
(unornamented outer wall) 0.8 μm thick. The ornamentation is granular between echinae (short spines). The
ulcerate Ulcerate is a New Zealand-based extreme metal band formed by guitarist Michael Hoggard and drummer Jamie Saint Merat in 2000. The band have released six studio albums to date. The band have been featured in numerous articles as one of New Zeal ...
aperture is 3 μm in diameter. Pollen grains measure an average of 30 × 14.5 μm in size. On female trees, the inflorescence is a single ellipsoid or ovoid
syncarp Multi-fruits, also called collective fruits, are fruiting bodies formed from a cluster of flowers, the ''inflorescence''. Each flower in the inflorescence produces a fruit, but these mature into a single mass. After flowering the mass is called a ...
, or fruiting head, with off-white
bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...
s. Female flowers can produce fruit without pollination, and are typically the only trees cultivated. The tree stops making leaves when new fruit is growing. The syncarp has up to a thousand densely-packed single-celled carpels that later turn into drupes. The clavate,
pentagon In geometry, a pentagon (from the Greek πέντε ''pente'' meaning ''five'' and γωνία ''gonia'' meaning ''angle'') is any five-sided polygon or 5-gon. The sum of the internal angles in a simple pentagon is 540°. A pentagon may be simpl ...
al drupes measure up to 12 cm long and have a sharpened base, but typically are 9×1.5 cm, and are a pale blue-green color. Each cluster contains about 1000 nuts. The endocarp is bony and thin, 5½ cm long, with rounded edges about 1½ cm wide. The seed-bearing
locule A locule (plural locules) or loculus (plural loculi) (meaning "little place" in Latin) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus). In angiosperms (flowering plants), the term ''locule'' usu ...
is around 4 cm long. The core of the mature head ( mesocarp) has an appearance like honeycomb and is spongy and pink. The top of the mesocarp is fibrous, from 3 cm long and up. Though Martelli did not have a complete syncarp, he knew the cluster of fruit must be large, estimating at least 30 cm in diameter. He was correct, as the fruiting cluster is typically 15 to 30 cm in diameter. A mature head and stalk weigh up to 16 kg, but average 6 kg. It most closely resembles '' P. utilissimus'', which is found the Philippines. People also harvest and eat nuts of ''P. antaresensis'', ''P. brosimos'', ''P. dubius'', ''P. iwen'', and ''P. limbatus'', and '' P. odoratissima''


Cultivars

There are up to 45
cultivars A cultivar is a type of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and when Plant propagation, propagated retain those traits. Methods used to propagate cultivars include: division, root and st ...
of karuka, many with different kernel shapes. There are likely many more, as some are known only to a small number of people in a single settlement. 'Tabuna' and 'Henga' are some of the most important. '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. At least two varieties are edible raw. Named varieties include: * * * * * * * * Goalia * Gurubu * Hagidara * * * Henga * Homagal-iba * * Honde * * * * Kabali * * Kai * * * Kebali * * * * * * Mabu * * * * * * * Ngaule * * * * Padua * Pari * * * * * * * * Tabuna * * * * Tenyon * * * Tolo * * * Tumbi * Tumbu * It is possible a cultivar is listed more than once under different names, as Papua New Guinea has a very high linguistic diversity.
Benjamin Clemens Stone Benjamin Clemens Masterman Stone (February 7, 1933, Shanghai, China – March 19, 1994 Philippine National Museum) was a British–American botanist. Stone was born in Shanghai, China to a British father, who worked for the government, and an ...
posits that ''P. julianettii'' and ''P. brosimos'' are a single species with many varieties, but does not support this point. However, Simon G. Haberle notes that the pollen of the two trees are indistinguishable by
light microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...
. ''P. iwen'' may also be part of the species complex.


Distribution

Giulianetti's type specimens were collected from Vanapa, British New Guinea (now southern Papua New Guinea). The tree can be found cultivated or wild on New Guinea, both in PNG and
Papua province Papua is a province of Indonesia, comprising the northern coast of Western New Guinea together with island groups in Cenderawasih Bay to the west. It roughly follows the borders of Papuan customary region of Tabi Saireri. It is bordered by ...
. Wild trees are found on the Huon Peninsula and in the highlands of New Guinea's central cordillera. In Papua New Guinea, the tree is most commonly grown in Southern Highlands, Western Highlands, Eastern Highlands, Enga, and Chimbu Provinces, and it is found in all provinces on the mainland except East Sepik. It grows in montane forests between 1,300 and 3,300 m in elevation in areas that get 2–5 m mean annual precipitation. It grows in both dry and wet soils, but prefers good soil fertility. Trees will grow in clumped groups of 5 to 10 individuals per hectare.


Ecology

Karuka produces fruit around February, with an occasional secondary season in July. Typically each branch will only flower every other year. The natural pollination syndrome is unknown, but the flowers can be pollinated by humans. Seed dispersal is by humans, birds, and other animals. According to the Kalam people of Madang Province, the Lorentz's mosaic-tailed rat (''Paramelomys lorentzii'') helps spread karuka seeds. A fallen syncarp will disintegrate completely in about 3 days in the forest. Fungal
pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
of karuka include leaf spot, diffuse leaf spot, black leaf mould (''
Lembosia pandani ''Lembosia'' is a genus of fungi in the Asterinaceae family. The relationship of this taxon to other taxa within the class is unknown ('' incertae sedis''), and it has not yet been placed with certainty into any order Order, ORDER or Orders may ...
''),
sooty mold Sooty mold (also spelled sooty mould) is a collective term for different Ascomycete fungi, which includes many genera, commonly '' Cladosporium'' and '' Alternaria''. It grows on plants and their fruit, but also environmental objects, like fences ...
('' Meliola juttingii''), and fungus on seeds (''
Macrophoma pandani ''Macrophoma'' is a genus of anamorphic fungi in the family Botryosphaeriaceae. Some of these species are pathogenic, for example '' M. musae'' is a banana fungus. Species *''Macrophoma abietis'' *'' Macrophoma abietis-pectinatae'' *'' Macrop ...
''). The leaf moulds do not do much damage. The sooty mould seems to grow on insect
frass Frass refers loosely to the more or less solid excreta of insects, and to certain other related matter. Definition and etymology ''Frass'' is an informal term and accordingly it is variously used and variously defined. It is derived from the G ...
. The black leaf mold only affects some varieties. The bacteria ''Pectobacterium carotovorum'' subsp. ''carotovorum'' can also cause
bacterial soft rot Bacterial soft rots are caused by several types of bacteria, but most commonly by species of gram-negative bacteria, ''Erwinia'', '' Pectobacterium'', and ''Pseudomonas''. It is a destructive disease of fruits, vegetables, and ornamentals found wo ...
and necrosis on the leaves, but causes more severe damage to the related species ''
Pandanus conoideus ''Pandanus conoideus'' is a plant in the ''Pandanus'' family from New Guinea. Its fruit is eaten in Papua New Guinea and Papua, Indonesia. The fruit has several names: ''marita'' (in Papua New Guinea local language), or ''buah merah'' ("red fruit ...
''. Longhorn grasshoppers (Tettigoniidae) are serious insect pests. ''
Segestes gracilis Segestes was a nobleman of the Germanic tribe of the Cherusci involved in the events surrounding the Roman attempts to conquer northern Germany during the reign of Roman Emperor Augustus. Arminius, the Cheruscan noble and military leader, had m ...
'' and ''
Segestidea montana ''Segestidea montana'' is a species of insect in the family Tettigoniidae Insects in the family Tettigoniidae are commonly called katydids (especially in North America), or bush crickets. They have previously been known as "long-horned grass ...
'' eat the leaves and can sometimes kill trees. Growers will stuff leaves and grass in between the leaves of the crown to keep insects out. 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. Woodboring beetles sometimes attack the prop root of the tree. Possums also eat the nuts, as do rodents such as squirrel-toothed rats (''Anisomys imitator''),
eastern white-eared giant rat The eastern white-eared giant rat (''Hyomys goliath'') is a species of rodent in the family Muridae. It is found only in Papua New Guinea. The species has been known to eat karuka nuts (''Pandanus julianettii''), and growers will put platforms o ...
s (''Hyomys goliath''),
Rothschild's woolly rat Rothschild's woolly rat (''Mallomys rothschildi'') is a species of rodent in the family Muridae. It is found on the island of New Guinea: both in the West Papua region of Indonesia and Papua New Guinea. The species has been known to eat karuka ...
s (''Mallomys rothschildi''), and giant naked-tailed rats (''Uromys anak''). Growers will put platforms or other obstacles on the trunks of trees to keep the pests out. Harvested nuts are often beset by
rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...
s and cockroaches. Hanging nuts in the smoky areas above fires can prevent this, but after a while the taste of the nuts is affected.


Use by humans

On New Guinea karuka is cultivated crop, and has been used as a major food source since nearly 31,000 years ago in the Pleistocene. In PNG nearly 2 million people (almost half the rural population) live in regions where karuka is commonly eaten. There is high demand for it in the New Guinea Highlands: Entire households (including pigs, who are sometimes fed the fruits) will move from the valleys to higher elevations at harvest time, often for several weeks. Each household will average 12 to 176 trees. Trade in karuka is small-scale and not commercial. Local marketplaces typically will have 12 to 50 fruits for sale. With some coordination between state agencies and private sector, karuka could have export market access. 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. Diets of tree owners could also be negatively influenced by rapid commercialization. The
endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo and ...
, a white kernel, is eaten raw, roasted,
smoked Smoking is the process of flavoring, browning, cooking, or preserving food by exposing it to smoke from burning or smoldering material, most often wood. Meat, fish, and ''lapsang souchong'' tea are often smoked. In Europe, alder is the tradi ...
, or mumued. Nuts that aren't immediately eaten are typically
sun-dried Food drying is a method of food preservation in which food is dried (dehydrated or desiccated). Drying inhibits the growth of bacteria, yeasts, and mold through the removal of water. Dehydration has been used widely for this purpose since a ...
for storage. The karuka kernels have a sweet,
coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family ( Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the ...
taste, or savory and like walnuts. Smoked or cooked karuka is either stored in the rafters or sold at local marketplaces. The uncooked clusters can also be stored for months buried in waterlogged earth, which possibly
ferments Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...
it. It is a regional
staple food A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
and one of the few plants in the area with a high protein content. The spongy core of the
multiple fruit Multi-fruits, also called collective fruits, are fruiting bodies formed from a cluster of flowers, the ''inflorescence''. Each flower in the inflorescence produces a fruit, but these mature into a single mass. After flowering the mass is called a ...
cluster can also be cooked and eaten after the nuts are removed. The high fat content means the nuts can be processed into an edible yellow oil. Karuka contains 52.39% oleic acid, 44.90% palmitic acid, and 0.19%
stearic acid Stearic acid ( , ) is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a waxy solid and its chemical formula is C17H35CO2H. Its name comes from the Greek word στέαρ "''stéar''", which means tallow. ...
. The oil is a good source of Vitamin E ( α-tocopherol 5.03 mg/100 g). The color of the oil is from the
carotenoid Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, and Fungus, fungi. Carotenoids give the characteristic color to pumpki ...
s, which are at a concentration of 2.75 µg/g. The
antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
activity for the oil is fairly low, and it is higher in saturated than unsaturated fats. 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''). But the connections, if any, are unclear. Trunks and buttress roots are used for building. The sheets of bark are used for house walls. The leaves are used for bush shelters and raincapes. The leaves were the preferred building material for housing in Papua New Guinea before
colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 a ...
contact. The durable white spathe leaves on male inflorescences are used by the
Wola people The Wola people are an indigenous group of the Southern Highlands Province of Papua New Guinea. They live in five valleys northeast of Lake Kutubu. The Wola are sedentary and practice swidden agriculture. Their main staple is sweet potato; lesser ...
to wrap pearl shells. Karuka can be cultivated by cutting a mature branch and replanting it ( vegetative propagation). Suckers can also be replanted. Nurseries also plant seeds directly. New nuts will grow when a tree is at least five or six years old, and can keep producing for up to fifty years. The tree can tolerate temperatures down to 3 °C for extended periods and 0 °C for short periods. The USDA hardiness is 10–12, and is hardy to zone 10 in the UK system. In Upper Karint near Pingirip, karukas are planted as boundary lines between garden plots.


In culture

In PNG's Central Province Premier Rugby League the team for
Goilala District Goilala District is a district of Central Province in Papua New Guinea. It is one of the four administrative districts that make up the province. Local-level government areas * Guari Rural * Tapini Rural * Woitape Rural Towns and major vill ...
is called the Karukas.


See also

* Domesticated plants and animals of Austronesia * Pandanus languages


References

{{Taxonbar, from=Q15578194 Pandanus Plants described in 1907 Trees of New Guinea Edible nuts and seeds Fruits originating in Asia Tropical fruit Tropical agriculture Non-timber forest products Papua New Guinean cuisine