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45
THERE are more than 40 indigenous plant species
with an edible kernel in Papua New Guinea
(PNG). These are listed, together with an assess-
ment of their significance in the agricultural sys-
tems and villagers’ diets, in Table 1. Eleven of
these are classed here as very significant, sig-
nificant or important in village agriculture. The
remainder are classed as minor or very minor and
are commonly self-sown. This paper is concerned
with six species that, it is judged, have potential
for commercial development. The main criterion
for selecting these species is acceptance of the
nut by people from outside the area where it was
traditionally grown. The six species are cut nut
(pao) (Barringtonia procera), galip (Canarium
indicum), karuka (Pandanus julianettii), okari nut
(Terminalia kaernbachii), Polynesian chestnut
(aila) (Inocarpus fagifer) and sea almond (talis,
Java almond) (Terminalia catappa). All six spe-
cies, particularly galip, karuka and okari nut, are
marketed locally and are sometimes sent to more
distant markets within PNG. New commercial
ventures are currently being established for
roasted galip nut in East and West New Britain,
and for fresh okari nuts from the Managalas Pla-
teau in Northern Province.
Agricultural environments in PNG
People live and practise agriculture in a wide
range of environments in PNG. These cover an
altitude range from sea level to 2800 m (and up
to 3100 m for wild karuka nuts); a rainfall range
of 1000 to 8000 mm a year; from climates with
no dry months to those with an average of seven
dry months a year; and landforms that include
raised coral reefs, coastal plains, mountains and
hills, colluvial fans and highland valleys. Nut-
bearing species and other tree crops are grown
in all inhabited environments, but there are three
in which they are particularly important for vil-
lagers’ food supply.
The first of these environments is the high
altitude zone (1800–2400 m) and the very high
altitude zone (2400–3000 m), where karuka and
wild karuka nuts respectively are very important.
Villagers living in these zones commonly trade
karuka nuts with those living in the main high-
land valleys between 1400 and 1800 m. The sec-
ond environment where tree crops are particu-
larly important is the highland fringe (600–
1200 m) on the New Guinea mainland. Here the
staple foods include combinations of sago, ba-
nanas and root crops (previously mainly taro but
now sweet potato, Xanthosoma taro and cassava).
These are supplemented by marita pandanus fruit
(Pandanus conoideus), breadfruit seed (but not
flesh), tulip (Gnetum gnemon) leaves and seed
and sometimes castanopsis nuts (Castanopsis
acuminatissima) and sis nuts (Pangium edule).
In the southern part of the New Guinea main-
land, okari nuts are often very important as well.
The third environment in which tree crops,
including nut-bearing species, are particularly
important is small islands. These include those
off the north coasts of New Guinea and New
Britain, those east of New Ireland, the Mussau
Islands (Lepofsky 1992; Kirch 1989) and the is-
lands of Milne Bay Province (MBP). The spe-
cies composition varies between locations, but
the dependence on fruit and nut trees is often
marked (Kirch 1989 p. 226; Yen 1974). For ex-
ample, on Karkar Island the following were very
important food sources (at least until earlier this
century): coconut, galip nut, breadfruit (flesh and
seed), Polynesian chestnut, sea almond, Pouteria
Edible Indigenous Nuts in Papua New Guinea
R. Michael Bourke*
* Department of Human Geography, Research School of
Pacific and Asian Studies, Australian National University,
Canberra ACT 0200, Australia, tel: +61 6 249 2234, fax:
+61 6 249 4896, e-mail: rmbourke@coombs.anu.edu.au
46
Table 1. Edible indigenous nuts in Papua New Guinea. Significance refers to significance in village
agriculture or villagers’ diet
Botanical name Common name Significance
Aleurites moluccana Candle nut minor
Artocarpus altilis Breadfruit very significant
Barringtonia edulis minor
Barringtonia novae-hiberniae minor
Barringtonia procera Cut nut (pao) significant
Buchanania sp. very minor
Canarium acutifolium very minor
Canarium decumannum minor
Canarium indicum Galip very significant
Canarium kaniense very minor
Canarium lamii very minor
Canarium salomonense very minor
Canarium vitiense very minor
Castanopsis acuminatissima important
Cocos nucifera Coconut very significant
Elaeocarpus fagifer minor
Elaeocarpus polydactylus very minor
Elaeocarpus pullenis very minor
Elaeocarpus womersleyi very minor
Finschia chloroxantha Finschia minor
Finschia ferruginiflora very minor
Gnetum gnemon Tulip minor
Heritiera littoralis very minor
Inocarpus fagifer Polynesian chestnut important
Nelumbo nucifera Lotus very minor
Nypa fruticans Nipa minor
Omphalea gageana minor
Pandanus antaresensis Wild karuka minor
Pandanus brosimos Wild karuka significant
Pandanus iwen Wild karuka very minor
Pandanus julianettii Karuka very significant
Pandanus limbatus Wild karuka very minor
Pandanus odoratissima very minor
Pangium edule Sis important
Parartocarpus venenosa very minor
Scleropyrum aurantiacum very minor
Semecarpus (?) cassuvium very minor
Sloanea tieghemii very minor
Sterculia schumanniana very minor
Terminalia catappa Sea almond (talis) important
Terminalia copelandii very minor
Terminalia impediens Okari minor
Terminalia kaernbachii Okari significant
Terminalia megalocarpa Dausia minor
47
maclayana fruit and mon fruit (Dracontomelon
dao) (Allen et al. 1994, p. 50). Villagers on
Karkar say that arable agriculture has become
more important since the adoption of steel tools
some 70 years ago and that fruits and nuts are
now less important in their diet. People on the
nearby islands of Boisa and Manam previously
exported galip nuts to the mainland in exchange
for sago (Allen et al. 1994, pp. 45–48).
In the islands of MBP, fruit and nut tree spe-
cies are very commonly grown, but they have
become less important in peoples’ diets since the
incorporation of sweet potato and cassava into
the agricultural system during this century. Im-
portant species in these islands include coconut,
breadfruit (flesh and seed), Polynesian chestnut,
sea almond, the traditional and introduced mango
(Mangifera minor and M. indica), golden apple
(Spondias cytherea), Pangium edule nuts,
bukabuk fruit (Burckella obovata), Malay apple
(Syzygium malaccense), several Flacourtia fruit
species and dausia nuts (Terminalia megalo-
carpa) (Hide et al. 1994). A similar decline in
the significance of fruit and nut tree crops has
occurred in the Mussau Islands (Lepofsky 1992,
p. 208).
Focus of paper and data sources
The focus for the six species discussed here is
on their distribution within PNG, their signifi-
cance in agricultural systems, the environments
in which the species are grown and the year-to-
year production pattern. The distribution of many
nut species in PNG was previously surprisingly
restricted; that is, some species were grown in
certain regions, but not in other regions with a
similar environment. Over the past 30 years,
some of these species, including okari nut and
cut nut, have been grown more widely within
PNG. Other species, such as karuka, were already
widespread in the environment in which they can
grow.
Information on species distribution is based
on several sources: my observations throughout
most parts of PNG (the small islands off New
Ireland, Manus and Bougainville are the only
significant gap here); recordings made as part of
the project ‘Agricultural Systems of Papua New
Guinea’ and being published as a series of work-
ing papers, for example Allen et al. (1994) and
Hide et al. (1994); and some published sources
including Aburu (1982), Coode (1978), French
(1986), Henty (1982), Hyndman (1984), Jebb
(1992) and Lepofsky (1992). Information on spe-
cies distribution within PNG is still incomplete.
Where available, information is provided on
the physical environment in which each species
is grown. Aspects considered are altitude (tem-
perature), rainfall, habitat and drainage. Soil type
is not mentioned further because it has minimal
influence on a species’ distribution. Soil fertility
and drainage undoubtedly influence the rate of
crop growth and productivity, but information on
this relationship does not exist. Of these physi-
cal factors, altitude (temperature) has the great-
est influence on a species’ distribution. Differ-
ences in altitude as small as 200 m (1°C) may
have a considerable influence on plant distribu-
tion. Data on crop altitudinal range are from
Bourke (in preparation). The altitudinal ranges
given here are mean figures for the usual range;
standard deviations for these figures and extreme
values are given by Bourke (in preparation). In-
formation on production patterns is from a
number of sources collated in Bourke et al.
(1996). These include three to four years of yield
records for experimental plots of galip and okari
nut at Keravat in New Britain; market surveys
and observations on harvesting of karuka nuts
by a network of people at six highland locations
over six to ten years; statements by villagers re-
corded by me; and a literature review for many
locations throughout PNG.
In PNG, seasonal changes in temperature are
small and variable from one year to another. Sea-
sonal temperature differences are negligible
nearer the equator, and greater further from it.
However, even at 10° S in MBP, mean minimum
monthly temperature varies by only 2°C between
the coolest and warmest months. Seasonal rain-
fall changes may be small or great in PNG; they
usually vary from one year to another; and the
seasonal pattern is sometimes reversed over short
distances. For example, the wettest months on
the north coast of New Britain are December to
March, but on the south coast the wettest months
are June to September. Seasonal changes in day
length are small near the equator but increase to
48
about one hour at 9° S; they are constant from
one year to another (McAlpine et al. 1983). These
contrasts in environmental seasonality within
PNG allow some preliminary analysis to be made
on environmental triggers to the flowering of tree
crops.
Six Significant Species
Cut nut (Barringtonia procera)
This species has a remarkably limited distribu-
tion within PNG. It is commonly grown and eaten
on Bougainville Island, New Ireland and the
Gazelle Peninsula of New Britain (but not else-
where in New Britain) (Fig. 1). Jebb (1992) has
reported this species near Madang on the New
Guinea mainland, although all trees that I have
seen on the mainland are recent introductions.
Since 1960 it has been planted at locations on
the north coast of New Guinea and elsewhere in
PNG. The limited distribution in PNG supports
Jebb’s (1992, pp. 177–178) suggestion that this
species is a recent introduction to the Bismarck
Archipelago (New Britain and New Ireland) and
that it originated in the Solomon Islands. Other
edible Barringtonia species (B. edulis and B.
novae-hiberniae) are more widely distributed on
the mainland and other islands, but both are of
only minor importance as food in PNG.
Cut nut is grown from sea level to 500 m alti-
tude, near the coast and in inland locations. These
locations have a rainfall range from 2000 to over
4000 mm a year. Trees are generally planted near
villages, often in open sites. No longitudinal data
on production patterns have been collected and
observations reported by different observers are
conflicting. Production appears to be intermit-
tent throughout the year and non-seasonal, but
more information is required to confirm this. In
the Bismarck Archipelago, cut nut is eaten by
outsiders, including expatriates. This acceptance
suggests that it has good prospects for commer-
cial development.
Galip (Canarium indicum)
Galip is widely distributed in lowland areas on
the northern side of New Guinea and in all is-
land groups (Fig. 1). It is most important on
Karuka (Pandanus julianettii)
Cut nut (Barringtonia procera)
Galip (Canarium indicum)
Figure 1. Geographical distribution of
Barringtonia procera,Canarium
indicum and Pandanus julianettii within
Papua New Guinea
0 200 400
km
MANUS
NEW IRELAND
NEW BRITAIN BOUGAINVILLE
Wewak
Mussau Is
Rabaul
Woodlark Is
Port
Moresby
Lae
Mount Hagen
Karkar Is
0 200 400
km
MANUS
NEW IRELAND
NEW BRITAIN BOUGAINVILLE
Wewak
Mussau Is
Rabaul
Woodlark Is
Port
Moresby
Lae
Mount Hagen
Karkar Is
0 200 400
km
MANUS
NEW IRELAND
NEW BRITAIN BOUGAINVILLE
Wewak
Mussau Is
Rabaul
Woodlark Is
Port
Moresby
Lae
Mount Hagen
Karkar Is
49
Karuka (Pandanus julianettii)
Karuka is very widely planted in a narrow altitudinal
band in the highlands in the central cordillera of
New Guinea and on the Huon Peninsula (Fig. 1).
This species is always planted. A closely related
nut-bearing species (P. brosimos) grows at higher
altitudes (2400–3100 m) and is distributed by ani-
mals, not people. Karuka nuts are an important part
of highlanders’ diets during the producing period.
They provide one of the few high protein plant foods
in this region (Rose 1982). During the harvest, en-
tire households and their domestic pigs may mi-
grate from the main highland valleys up to higher
altitude locations. Tree counts in two villages indi-
cate means of 176 and 12 trees per household
(Bourke 1988, p. 30). However, these villagers’ land
extends just into the altitudinal zones where karuka
grows and much higher tree numbers are likely at
higher altitude locations.
The cultivated species grows at between 1800
and 2600 m and in locations with a mean rainfall
from 2000 to 5000 mm a year. It grows well on
poorly drained sites, for example, near streams and
drainage depressions, but it can also be grown on
better drained sites. It is grown as individual trees
and in large groves in primary forest and in woody
regrowth and cane grass areas originating from
human activity (Stone 1982). It does poorly in open
sites and short grasslands. A preliminary study by
Rose (1982) indicated some genetic differences
between cultivars.
Production is irregular in the western part of the
highlands where rainfall seasonality is slight or
absent. This is illustrated by the data from Wabag,
Mendi, Tari and Oksapmin in Figure 5. In the east-
ern part of the region (Kainantu and Goroka data),
where the rainfall is seasonally distributed, produc-
tion approximates to an annual seasonal pattern;
but there is still large year-to-year variation in the
harvest size. In any year, the producing period also
varies between locations (Fig. 5). After periods of
soil moisture stress or drought, such as occurred in
1979 and 1982, the producing periods coincide at
all or most locations. The biggest harvests follow
major droughts, such as those of 1941, 1965, 1972
and 1982.
Karuka nuts are very popular among the high-
landers and, to a lesser degree, among outsiders.
Unlike galip and some of the other lowland nut
Bougainville, New Britain, New Ireland, the
Mussau Islands, islands off the New Guinea north
coast (such as Karkar, Manam and Vokeo), and
in certain lowland locations on the northern side
of the mainland. It is likely that it was a more
important food before the widespread adoption
of sweet potato, Xanthosoma taro and cassava,
but it is still important in many locations. Pud-
dings made from galip nut, coconut, taro or sago
were made on Bougainville Island. Galip grows
near villages, in woody regrowth after cultiva-
tion and in mature forest. Trees are usually dis-
persed and not grown in groves. Self-sown seed-
lings are protected and trees are planted, often
being selected for desirable characteristics. Many
trees in forest locations are self-sown. Galip
grows from sea level to 700 m altitude and in
locations with a wide range in rainfall (2000–
6000 mm/year). It occurs on both well drained
and poorly drained sites in forested locations, but
is uncommon in grasslands.
The start of the producing period for galip is
fairly constant from year to year for any loca-
tion, and production typically lasts for about three
months (Fig. 3). The production pattern in adja-
cent locations is independent of the rainfall
seasonality. This suggests that flowering is initi-
ated by changes in day length rather than sea-
sonal changes in temperature or rainfall. The start
of the producing period depends on latitude. At
3° to 4° S, it starts in about April. The producing
period starts progressively later at higher latitudes
so that at 10° S it starts in about September. This
relationship is illustrated in Figure 4, using data
from 11 locations in PNG and Solomon Islands.
The relationship appears to hold at locations fur-
ther south outside PNG; for example, on Efate
Island in Vanuatu at 17°30' S, production starts
in October (A. Walter, pers. comm.).
Casual observations and anecdotal evidence,
such as reports of soft-shelled cultivars (Aburu
1982, p. 104), suggest that there is considerable
genetic variation within the species in PNG.
Galip is popular among outsiders, including
expatriates, where it is sold in major urban
markets such as Rabaul and Madang. Prospects
for commercial development are judged to be
excellent.
50
species, most of the available nuts are harvested
and consumed. This suggests that commercialis-
ation could harm the quality of tree owners’ diets.
This aspect requires further investigation before
karuka is developed for commercial production.
This reservation aside, karuka has considerable
potential as a commercial nut within PNG in the
1800–2600 m altitudinal zone, and possibly in other
environments that experience seasonal temperature
differences.
Okari nut (Terminalia kaernbachii)
Okari nut has a limited distribution within PNG. It
is very common in inland lowland locations on the
south side of the central cordillera from the Irian
Jaya border in the west to Mt Dayman in the east
(Fig. 2). It also occurs in a few inland locations on
the northern side of the main ranges; for example,
on the Managalas Plateau in Northern Province and
in the Menyamya–Bulolo area south of the
Markham Valley in Morobe Province. It grows in
West New Britain between the Aria River and Cape
Gloucester, where villagers say that it is a precon-
tact species. On the northern side of the central
cordillera, the closely related nut-bearing
T. impediens occurs, but it is not as common as
T. kaernbachii is on the southern side.
Okari nut does poorly near the ocean and grows
best in inland lowland and intermediate altitude
locations up to an altitude of 1100 m. This may be
because salt air has a negative influence on growth,
but it is more likely to reflect a positive response to
the greater diurnal temperature variation that
occurs away from the moderating influence of the
ocean. Locations where trees are very numerous
and okari nuts are important in villagers’ diets in-
clude the Kiunga–Nigerum region, the Great
Papuan Plateau and the Managalas Plateau. It is
more common on flat and gently sloping land than
on slopes. It appears to tolerate poor drainage and
grows at locations with a wide range in rainfall
(2000–7000 mm a year). It is less common in low-
land locations in Western Province where the rain-
fall exceeds 7000 mm a year, suggesting that pro-
duction may be adversely affected by these extreme
conditions.
The producing period is quite regular from year
to year (Fig. 3) and is independent of rainfall
seasonality. As for galip, there is a close
Sea almond (Terminalia catappa)
Okari (Terminalia kaernbachii)
Polynesian chestnut (Inocarpus fagifer)
Figure 2. Geographical distribution of Terminalia
kaernbachii,Inocarpus fagifer and
Terminalia catappa within Papua New
Guinea
0 200 400
km
MANUS
NEW IRELAND
NEW BRITAIN BOUGAINVILLE
Wewak
Mussau Is
Rabaul
Woodlark Is
Port
Moresby
Lae
Mount Hagen
Karkar Is
0 200 400
km
MANUS
NEW IRELAND
NEW BRITAIN BOUGAINVILLE
Wewak
Mussau Is
Rabaul
Woodlark Is
Port
Moresby
Lae
Mount Hagen
Karkar Is
0 200 400
km
MANUS
NEW IRELAND
NEW BRITAIN BOUGAINVILLE
Wewak
Mussau Is
Rabaul
Woodlark Is
Port
Moresby
Lae
Mount Hagen
Karkar Is
51
Figure 3. Production (kg/ha) of galip and okari at the Lowlands Agricultural Experiment Station, Keravat,
January 1990 to March 1993 (Source: S. Woodhouse, pers. comm.)
Okari nut
Galip nut
120
100
80
60
40
20
0
kg/ha
3000
2500
2000
1500
1000
500
0
Jan
Apr
Jun
Oct
Jan
Apr
Jun
Oct
Jan
Apr
Jun
Oct
Jan
Apr
Jun
Oct
Jan
1990 1991 1992 1993
Jan
Apr
Jun
Oct
Jan
Apr
Jun
Oct
Jan
Apr
Jun
Oct
Jan
Apr
Jun
Oct
Jan
1990 1991 1992 1993
kg/ha
52
Figure 4. Start of the harvesting season (month) of galip and okari nuts at various locations in Papua New
Guinea versus latitude (Source: Bourke et al. 1996)
Okari nut
y = 3.87 + 0.42x
r = 0.576*
Galip nut
12
10
8
6
4
2
00 1 2 3 4 5 6 7 8 9 10
Month
Latitude (degrees S)
12
10
8
6
4
2
00 1 2 3 4 5 6 7 8 9 10
Month
Latitude (degrees S)
y = 1.61 + 0.51x
r = 0.614*
53
production is not strictly seasonal, but further data
are required to test this.
The nut is not popular with people from out-
side the islands where it is commonly grown.
Prospects for commercial development are only
moderate.
Sea almond (Terminalia catappa)
Sea almond is widespread in most coastal regions
of the New Guinea mainland and islands (Fig.
2). It is usually confined to beach areas and vil-
lage sites near the beach, but it occasionally
grows at up to 400 m altitude. Most trees are self-
sown. In most of PNG, nuts are eaten occasion-
ally by children or not at all. However, it is more
important in the islands of MBP where both chil-
dren and adults eat the nuts. One island, Iwa in
the Marshall Bennett Group, is renowned for its
soft-shelled nuts. They are preserved there by
smoking and exported to nearby islands such as
Woodlark. Unfortunately, population pressure on
Iwa is intense, with a population density of more
than 300 people per km2, and fruit and nut trees
are being cleared for arable subsistence agricul-
ture.
The producing period occurs some time be-
tween November and March, with December to
February the most commonly reported period.
The limited available data suggest that the
period is fairly constant from year to year.
Prospects for commercial development are
reasonably good, particularly if cultivars with soft
shells and large kernels are selected.
Acknowledgments
Steve Woodhouse provided unpublished data on
galip and okari nut; numerous observers reported
on karuka production. Patricia Hobsbawn as-
sisted with preparation of this paper. Jean Bourke
and Geoff Humphreys commented on an earlier
draft. Their assistance is acknowledged with
thanks.
relationship between the start of the producing pe-
riod and latitude. For example, production starts in
March or April at 3°–4° S and in June or July at 8°–
9° S (Fig. 4). This suggests that flowering is initi-
ated by seasonal changes in day length rather than
by temperature or rainfall. Trees at Keravat in New
Britain, grown from seed from the Northern Prov-
ince, show large variation in nut and kernel charac-
teristics (Aburu 1982, p. 126).
Okari nuts are popular in Port Moresby and other
urban centres in the producing region. Given the
extensive stands in many locations in southern New
Guinea, it is likely that only a proportion of the
available nuts is consumed by local villagers each
year. Hence prospects for commercial development
from existing trees are very good. Okari nut is now
being grown at locations in PNG distant from its
traditional distribution and there are good prospects
for extending cultivation to other inland lowland
and intermediate altitude locations.
Polynesian chestnut (Inocarpus fagifer)
Polynesian chestnut is widely distributed in the low-
lands on the northern side of New Guinea and on
all island groups (Fig. 2). On the New Guinea main-
land it is usually only of minor significance; it is
more important in the Bismarck Archipelago; and
it is most important on the islands and mainland of
Milne Bay Province. In the MBP islands, it is an
important dietary component during the harvest-
ing season, although it was probably more impor-
tant before the adoption of sweet potato and cas-
sava. It grows from sea level to 500 m altitude in
coastal and near-coastal locations, usually near vil-
lages or in woody regrowth. It also grows in the
foothills on the New Guinea mainland, possibly at
higher altitudes.
In MBP three researchers reported the produc-
ing season from 17 locations as about November
to February, but statements by villagers and re-
searchers about the producing period for other is-
lands in PNG are not consistent. It is possible that
54
Figure 5. Harvesting periods of karuka nut pandanus at six highland locations, 1976 to 1985. (Source: Bourke et al. 1996)
Kainantu
Goroka
Wabag
Mendi
Tari
Oksapmin
J M M J S N J M M J S N J M M J S N J M M J S N J M M J S N J M M J S N J M M J S N J M M J S N J M M J S N J M M J S N
1976 1977 1978 1979 1980 1981 1982 1983 1984 1985
B A S VS B BV VS VB
A S B VS S VB S
B S VB S
BSVBBS
S B ASSBSS SSVB S A
B S B S VS VB VS VS VB B
Observer’s assessment of size of harvest
VB — very big B – big A — average S – small VS – very small Regular observations commenced
55
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