Inga edulis
Family: Leguminosae subfamily Mimosoideae
Botanical: Inga edulis Mart.
Vernacular: Inga (Brazil); ice-cream bean (W. Indies); guabo (Peru); pois sucre (French Guyana); guano (Costa. Rica).
Ecology and Distribution
Inga edulis grows rapidly on the poorest of oxisols and can also be found on floodplains that are water-logged for 2 to 3 months each year.
Although
generally associated with the warm, lowland, wet tropics, it is also
remarkably resistant to drought and cold, occurring in regions with a 6
month drought and at altitudes of 1500 m in the Andes.
The
species originated in tropical Latin America and is now very widely
distributed throughout this region and also in Central America and the
West Indies.
It is frequently found in and around small dwellings in these regions.
Related species: Inga alba (Sw.) Willd., I. coriacer (Pers.) Desv., I. cinnamomea Spruce ex Benth, I. fagifolia (L.) Willd., I. falcistipula Ducke, I. heterophylla Willd., I. macrophyla H.B.K., I. thibandiana DC, I. velutina Willd., I. densiflora, I. feuillei, I. jinicuil, I. paterno and 100 or more wild species of Inga are found in central and southern tropical America.
Description
A
fast growing, evergreen forest tree 10-15 m high, with open, much
branched crown often as wide as the height, and usually branching from
just above ground level; bark thin, brownish-grey, slightly rough, pink
within; seedlings with well-developed taproots.
Leaves
alternate, compound, pinnate; stipules awl-shaped, 1-2 mm long, soon
falling; rachis 20-50 cm long, conspicuously and broadly winged between
the leaflets and with a circular, cup-shaped, nectarial gland 2 mm in
diameter on the upper side of the rachis between the point of
attachment of each pair of leaflets; leaflets opposite, 4-6 pairs,
elliptic to elliptic-oblong, 5-15 cm long, 2-8 cm wide, apex often long
acuminate, base rounded to truncate or weakly cordate, margins often
slightly undulate, sparsely pilose, smooth, mid-green above, slightly
rough and paler below, midrib and veins often densely hairy and very
prominent below.
Inflorescence 1 or more axillary, short spikes
3-6 cm long; flowers sessile, bisexual. Calyx tubular, 4-7 cm long,
greenish, hairy outside, with 5 deltoid teeth; corolla greenish-white,
tubular, 10-15 mm long, with 5 deltoid teeth, hairy outside; stamens c.
80, with slender filaments exserted 20-40 mm beyond the corolla tube;
carpel 1, ovules numerous.
Fruit a cylindrical pod 50-100 cm
long, 3-4cmin diameter, shortly tomentose and with severely very deep
longitudinal grooves, twisting and indehiscent; seeds 10-20, purple to
black, 3-4cm long, 1.5-2 cm wide, with a thin testa and embedded in a
sweet, white, fibrous pulp 0.5cm thick.
Flowering and fruiting
2-3 times every year, at different times on different trees; the ripe
pods, which take 3 months to develop, being available from September to
June.
Main Uses
The succulent testas are eaten off the seeds
after removing them from the softened pod by twisting it open. The
testas are sweet and soft but very full of fine fibres. They remind one
of eating cotton wood soaked in sugar and it is consequently surprising
that they are so popular.
Lightly cinnamon flavoured varieties have been noted and these are considerably more attractive.
Seeds are too bitter to eat although those of I. paterno are said to be eaten roasted in El Salvador. Pigs eat seeds when hungry and cattle will even eat whole pods and leaves.
The trees grow extremely fast and provide a lightwood (0.3 to 0.4 g/cm3)
that is frequently used for fuel. The open crown and rapid growth also
provides an excellent shade and trees are widely used for this purpose
around dwellings and in cocoa and coffee plantations.
Method of Collection of the Edible Part
Pods
are either pulled off lower, or cut off higher branches when thick and
soft. They may also yellow slightly at this stage. Pods will keep for
almost a week after harvest and are easily carried.
A tree with a 10 m crown will produce 20 to 100 pods at least twice a year.
Nutritional Value
The
testas are usually much heavier than the seeds but are over 70%
water. The remaining dry matter is largely sugar and fibre. Brix levels
up to 25% have been recorded so the sugar provides a useful amount of
calories.
The seed has 17% protein in its dry matter so may be a useful feed for pigs.
Cultivation and Propagation Methods
Seeds
have usually started to germinate within the pods when the testas are
ripe to eat. They are very hardy and root easily when thrown on top of
moist soil. Thus most trees around dwellings have probably not been
planted.
They nodulate very well with nodules of over a
centimetre being common. Growth is extremely rapid with branching
occurring just above the ground to give a very open and untidy crown.
Trees
can reach a height of 5 metres in two years and will fruit soon after
the first year in favourable conditions. They are short lived (20
years), frequently showing rotting in branches over 15 cm in diameter.
Regrowth
of cut trees is extremely vigorous reaching 4 metres in one year.
Although trees are resistant to leaf cutting ants, complete defoliation
by Lepidooteran larvae has been seen.
Fruit fly larvae often
damage testas especially in late maturity. Slight damage from fungal
attack (Rhizoctonia) of seedlings has been noticed, otherwise the trees
seem very healthy.
Potential Economic Importance
Fruit are
frequently seen in local markets where they are low priced and well
appreciated. Easy transport and storage are also important factors as
the flavour is not attractive enough to justify commercial plantations.
They
are important economically as shade trees and supports in cocoa, coffee
and vanilla plantations. The advantages of direct planting in the
field, resistance to climatic extremes, pests and disease, very fast
growth and regrowth and nodulation also make them an interesting option
for woodlots, agroforestry systems and useful bush fallows.
Biomass yields superior to those of Eucalyptus deglupta and Leucaena spp. seem probable on poor exisols when all these factors are considered.
There
is thus an urgent need to select varieties or species in the same genus
for better form to awaken the interest of foresters. Cinnamon flavoured
fruit and edible seeds should also be selected for.
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