Agroforestree Database

Local names:
 English (ice-cream bean tree), French (pois sucre,ingá), Portuguese (inga-de-metro,inga-cipo,cajasciro), Spanish (rabo de mico,inga,huaba,guano,guamo bejuco,guabo,guaba), Trade name (guaba)

Inga edulis mature trees reach 30 m high and 60 cm diameter at breast height, usually branching from below 3 m. The branches form a broad, flat, moderately dense canopy. The bark is pale grey and smooth with pale elongated lenticels. The young twigs are angular in cross-section and covered with fine short hairs.

Leaves, once-pinnate, up to 24 cm long, with 4-6 pairs of opposite leaflets. The terminal pair of leaflets is larger than the basal pair and can be up to 18 cm long and 11 cm wide. Between each leaflet there is a nectary gland on the leaf rachis. The seedlings have a characteristic greyish sheen on the upper leaf surface.

Inflorescence in dense axillary spikes of flowers, each consisting of a calyx tube with 5 lobes, a corolla tube with 5 lobes, and a large number of white stamens up to 4.5 cm long, united in a tube in the lower half.

Fruits ribbed, cylindrical pods, straight or often spirally twisted, up to 1 m long. They contain fleshy green seeds in a sweet, white, cottony pulp. They are produced during the wet season, and monkeys and birds eat the sweet pulp and scatter the soft seeds.

The name ‘inga’ is derived from its name with the Tupi Indians of South America. The specific name, ‘edulis’, means edible.

Ecology

I. edulis grows rapidly on the poorest Exisols and can also be found on floodplains that are waterlogged for 2-3 months each year. Although generally associated with warm, lowland, wet tropics, it is also remarkably resistant to drought and cold, occurring in regions with a 6-month drought. It is a light-demanding gap species of lowland rain forest, where it becomes a large tree, and it is also found in riparian situations.

Native range
Bolivia, Brazil, Colombia, Ecuador, Peru

Tree management

An area 1 m in diameter should be kept clear around the tree for the 1st 6 months of growth. I. edulis grows back well after pruning, but not if cut below 0.75 m. There is a better response if pruning height is varied and a few branches are left uncut. The cut should be made carefully, at least 3 cm above a node from which the shoots can grow again.

The seeds are recalcitrant and sometimes begin to germinate in the pod, often within a few days of reaching the ground, where they need moisture to survive. The seeds can be stored for only 2 weeks. Best results have been achieved by removing the pulp and storing the seed in impermeable bags.

I. edulis grows rapidly on the poorest Exisols and can also be found on floodplains that are waterlogged for 2-3 months each year. Although generally associated with warm, lowland, wet tropics, it is also remarkably resistant to drought and cold, occurring in regions with a 6-month drought. It is a light-demanding gap species of lowland rain forest, where it becomes a large tree, and it is also found in riparian situations.

Farmers sometimes sow I. edulis seeds directly in the field. This must be during a season of regular rainfall to avoid seed desiccation. Direct sowing has not proven to be a reliable method for establishing the species. Normally, only 1 seed should be sown in a plastic bag, no more than 2 cm below the soil surface. Semi-shade should be provided, if possible. The seeds germinate readily (95-100% germination rate) in 2-3 days. Seedlings are normally kept in the nursery for 2-3 months. They should be watered regularly, and the shade should be removed 1 month before transplanting. Bare-root seedlings can successfully be transplanted directly from the nursery.

In trial experiments on cultivated slopes, I. edulis mulch reduced soil erosion to levels almost equal to those in secondary forests.

 The large fruit is popular in all the regions where I. edulis is grown. In Bolivia, Brazil, Costa Rica and Ecuador, they are sold in the marketplace.

Fodder: Pigs eat seeds when hungry, and cattle will even eat whole pods and leaves.

The ease with which the seed germinates, its quick growth, rusticity and high coppicing ability make this species useful for the smallholder’s woodlot and it is also a useful bush-fallow species. The branches are a popular source of firewood, with a high calorific value and little smoke, although the tree is not cultivated specifically for fuel.

Shade or shelter: I. edulis has been used as a shade tree for perennial crops, mainly coffee and cacao since the beginning of the 19th century. The open crown and rapid growth provide excellent shade, and trees are widely used for this purpose around dwel

Nitrogen fixing: Due to its nitrogen-fixation ability, I. edulis has been employed in improved fallows.

Soil improver: The litter is high in nitrogen, lignins and polyphenols. It is slow to decompose, but provides a long-term build up of organic nitrogen and effective weed control. Weed biomass decreased considerably in all agroforestry trials with I. edulis, much more than with other leguminous species. Existing trials are too new to ascertain whether the species can maintain or improve soil fertility on acid sites in the long term, but results so far are promising.