Inga edulis

Inga edulis, known asice-cream bean,ice-cream-bean,joaquiniquil,cuaniquil(both fromNahuatl:cuahuxinicuilecombiningcuahuitl"tree";icxitl"feet" andnecuilli"crooked")guamaorguaba, is a fruit native toSouth America. It is in themimosoid tribeof the legume familyFabaceae.It is widely grown, especially byIndigenousAmazonians, for shade, food, timber, medicine, and production of the alcoholic beveragecachiri. It is popular inPeru,Ecuador,Pernambuco-Brazil,Venezuela, GuyanaandColombia.The taxonomic nameIngais derived from its name with theTupí peopleof South America (ingá) while the species nameedulisis Latin for "edible". The common name "ice-cream bean" alludes to the sweet flavor and smooth texture of the pulp.
Mature trees ofInga edulisreach 30 m (98 ft) high and 60 cm (2.0 ft) diameter at breast height, usually branching from below 3 m (9.8 ft). The branches form a broad, flat, moderately dense canopy.Inga eduliscan be evergreen in tropical regions or deciduous when planted in colder regions. The tree has a pale grey coloured trunk. The stems and young twigs can be sparsely to densely haired. The leaves are alternate, evenlypinnate, 10–30 cm long with 4–6 pairs of opposite, dark-green, membranous, slightly pubescent, oval leaflets. The terminal leaflets can grow up to 18 cm long by 11 cm wide in comparison to the basal ones. Extrafloralnectariesare placed onpetiolesandstipulescan be either inconspicuous, absent, or caducus.
Inga species are in symbiosis with ants (e.g.,Pheidolespp.), which get the nectar of the extrafloral nectaries. In exchange the ants will patrol over the Inga plant to protect it againstherbivores. There are certain insects such asRiodinidcaterpillars which excrete sugary honeydew from their tentacle nectaries. The ants will form a symbiosis with the caterpillars by letting them feed on the tree and in favour of getting sugary honeydew from them.Flowers are fragrant, sessile, pentamerous and are arranged in dense axillary spikes. The flower has a calyx tube with five puberulent, striate lobes,corollawith five silky, villous petals. These are around 14–20 mm long and contain numerous whitestamens. The fruits are longitudinally ribbed, cylindrical indehiscentleguminouspods which can be straight, curved or often spirally twisted up. They are pendant and up to 1 m long and yellowish brown to greenly coloured. The amount of ovoid seeds can vary from 10 to 20, which are purplish-black to olive colored. These are embedded in the sweet, cottony, whitearilluswhich gives it the name Icecream bean, since they taste sweet.
This plant has a convoluted history ofsynonymywithInga vera. The plants discussed under that name byBrenanandKunthare actuallyI. edulis, whereas that based on the writings ofCarl Ludwig Willdenowrefers to the actualI. vera.Inga edulisin works referring back to authorities other thanvon Martiususually refers toInga feuilleei.
Synonyms ofInga edulisMart.:
The natural distribution ofInga edulisspreads fromCentraltoSouth Americaand ranges from subtropical dry to tropical wet conditions.It can be found at elevations from sea level up to 2200 m.Inga edulisgrows best when mean annual daytime temperature ranges from 23 to 30 °C. However, it can tolerate 18–35 °C. During the resting period mature trees can survive −2 °C while young plants are killed at 0 °C. Preferredannual precipitationranges from 1200 to 2500 mm but 640 to 4000 mm of annual precipitation can be tolerated also.Inga eduliscan be grown on a widely varying range of soil conditions. It prefers asoil pHof 5–6.5 but can also grow in very strongly acidic soil down to a pH of 4.5 or moderately alkaline conditions up to pH 8.The natural habitat ofInga edulisincludes margins of large rivers like theAmazon, thickets below high water line and wooded swamps.Therefore, the tree tolerates temporarily waterlogged soils for 2–3 months each year. However, it can also tolerate drought seasons up to 6 months.FurtherInga eduliscan cope with heavy soils or slope fairly well.In terms of soil fertility,Inga edulisis not only unpretentious but has the potential to improvesoil quality. As aleguminous tree,Inga eduliscan compensate for nutrient depleted soils byfixing nitrogenwith its root nodules. Ammonium and nitrates found in soil typically result in nodulation reduction.Inga edulis is an exception, as its nodules increase in size when ammonium levels are at 5mM. Nitrate on the other hand did not benefitInga edulisand continued to show properties that prevented nodulation. Additionally to nitrogen,Inga edulisis reported to significantly increase the extractablePhosphoruscontent in the soil and thus further ameliorates degraded soils.
Inga edulisis widely cultivated inagroforestrysystems in itsneotropicaldispersal area. This form of cultivation, often associated withcoffeeorcocoaculture, is widely known sincepre-Columbiantimes.GerminationofInga edulisseeds is fairly easy as the seeds are recalcitrant and often germinate already in the pod. However, seeds lose their ability to germinate after two weeks of storage.Direct sowing of the seeds is possible, but the establishment of seedlings with already a certain height can decreasecompetitionwith noxious weeds and thus increase growth.Further, the inoculation withrhizobiaandmycorrhizalfungi in depleted soils is recommended to promote growth.These inoculi can easily be produced by collecting soil, nodules and fine roots from mature, nodulated inga edulis stands.Inga edulisseems to be very resistant to pests and diseases. Minor damages can result of fungal attacks in the seedling stage. MatureInga eduliscan be defoliated byLepidopteralarvae. Also, fruit fly larvae often damage the seed testa. InEcuador, Inga edulis is specially susceptible tomistletoeinfestations.
Food crop
Inga edulishas been cultivated as afruit treefor millennia and is widely sold on the local South American marketplace, mainly for the sweet, succulent pulp surrounding the seeds. The white pulp (aril) is consumed raw as a sweet snack, though it is less nutritious than the seeds. Toxic compounds such astrypsinandchymotrypsininhibitors contained in the seeds ofInga edulisare destroyed through cooking.
The taste is described as resembling that ofvanilla ice cream.Some varieties even possess a slight cinnamon flavor.The seeds are only edible when cooked and have a taste similar to that ofchickpeas.
InColombiathearilsare also used to prepare analcoholic beveragecalled cachiri for a festival of the same name. The native women chew the arils and spit the mixture into a vat, where it is left to ferment.The fruit ripens quickly and can only be kept for three to four days, limiting potential export opportunities. However, refrigeration can extendshelf lifeto about three weeks.
Use in agroforestry systems
Due to its rapid growth and ability to improve soil properties,Inga edulishas found widespread use in tropicalagroforestry. Most notably,Inga alley croppingis used as an alternative toslash and burn cultivation. It is also a popular shade tree forcoffee,cocoaandteaplantations. One important reason for this is that in comparison to othershade treespeciesInga edulisretains its leaves in the dry season.Cuttings and leaves also used as mulch and animal fodder.The wood is sometimes used as timber and for fuel, its popularity as a source of firewood stemming from its high calorific value and weak smoke production.
Despite its rapid growth and significant potential to improve soils in agroforestry systems,Inga edulishas not been the object of any improved breeding program.However, the plant has been shown to exhibit strongintrogressionwithInga ingoidesin species contact areas. This could allow for selection of hybrids via interspecifichybridizationto further increase yield and flood tolerance of the crop.
Medicinal uses
Inga edulisis widely used in native South American folk medicine.Decoctionsof the leaves, bark or root commonly are utilized as treatments for diarrhea, arthritis and rheumatism.Crushed, boiled leaves are ingested to relieve coughing or applied to lip sores, possibly caused byherpes.Several studies have investigatedInga edulisas a source ofpolyphenolsfor use asantioxidantsand have shown promising results.However, further studies are necessary to test and develop medical applications.
Ice Cream Beans