Inga edulis

Inga edulis known as ice-cream-bean, joaquiniquil, cuaniquil, guama or guaba, is a fruit native to South America. It is in the mimosoid tribe of the legume family Fabaceae. It is widely grown, especially by indigenous Amazonians, for shade, food, timber, medicine, and production of the alcoholic beverage cachiri. It is popular in Peru, Ecuador, Pernambuco-Brazil, Venezuela and Colombia. The name inga is derived from its name with the Tupí people of South America. Its name 'ice cream bean' originates from the sweet flavor and smooth texture of the pulp. Mature trees of Inga edulis reach 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 edulis can 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, evenly pinnate, 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. Extrafloral nectaries are placed on petioles and stipules can be either inconspicuous, absent, or caduceus. It is known that Inga species are in symbiosis with ants (eg. Pheidoles spp.), which get the nectar of the extrafloral nectaries. In exchange the ants will patrol over the Inga plant to protect it against herbivores. There are certain insects such as Riodinid caterpillars 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, corolla with five silky, villous petals. These are around 14–20 mm long and contain numerous white stamens. The fruits are longitudinally ribbed, cylindrical indehiscent leguminous pods 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 10–20, which are purplish-black to olive colored. These are embedded in the sweet, cottony, white arillus which gives it the name Icecream bean, since they taste sweet. SymbiosisThe Inga plant can also form symbiotic relationships where nitrogen gas can be fixated by rhizobial bacteria and mycorrhiza as other legumes can. Surveys have shown that Inga edulis undergo a mutualistic relationships with the bacterial strain of Bradyrhizobium. This plant has a convoluted history of synonymy with Inga vera. The plants discussed under that name by Brenan and Kunth are actually I. edulis, whereas that based on the writings of Carl Ludwig Willdenow refers to the actual I. vera. Inga edulis in works referring back to authorities other than von Martius usually refers to Inga feuilleei. Synonyms of Inga edulis Mart.: The natural distribution of Inga edulis spreads from Central to South America and ranges from subtropical dry to tropical wet conditions. It can be found at elevations from sea level up to 2200 m. Inga edulis grows 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. Preferred annual precipitation ranges from 1200 to 2500 mm but 640 to 4000 mm of annual precipitation can be tolerated also. Inga edulis can be grown on a widely varying range of soil conditions. It prefers a soil pH of 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 of Inga edulis includes margins of large rivers like the Amazon, 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. Further Inga edulis can cope with heavy soils or slope fairly well. In terms of soil fertility, Inga edulis is not only unpretentious but has the potential to improve soil quality. As a leguminous tree, Inga edulis can compensate for nutrient depleted soils by fixing nitrogen with 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 benefit Inga edulis and continued to show properties that prevented nodulation. Additionally to nitrogen, Inga edulis is reported to significantly increase the extractable Phosphorus content in the soil and thus further ameliorates degraded soils. Inga edulis is widely cultivated in agroforestry systems in its neotropical dispersal area. This form of cultivation, often associated with coffee or cocoa culture is widely known since pre-Columbian times. Germination of Inga edulis seeds 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 decrease competition with noxious weeds and thus increase growth. Further, the inoculation with rhizobia and mycorrhizal fungi in depleated 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 edulis seems to be very resistant to pests and diseases. Minor damages can result of fungal attacks in the seedling stage. Mature Inga edulis can be defoliated by Lepidoptera larvae. Also, fruit fly larvae often damage the seed testa. In Ecuador, Inga edulis in specially susceptible to mistletoe infestations. Food crop