Ice Cream Bean (Inga edulis)

Imagine enjoying the freshly picked fruit of an ice cream bean tree right in your own backyard! This article explains how to grow an ice cream bean tree, and shares interesting facts about this unusual tree.

I. Appearance and Characteristics

Inga edulis, known as ice-cream bean, ice-cream-bean, joaquiniquil, cuaniquil (both from Nahuatl: cuahuxinicuile combining cuahuitl “tree”; icxitl “feet” and necuilli “crooked”) 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, Guyana and Colombia. The taxonomic name Inga is derived from its name with the Tupí people of South America (ingá) while the species name edulis is Latin for “edible”. The common name “ice-cream bean” alludes to 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 caducus.

Inga species are in symbiosis with ants (e.g., Pheidole 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 to 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.

II. How to Grow and Care

Sunlight and Temperature

Ice cream bean trees grow best in full sun, from 8-10 hours per day. The ideal USDA growing zone is 9-11. Growing temperatures should range between 69-82 degrees Fahrenheit.

As far as cold temperatures go, ice cream bean trees will be damaged if the temperatures drop below 30 degrees. Mature in-ground trees may be able to survive a light frost, but temperatures below 28 degrees Fahrenheit can kill them. Protect them as much as possible from cold temperatures.

In cooler weather, the tree will drop its leaves and become semi-deciduous. If your tree is potted, bring it inside near a bright sunny window during the winter.

Watering

Originating from tropical regions, ice-cream-bean thrives in environments with high humidity and consistent moisture. This species exhibits a moderate drought tolerance, maintaining its vitality even when water is less abundant. Watering should occur once every 2-3 weeks to mimic the natural precipitation patterns it’s accustomed to. As an evergreen plant, ice-cream-bean benefits from stable moisture levels year-round, especially important for sustaining its lush foliage whether grown indoors or outdoors.

Soil

Ice cream bean tree is famous as a relative of the legume family for being a nitrogen-fixer. Ice cream beans can be grown in very poor soils, and will actually increase the nutrient content of the soil around them! Leaves that fall or are cut down can be used as a “chop and drop” fertilizer and mulch. Inga grows in soils ranging from poor and sandy soil to rich and loamy, but avoid clay type soils when possible. For a pot, select an organic potting mix that drains well.

Ice cream beans prefer a pH of 5-6.5, but can grow in extremely alkaline or extremely acidic soils if necessary. Aim for a neutral range, but don’t let the soil’s pH prevent you from planting entirely.

Fertilizing

To optimize ice-cream-bean’s health, apply balanced nutrition fertilizers quarterly. These enhance growth, flowering, and fruiting. During the active growth season, increase fertilization frequency to bi-monthly for robust development. Carefully measure based on size and maturity to prevent nutrient burn, and water soil before application to aid nutrient absorption. Tailor fertilizer amounts to ice-cream-bean’s life stage for effective nutrient uptake, and avoid over-fertilizing to maintain plant vigor.

Propagation

Ice-cream-bean is a tropical tree known for its long, seed-filled pods that taste like vanilla ice cream. To propagate this species effectively, one can utilize cuttings, which should be taken from healthy, disease-free parent trees. Cut a semi-hardwood segment, ensuring it contains at least one leaf node. The cutting should be treated with a rooting hormone before being planted in a well-draining soil mixture. Maintain adequate moisture and indirect sunlight to encourage root development, ensuring the medium doesn’t become waterlogged to prevent rot. With proper care, the cutting will establish a robust root system, leading to successful plant growth.

Transplanting

For ice-cream-bean, the pinnacle transplanting time is between late spring to early summer, leveraging optimal growth conditions. Choose a sunny spot with well-draining soil. Gentle handling of roots can enhance establishment in the new location.

Pests and Diseases

Common Pests

Ice cream beans do not have many pests. Strangely enough, they have a symbiotic relationship with some species of ants, and the ants protect the tree against herbivore damage.

The South American fruit fly (Anastrepha fraterculus) can be controlled with cultural practices like removing fallen ripe fruits before resorting to sprays like neem oil. Usually, these don’t go after closed pods, only ones that are broken open on the ground. Removing fallen pods keeps them mostly in check.

The pink hibiscus mealybug (Maconellicoccus hirsutus) can be removed by wiping them off with a damp cloth or a cotton swab dipped in rubbing alcohol. You can also blast them off with a hose or spray with neem oil to smother them.

Common Diseases

Basal rot and other fungi can sometimes cause issues in humid climates, but the tree is very resistant to most diseases, especially when properly cared for. Keep your plants healthy and they should not experience problems from pests or diseases!

III. Uses and Benefits

• Food crop

Inga edulis has been cultivated as a fruit tree for 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 as trypsin and chymotrypsin inhibitors contained in the seeds of Inga edulis are destroyed through cooking.

The taste is described as resembling that of vanilla ice cream. Some varieties even possess a slight cinnamon flavor. The seeds are only edible when cooked and have a taste similar to that of chickpeas.

In Colombia the arils are also used to prepare an alcoholic beverage called 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 extend shelf life to about three weeks.

• Use in agroforestry systems

Due to its rapid growth and ability to improve soil properties, Inga edulis has found widespread use in tropical agroforestry. Most notably, Inga alley cropping is used as an alternative to slash and burn cultivation. It is also a popular shade tree for coffee, cocoa and tea plantations. One important reason for this is that in comparison to other shade tree species Inga edulis retains 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 edulis has not been the object of any improved breeding program. However, the plant has been shown to exhibit strong introgression with Inga ingoides in species contact areas. This could allow for selection of hybrids via interspecific hybridization to further increase yield and flood tolerance of the crop.

• Medicinal uses

Inga edulis is widely used in native South American folk medicine. Decoctions of 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 by herpes. Several studies have investigated Inga edulis as a source of polyphenols for use as antioxidants and have shown promising results. However, further studies are necessary to test and develop medical applications.

IV. Harvesting and Storage

Harvesting

Harvest the pods when they are plump or when they fall to the ground. Inga trees can grow upwards of 60 feet, so you may need to let the ripe fruits fall to the ground or use a fruit picking device. If necessary, you can cut the pod’s stem if it’s clinging to the tree, but usually they become loose when ripe.

Be sure to pick up any remaining pods that have fallen since the seeds inside will quickly germinate.

Storing

The fruit is encased in the hard pods, so this will protect it for up to a week of storage. However, the seeds inside of the pod can sprout quickly, so it’s best to eat ice cream bean when it is ripe. You can also use the pulp to flavor syrups and freeze them for long-term storage, but it’s a very mild flavor.