HUANACAXTLE: CHARACTERISTICS, TAXONOMY, HABITAT, USES - BIOLOGY - 2025

The huanacaxtle (Enterolobium cyclocarpum) is a large timber tree species that belongs to the Fabaceae family. Known as carocaro, conacaste, corotú, guanacaste, guanacastle, rattle, parota or ear pinion, it is native to the deciduous tropical forests of Central America.

It is considered an endemic species in Mexico and some dry areas of the Pacific slope in Central America, South America and the Antilles. In fact, it is appreciated for its large size and enormous biomass, being used for its phytochemical, ecological, food, agro-industrial and medicinal properties.

The huanacaxtle (Enterolobium cyclocarpum). Source: Flicka

This tree grows in open spaces, reaches 40-45 m in height and has a short and thick trunk 3 m in diameter. Likewise, it has numerous ramifications that support a large volume of bipinnate leaves, its ear-shaped fruit being particular.

The adult huanacaxtle trees are a valuable source of wood used for carpentry, joinery and construction. In addition, the branches are raw material for combustion. In some regions, the viscous pulp of the pods is used for the production of artisan soap and the fruits constitute a nutritional supplement for livestock.

From the ecological point of view, this species has the particularity of creating symbiotic associations with the endomycorrhiza of the soil. This favors the absorption of mineral elements from the soil, as well as nitrogen fixation through nodulation with the rhizobia around the roots.

General characteristics

Morphology

- Species: Enterolobium cyclocarpum (Jacq.) Griseb. 1860.

Etymology

- Enterolobium derives from the Greek words entero which means intestine and lobe lobe, alluding to the shape of the fruits.

- The specific adjective cyclocarpum comes from kyklos which means circle and karpos of fruit, also related to the shape of the fruit.

- The common name guanacaste, guanacastle or huanacaxtle comes from the Nahuatl quauh which means tree and nacastl ear -fruit shaped like an ear-.

Habitat and distribution

The huanacaxtle is a wild species native to Mexico, Central America and the northern part of South America. It is a tall tree that grows along water courses, rivers or streams, and along coastal areas.

Huanacaxtle flowers. Source: Dick Culbert from Gibsons, BC, Canada

In Mexico it has great geographic versatility and is located along the slopes of the Gulf of Mexico and the Pacific Ocean. Through the Gulf from the southern region of Tamaulipas to the Yucatan Peninsula; through the Pacific along Sinaloa to Chiapas.

Its natural habitat is located below 500 meters above sea level. In addition, it adapts to dark, sandy and clayey soils, particularly in vertisols of the Pelic and Gleyco type, of medium fertility and slow drainage.

Applications

Edible

Huanacaxtle seeds are an excellent nutritional resource due to their high content of amino acids, proteins (32-41%), minerals (calcium, iron and phosphorus) and vitamins (250 mg of Ascorbic Acid). The nutritional value of the seeds of this species is comparable to wheat or fish flour.

The seeds are consumed roasted, being as nutritious as the seeds of the Fabaceae (beans). In some localities, roasted seeds are an alternative substitute for coffee, and can also be consumed in soups, dressings or sauce.

Timber

The huanacaxtle wood is light and resistant, reddish in color, diffuse grain and interlaced grain, highly resistant to water and insect attack. It is used in joinery and carpentry in general, in the manufacture of furniture, interior finishes, boats and canoes.

Also, in panels, laminations, sheets, plywood, staves, carts, wheels and as sawdust. However, the slightly pungent, strong-smelling powder is usually allergic to some people.

In some areas, wood is used in a traditional way to make turned items, kitchen utensils, ornaments or toys. Similarly, wood is used in rural buildings or for the manufacture of agricultural implements.

Huanacaxtle trunk. Source: © Tomas Castelazo, www.tomascastelazo.com / Wikimedia Commons

Fuel

The fruits of the huanacaxtle contain a gummy resin that, mixed with the macerated pulp of the fruit, is used to manufacture coal agglomerates. In addition, the firewood of this species has a high caloric level, being an excellent source of energy for rural areas.

Medicinal

The content of various secondary metabolites (alkaloids, flavonoids, phenols, tannins) in the bark, root and fruit favor the medicinal properties of huanacaxtle. The tea from the bark or pods is used to relieve discomfort caused by rashes or skin conditions, as well as cleansing.

The trunk exudes a resin called "expensive gum", used as a home remedy for the common cold and bronchitis. The immature fruits are astringent and are used to calm diarrhea; the root is used as a natural blood cleanser.

Forage

The tender stems, leaves, fruits and seeds are used as a food supplement for grazing or corral animals. The high protein content, greater than 36%, favors its use as a nutritional supplement for cattle, horses, goats and pigs.

It is supplied to livestock as cut feed or by browsing young plants. However, due to the height of the adult plants, it is not very popular with livestock.

Others

The high content of tannins in the resin exuded by the bark, fruits and seeds is used in the tanning of hides. The pulp of the immature pods emanates saponins that are used to make handmade soap.

On the other hand, the mucilage or gum that exudes the bark is often used as a substitute for gum arabic. In the flowering season, the huanacaxtle generates an abundant flowering that attracts a large number of pollinating insects, being an excellent melliferous.

Immature fruits of the huanacaxtle. Source: Forest & Kim Starr

Spread

Seed preparation

The huanacaxtle tree starts the production of seeds after 15-25 years, producing more than 2,000 pods annually. Indeed, each pod contains 10-16 seeds, which are perfectly viable once harvested during the dry season.

The large, hard seeds with a thick covering are extracted from the indehiscent pods by physical means, either by crushing or sifting. One kg of seeds contains from 800 to 2,000 seeds, which require a pre-germination treatment to achieve germination in suitable environmental conditions.

In this regard, hot water, sulfuric acid or a mechanical method, such as manual scarification, can be applied, which is cumbersome for large batches. For large quantities of seeds, they are soaked for 30 seconds in boiling water, and then kept in cool water for 24 hours.

Sowing

The seeds are placed on a fertile substrate in polyethylene bags, at a depth of 1-2 cm, trying to place the micropyle towards the bottom. It is necessary to maintain continuous watering to achieve germination 3-4 days after sowing.

The huanacaxtle has a fast and vigorous initial growth. In nursery it requires abundant watering, but little shade to be ready after 3 months. In fact, when the seedlings reach 20-25 cm in height they are ready to transplant to the definitive field.

Transplant

The structure of the huanacaxtle tree limits in some way the establishment of commercial plantations or pure stands. It is advisable to plant 3 × 3 or 4 × 4 m, carrying out maintenance pruning to mold the size and shape of the crown.

Agronomic management

During the establishment of the plantation a constant supply of humidity and periodic weeding around the plant is required. In commercial plantings, maintenance pruning is frequent to prevent the branches from spreading disorderly.

Huanacaxtle tree in bloom. Source: Forest & Kim Starr

Development and production

Trees in open spaces, grasslands, or along roadsides grow faster than commercially established plantations. In fact, in plantations the initial growth is slow, but it increases when the tree acquires a dominant position.

It is common for a huanacaxtle specimen at 8 years to reach 8-15 m in height and 8-12 cm in diameter. However, individuals grown in open conditions can reach up to 10 cm in diameter at chest height annually.

At 25 years of age, a huanacaxtle tree is considered an adult, exhibiting an average of 18 m in height and 42-45 cm in diameter. From this stage, flowering occurs during the first months of the year, and the fruits ripen one year after flowering.

References

1. Conacaste Tree (Enterolobium cyclocarpum) (2018) Foundation for Socioeconomic Development and Environmental Restoration. Recovered at: fundesyram.info
2. Enterolobium cyclocarpum. (2019). Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org
3. Enterolobium cyclocarpum (2018) National Forest Information System. CONAFOR - National Forestry Commission. 8 pp.
4. Francis, John K. (1988) Enterolobium cyclocarpum (Jacq.) Griseb. Tropical Tree Seed Manual. 5 pp.
5. Guanacaste, Pich, Parota, Oreja de negro (2017) Mexican Biodiversity. National Commission for the Knowledge and Use of Biodiversity - Conabio. Recovered in: biodiversity.gob.mx
6. Pineda Melgar, O. (2018) Conacaste (Enterolobium cyclocarpum), a multi-use tree in tropical regions of Guatemala. Engormix. Recovered at: engormix.com
7. Quezada Bonilla, JB, Garmendia Zapata, M., & Khiem Meyrat, A. (2010). Arboreal species of the Alain Meyrat arboretum. National Agrarian University.
8. Serratos Arévalo, JC, Carreón Amaya, J., Castañeda Vázquez, H., Garzón De la Mora, P. & García Estrada, J. (2008). Chemical-nutritional composition and antinutritional factors in parota seeds (enterolobium cyclocarpum). Interciencia, 33 (11), 850-854.