Pentaclethera macrolobaOil Bean Tree
Spanish Name: Palo de aceite
Familiy Fabaceae
Subfamily: Mimosoideae Tribus: P
Me and a little Oil Bean
Genus: Pentaclethera Species:
Pentaclethra macroloba
Range and Abundance:
P. macroloba is a lowland species that is primarily located in humid tropical forests and in most cases is the dominant canopy tree often found growing on a moderate slope tviewer.pngypically near swampy areas or rivers. The oil bean tree has some biological limits to growth. These conditions include an altitude between 0-600 m, a mean annual temperature of 20-35 degrees Celsius, light to heavy acidic soils, an over 2500 mm of annual rainfall. The documented species distribution of native P. macroloba trees is; Brazil, Colombia, Costa Rica, Cuba, Guyana, Honduras, Jamaica, Nicaragua, Panama, Peru, Surinam, Trinidad and Tobago, and Venezuela. The species is exotically present within the Congo. Within La Selva, this tree was by and far the most abundant canopy species.
Oil Bean Tree Seedlings at La Selva
P. macroloba is a very fast growing emergent tree that dominates the canopy of tropical forests. At La Selva Biological station the tree has an importance value (percentage of total basal area) twice that of the next highest tree species (Bennett, B. et. al. 1985). The tree averages 30-35 meters in
Oil Bean Tree Leaves at La Selva
height and typically has a diameter of 130 centimeters. The bole of the tree is cylindirical and the base and when it grows in areas of flooded forest it develops small buttresses (Longino 2005). The foliage is feathered and the branches are rough and strong. The bark is a grayish brown color and is smooth. The leaves are long, shiny, biparipinnate (two leaflets on either side), stipulate (contains outgrowth on branches), and have small structures on the distal end of the leaf. Costa Rican P. macroloba show some different characteristics than trees found in other locations. Coast Rican trees are taller and the bore holes do not bear branches, the wood is also darker and of higher quality. The tree wood is usually very conservable as it can resist all forms
Oil Bean Tree at La Selva
of subterranean termites for 6-7 years. (Flores, E.M. 1994)

Flowering and Fruiting and Seeds:
The oil bean tree typically flowers and fruits in 1 to 2 years. The species blooms from April to August but flowers are seen throughout the entire rainy season. Flower stalks contain many individual flowers (200+ per stem) but few individual fruits actually are formed. Flowers are bisexual and monomorphic and are typically found clustered together on the branches. The main fruit crop appears in August and September with other secondary fruit harvests taking place in other months. The fruit is a pod that is about 25 cm long and about 4-6 cm wide. Each pod contains about 3-8 s
A P. Macroloba Tree, fruit and Pod
eeds. Pod dispersal is explosive in order to distribute the seedlings. Seeds are brown and dull and are classified as overgrown because its growth is limited by pod size. Seed germination averages about 90 percent and the seeds have a very high lipid concentration that has industrial potential (Wright The seeds are shade tolerant and germinate very well in the forest. The juveniles grow slowly during the first two years but all types survive under the canopy until maturation and rapid growth.

Ecology and Interactions:
P. macroloba is a tree species that is found commonly within tropical forests and is a pioneer in the regeneration of previously disturbed areas (Oberbauer et. al. 1986). This carrying capacity is explained by nitrogen fixing through root nodules and a series of accessory buds that are able to replaced the damaged main shoot. These characteristics give the species the ability to naturally regenerate itself and help
Me and a Big Oil Bean Tree
restore a previously destroyed or disturbed forest. The oil bean tree is also very important to a certain species of ant,
Paraponera clavata. A definite association between the ant and the tree have been observed by several investigators (Fuller et. al. 1982) and has been further tested since to see if any actual relationship stands. While it is noted by many other scientists that the relationship is true, one report (Bennett and Breed 1985) suggest that the relationship may not be as strong. After testing the sites of the ants at La Selva the researches determined that the two species are weakly associated. They noted that the buttresses of the P. macroloba tree may afford a suitable nesting habitat and that the trees location may be a nesting site near a fo
Oil Bean Tree Flanks the Bridge
od resources. So while it is not conclusive that
P. macroloba is distinctively related to this species of ant, some of the qualities that make the tree a suitable nesting site for other living organisms is seen in the study. The experiment also suggested a symbiotic relationship between the two where the tree provides shelter or food and the ant claims other insect predators. In Costa Rica, the main pest predator is Sematura luna a species that belongs in a subfamily of moths.
Sematura luna
The tree is very susceptible to insect predation which is expected since insects are the primary pollinators of the seeds. The other main predator to the tree is man which uses almost all of the tree for industrial uses. The seeds are edible and are used to produce a cooking oil that is widely used in Africa
Owala oil from P. Marcoloba
.The wood is used typically as a fuel for fire and since the wood is hard, sturdy, rough, and strong it is commonly used as a replacement for mahogany. Interestingly enough the seeds contain a toxin that may cause allergic reactions in some humans. Becasse of this toxicity monkies and birds generally avoid habitating the trees. Finally, the seeds have many medicinal usages including remedies against snake bites, ulcers, insect bites.
Oil Bean Tree at La Selva
The bark is also used to cure dysentery.
Observations at La Selva: Pentaclthera macroloba is absolutely everywhere at La Selva. It is difficult to travel even 50 meters without seeing some seedlings or a very large Oil Bean Tree. As literature cited, this tree contains toxins that cause many of animals to avoid the tree. Data observations out in La Selva prove this to be true as I did not see a single animal located on or around a Pentaclethera macroloba tree.


Bennett, B. and M. D. Breed. 1985. On the association between Pentaclethra macroloba (Mimosaceae) and Paraponera clavata (Hymenoptera: Formicidae) colonies. Biotropica 17:253–255.

Dyer, L.A. 2002. A quantification of predation rates, indirect positive effects on plants, and foraging variation of the giant tropical ant, Paraponera clavata. 7pp.
Journal of Insect Science, 2:18. Available online:

Fuller, M, L. Higging, M. L. Higgins, B Milligan, v Terwilliger, and S. Werman. 1982 Comments on the abundance of
Paraponera and their association with Pentaclethera macroloba. OTS Tropical Biology Coursebook, 1981-3, pp. 82-83. OTS, San Jose, Costa Rica.

Flores, E. M.
Pentaclthera macroloba. Academia Nacional de Ciencias de Costa Rica, Costa Rica. Pp. 601-604. 1994.

Longino, John T. "Collection Data for ALAS La Selva Samples."
Academic Program Pages at Evergreen. ALAS, 21 May 2005. Web. 19 Apr. 2010. <>.

Oberbauer, S. F., and B. R. Strain. 1986. Effects of canopy position and irradiance on the leaf physiology and morphology of Pentaclethra macroloba (Mimosaceae). American Journal of Botany 73:409-416.

Wright, S. J., and Carel P. Van Schaik. "LIGHT AND THE PHENOLOGY OF TROPICAL TREES." The American Naturalist 143.1 (1994): 192-99. JSTOR. Web. 18 Apr. 2010. <>.