Gavilan / Oil Tree

Overview

Pentaclethra macroloba — known in Costa Rica as gavilan or gavilán (and as “oil tree” in English, for the oil-rich seeds once rendered commercially) — is the single most structurally important tree in the Caribbean lowland wet forests of Costa Rica. It is a large legume in the subfamily Mimosoideae, reaching 30–35 m at maturity, with a spreading crown, compound bipinnate leaves, and distinctive spike-like inflorescences. The seed pods are enormous — flat, woody, and up to 50 cm long — and explosive at maturity: the pods split with an audible crack and fling seeds several meters from the parent tree.

The species fixes atmospheric nitrogen through root nodule symbiosis, a trait that gives it a competitive advantage in the nutrient-poor, waterlogged soils of the Caribbean lowlands. This nitrogen input materially enriches the forest floor and makes P. macroloba a keystone ecosystem-engineering species as much as a dominant timber tree.

Why Tortuguero

This is the tree of Tortuguero. In forest-inventory plots within the park and at La Selva Biological Station (the closest intensively studied lowland Caribbean site), P. macroloba consistently forms 30–40% of stand basal area — a level of dominance unusual even by tropical-forest standards, where most species are rare and many canopy trees occur at densities of a few per hectare. The Tortuguero landscape is essentially a Pentaclethra forest with other species in the matrix.

Its tolerance of seasonal flooding (the park’s low-lying terrain floods annually with Caribbean rain events) explains both its dominance and its distribution: it occupies sites that exclude most competitors.

How to see them (honestly)

You cannot miss them. Pentaclethra macroloba is the canopy tree above every canal-side trail in Tortuguero. Identifiers:

• The large, flat, dark woody pods on the ground — look for the split valves that have already flung their seeds
• Bipinnate leaves (feathery, fern-like compound leaves with many small leaflets) typical of the legume family
• Pale bark with irregular shallow furrows, becoming rougher on older individuals
• Spike inflorescences in season — cream-colored, dense, and visible in the upper canopy

Any guided trail walk will include a close look at gavilan whether the guide flags it or not.

Status note

Globally Least Concern. Pentaclethra macroloba is abundant throughout its range and under no immediate threat of extinction. Within Costa Rica, timber extraction outside protected areas has reduced it in some accessible lowland sites, but within Tortuguero National Park it is untouched and structurally dominant. It is not a conservation concern; it is the reference ecosystem — the ecological baseline against which any lowland Caribbean forest degradation is measured.