It has hard timber which is not very resistant to rot in the tropics, but it can be treated, has a pretty pink-red colour when dry, and has a number of uses.

Despite their toxicity, the seeds are eaten by variegated squirrels, parrots and macaws, and serve as the nurseries of the larvae of the moth Carmenta surinamensis.

In Costa Rica it grows to the greatest dimensions and is usually a canopy tree which reaches a trunk diameter of 130 centimetres (51 in),[3] and heights of 30–40 metres (98–131 ft).

There are 30 to 50 pairs of second-order leaflets which are leathery in texture,[8] narrowly falcate, with a pilose to glabrescent indumentum, and multiple linear ribs.

[9] The greenish-brown calyx is gamosepalous with the sepals being imbricate (having overlapping edges), and about 2 cm long with a joint base and five free lacinia (narrowly-incised segments between them).

[3][5] A Brazilian study found the petals are uniformly dark red at the base and yellow at the apex in their specimens.

Their anthers carry a conspicuous apical gland and five long (2.5 cm), white staminodes, which have filaments with a small appendage at their terminal ends.

[5] The apical gland mentioned above is a rather unique and mysterious anatomical feature found only in the anthers of mimosids and related legumes.

[9] The shape is falcate or linear-spatulate and flattened, with the greatest width above the middle, the base being attenuated truncate and the apex being rounded.

[6] When the seeds germinate, thick and large, green-coloured cotyledons open at the soil surface, and send up a shoot, called the epicotyl.

The epicotyl is slightly twisted, it first grows cataphylls that wither and are shed early in the development, and then bears a first pair of alternate eophylls, before developing bipinnate leaves, with leaflets that have waxes and simple trichomes on their upper surface at the margins, and stomata on the bottom surface.

[6] The plant can be recognised as belonging to this species by: not having any spines, bipinnate leaves without nectar glands, inflorescences as large spikes covered in conspicuous white stingy staminodes, and fruit held above the branches, in the shape of a machete, which open with an elastically explosive mechanism from the apex to the base.

[6] According to one 1983 source, it exists in three disjunct populations, one through the lowlands of northeast Venezuela through the Guianas, including Trinidad and Tobago.

[9] In eastern Panama it is the dominant tree in certain moist, seasonal, swamp forests in coastal areas of the Atlantic.

[23] In La Selva Biological Station Pentaclethra macroloba constitutes 40% of the basal area and up to 18% of the stem density in parts of the forest, where it forms monocultural stands.

[21] In 2001 the discovery was published that submerged seeds develop air pockets that allow them to float; this was then interpreted as evidence that the species has adaptions for dispersal by water (hydrochory).

This is believed to be due to the action of the floodwaters during high tide, the floating seeds end up stuck behind fallen branches, buttress roots or other objects, often in great numbers.

[22][23] Like many leguminous plants, P. macroloba is a nitrogen fixer which forms a symbiotic relationship with Rhizobium, which grows in specialised root nodules.

[27] Gary Hartshorn, a forester at the US World Forestry Center at the time, wrote an account on the species in the 1983 book Costa Rican Natural History, in which he principally theorised as to how the species had become so dominant in the monocultural forests of La Selva Biological Station.

Hartshorn noted the presence of the larvae of a wasp-like, clear-winged moth feeding in the seeds, but noted that their presence did not impede germination, and speculated that the opening of the cotyledons at the surface of the soil was perhaps a defensive tactic of the plant, as it exposes the caterpillars to foraging ground insectivores.

[10] The seeds are actually heavily predated upon, frequently ten or eleven insect larvae emerge through small holes on the exposed surface of the opened cotyledons.

[3] This appears to be primarily caused by the moth Carmenta surinamensis, which was found in 43.6% of the seeds in one study in Costa Rica.

[13] Hartshorn himself had noted in his earlier thesis paper that grey squirrels (Sciurus variegatoides) and white-crowned parrots (Pionus senilis) feed upon the seeds up in the trees while still in the unopened pods.

An explanation for this may be that the preferences of the squirrels and parrots are precisely diametrically opposed and they might cancel each other out, but it is also possible that the optimal foraging theory, which would have it that predators select the biggest and easiest to forage seeds, may not apply here, as both animals may be able to tolerate some toxins, they are still susceptible to them, and must limit their intake.

[29] In Mazagão, Brazil, it is found growing together with a high frequency of palms and the trees Carapa guianensis, Virola surinamensis, Mora paraensis, Calycophyllum spruceanum, Hevea brasiliensis, Platymiscium ulei, a Licania species, Cedrela odorata, Pterocarpus amazonicus, Symphonia globulifera, Licaria mahuba, Hernandia guianensis and others.

In Nigeria the seed of the related African species P. macrophylla is boiled and fermented with Bacillus subtilis, which detoxifies it of paucine.

[8] Traditional medicinal properties ascribed to this plant species by caboclos (Brazilian Portuguese for 'locals') and various native groups are as an antivenom against snakebites,[7][29][35] and as a curative for ulcers and insect bites.

[7] When Brazilian scientists tested an extract from the dried bark to see if any antivenom effect could be detected, it showed a measurable ability to reduce haemorrhaging in vivo when mixed with the venom and injected into mice.

Because electrophoresis showed that the snake venoms were not being degraded by the extract, which eliminated proteolytic enzymatic activity as the mechanism of action, the Brazilian scientists hypothesised that the effect was caused by an unknown substance with some kind of inhibitory action caused by the binding of the zinc ions required by snake venom metalloproteases to function.

[7] Two years later many of the same researchers had a new article published; this time they had isolated the compounds causing the protective effect, two triterpenoid saponins which they named macrolobin-A and B.