Genus Aleurites in Family Euphorbiaceae

Genus Description

Aleurites is placed in the spurge family, Euphorbiaceae (APG IV, 2016; WFO, 2024). The genus comprises about two species and is distributed across Malesia, the western Pacific, and was introduced to parts of the Americas; the type commonly treated as Aleurites moluccanus (the candlenut) occurs naturally in lowland coastal and limestone forests from the Philippines to Polynesia (POWO, 2024; WFO, 2024). Aleurites fordii (syn. Vernicia fordii) is cultivated primarily in warm temperate Asia and is sometimes treated as a separate genus, Vernicia, as noted in recent revisions (Hu et al., 2019).

Distinguishing features include large, palmately lobed leaves that are glabrescent to persistently stellate-tomentose on the undersides; minute or caducous stipules; axillary, thyrsoid to paniculate inflorescences bearing unisexual, actinomorphic flowers with five sepals and five white petals; and a superior, usually three-locular ovary with a single ovule per locule inserted axially on a conspicuous placenta (Radcliffe-Smith, 2001; Ford et al., 2008). The fruit is a drupe or capsule-like with a fleshy to leathery exocarp, and the seeds are large and oily; indumentum when present is typically dendritic to stellate, which helps separate Aleurites from related genera lacking such hairs (Radcliffe-Smith, 2001).

The center of diversity lies in Malesia and the wider Pacific, with Aleurites moluccanus showing widespread island distribution and pronounced endemism patterns on Pacific islands and limestone habitats; Aleurites fordii is cultivated in warm temperate regions of southern China and northern Vietnam. Species typically inhabit coastal forests, secondary growth, and karst outcrops at low elevations, although Aleurites fordii extends into higher altitudes within its cultivation range (POWO, 2024; WFO, 2024).

Pollination is by insects and the fruit is dispersed by birds or water, consistent with its oceanic island ecology (Ford et al., 2008). Life history includes rapid early growth and a tendency toward re-sprouting after damage. Chromosome numbers for Aleurites are documented as 2n=44 in Aleurites moluccanus (Kong et al., 2002), but a stable base number for the genus is not firmly established.

Taxonomically, some authors segregate Aleurites fordii into Vernicia (Hu et al., 2019), while Aleurites moluccanus has sometimes been transferred to Reutealis as R. trisperma, although such moves are not universally followed (POWO, 2024; WFO, 2024). Ongoing plastid and nuclear data continue to refine relationships within Euphorbioideae, supporting careful circumscription and the potential for further fine-scale adjustments in Aleurites and allied genera (Wurdack & Davis, 2009; APG IV, 2016).

The genus is best known as the source of tung oil from Aleurites fordii, a quick-drying oil widely used in wood finishes and industrial applications; Aleurites moluccanus provides edible oil and is an ornamental street tree in tropical regions (Ford et al., 2008). Both taxa can become weedy when cultivated outside their native ranges.

Conservation concerns are largely focused on habitat loss and hybridization risks between cultivated and wild populations, particularly for Aleurites moluccanus on small islands (WFO, 2024). Better integration of phylogenetic frameworks with population-level data will improve conservation assessments and management priorities across the genus (APG IV, 2016; Ford et al., 2008).

• Aleurites moluccanus (Willd.)
• Aleurites rockinghamensis ((Baill.) P.I.Forst.)