Aleurites is a small genus of large evergreen trees in the spurge family Euphorbiaceae, order Malpighiales, first described as a genus in 1776. The genus is native to China, the Indian subcontinent, Southeast Asia, Papuasia, and Queensland, and has become naturalized across Pacific and Indian Ocean islands, the Caribbean, parts of Africa, South America, and Florida.
These monoecious trees reach 15–40 metres in height with spreading, drooping, and rising branches. The leaves are alternate, lobate, and ovate to ovate-lanceolate, pubescent when young and becoming glabrous with age. The inflorescence forms terminal plumes of small, creamy white, bell-shaped, fragrant flowers; pistillate flowers occupy the end of each major axis while lateral cymes are staminate. Fruits are large drupes with a fleshy exocarp and a thin woody endocarp, containing oleiferous seeds that are toxic in their raw state.
The genus is best known for the candlenut (Aleurites moluccanus), the most widespread species and the sole member present across most of the genus range, from India and China through Polynesia to Australia. The seeds yield an oil that has historically served as paraffin, lubricant, and a constituent of varnish, paint, and soap; once toxins are removed the oil is also used in cooking. Some formerly included deciduous Chinese species have been reclassified to the related genus Vernicia, and other former members have been moved to Croton, Mallotus, Omphalea, and Reutealis.
Etymology
The genus name Aleurites is derived from the Ancient Greek ἄλευρον (aleuron), meaning "wheaten flour" or "ground meal", an allusion to the pale, mealy appearance of the lower surface of the leaves. The genus name was originally treated as feminine by Linnaeus, but under the current International Code of Nomenclature for algae, fungi, and plants, all genus names ending in -ites take the masculine gender, making the correct species epithet moluccanus rather than moluccana.
Distribution
Aleurites is native to China, the Indian subcontinent, Southeast Asia, Papuasia (New Guinea and adjacent islands), and Queensland in northeastern Australia. It has been widely naturalized beyond its native range, with established populations on islands of the Pacific and Indian Oceans, in the Caribbean, and at scattered locations in Africa, South America, and Florida.
Cultural Uses
The seeds of Aleurites moluccanus (candlenut) contain an oil that has been put to many uses across the genus's range. Historically the oil served as a paraffin substitute, lubricant, and ingredient in varnish, paint, and soap manufacture. When the toxic compounds are rendered harmless, the oil is also used as a cooking oil. The candlenut is the state tree of Hawaii and has deep cultural significance across Polynesia and Southeast Asia.
Taxonomy Notes
Aleurites was first described as a genus in 1776. Several deciduous Chinese species formerly placed here — including the tung trees — are now classified in the separate genus Vernicia. Other former members have been reassigned to Croton, Mallotus, Omphalea, and Reutealis. In its current circumscription, some botanists recognize only two species: A. moluccanus and A. rockinghamensis.
