Culture
Winter hardy to USDA Zones 10-12 where best growth occurs in slightly acidic, medium moisture, well-drained loams in full sun. Tolerates some light shade. Best in climates with long humid summers. Thrives in deep fertile soils, but tolerates poor ones. Survives winter temperatures that dip to about
28 degrees F.
Noteworthy Characteristics
Aleurites moluccanus, commonly known as Kukui or candlenut tree, is a tropical broadleaf evergreen tree in the spurge family that is noted for producing attractive flowers, walnut-sized fruits and maple-like, pale green, evergreen leaves. It typically grows to 20-50’ tall, but less frequently to as much as 90’ tall. It is native from Indonesia and Malaysia into the western parts of Polynesia (exact native range is unclear), but very early spread and naturalized throughout Southeast Asia and the islands in the South Pacific. Polynesian settlers reportedly brought this tree to Hawaii where it has naturalized in open forests, lower alpine slopes, river margins, hillsides and ridges. Although not native to Hawaii, Kukui was designated the Hawaiian State tree in 1959. The flower has been designated as the island flower of Molokai. Historically, Hawaiians once strung candlenuts on a palm leaf tendril and burned them one at a time for light. They also extracted oil from the nuts for use as a fuel in stone oil lamps called Kukui hele po. Kukui means light, hence its use as a common name.
Spreading to downward-arching branches and twigs of this tree are clad with glossy, heart-shaped, triangular to oblong, pale green leaves (to 4-8” long) with toothed margins. Leaves often have 3-5 shallow lobes. Young leaves, young branches and inflorescences are stellate hairy. From a distance, this tree appears to have a white flour-like dusting.
Small-but-showy, 5-petaled, creamy white flowers bloom in dense panicled cymes (to 4-9” long) at the branch ends. Flowers are monoecious. Flowers typically bloom April to October, but may bloom irregularly throughout the year with flowers and fruits often being present on the tree at the same time in various stages of development. Female flowers are followed by thick-rinded, walnut-sized fruits (to 2” diameter), each containing 1-2 large, nut-like seeds (candlenuts) which have a high oil content. Nuts are pressed for oil which is not only used in candles/lamps, but is also used in making additional products such as soaps and varnishes.
Genus name comes from the Greek word aleuron meaning floury in reference to the white flour-like dusting present on juvenile leaves.
Specific epithet means from the Moluccas (aka Spice Islands) located in eastern Indonesia which is part of the native habitat for this tree.
Problems
No serious insect or disease problems. Susceptible to dieback and canker. All parts of this tree are toxic to humans if ingested, and in particular the seeds.
Uses
Where winter hardy, this evergreen tree has excellent ornamental features. Good landscape specimen or shade tree.