Croton moluccanus L.

Aleurites moluccana is a medium-sized tree, up to 20 m tall, with wide-spreading or pendulous branches. Bark grey-brown, fairly smooth with fine vertical lines. Leaves simple, variable in shape, young leaves large, up to 30 cm long, palmate, with 3-7 acuminate lobes, shining; whitish above when young, becoming green with age, with rusty stellate pubescence beneath when young that persists on veins and petiole; leaves on mature trees ovate, entire, acuminate, long-petioled. Flowers in rusty-pubescent panicled cymes, 10-15 cm long; petals 5, dingy white or creamy, oblong, up to 1.3 cm long; ovary 2-celled. Fruit an indehiscent drupe, almost spherical, 5 cm or more in diameter, with thick, rough, hard shell making up 64-68% of fruit; difficult to separate from kernels; containing 1-2 hard-shelled black seeds. The generic name ‘Aleurites’ comes from a Greek word ‘aleuron’, meaning ‘floury’. The Hawaiians strung nuts on sticks and used them for lighting houses; this use of the kernels gave rise to the name ‘candle nut’.

In Sri Lanka, the flowering period is from April to May. In Uganda, flowering may be several times each year. Pollen vectors are honeybees and other hymenopteran species. Major dispersal agents of the fruits are birds.

A pH of 5-8 is ideal for growth.

The striking A. moluccana is found on hillside forests of the Pacific and Southeast Asia, where its pale, mealy foliage stands out from darker tropical vegetation. The tree thrives in moist tropical regions, ranging from subtropical dry to wet through tropical very dry to wet forest life zones.

A. moluccana is one of the great domesticated trees of the world with multiple uses; it has been adopted as the official tree emblem of Hawaii, where it was probably imported by Polynesian ancestors.

Seed production is profuse and seeds are easily collected. Seedlings are derived from wildings, direct sowing and pot-sowing. It grows easily from seed and in Uganda has become invasive in the wetter parts of the country. Difficulty has been experienced in germinating the seeds of A. moluccana. The seeds are very hard-shelled, and untreated seeds have been known to stay in a seedbed for as long as 38-150 days before germination. The most satisfactory method of treatment is to place a single layer of seeds on the ground and cover them with dried leaves or grass. The grass is then burned. Immediately after burning and while seeds are still hot, they are thrown into cold water, which results in the cracking of the hard shells. The results of this kind of treatment showed an average germination of more than 30%. For even faster germination, the seed can be cracked. Kernels adhere to sides of the shell and are difficult to separate. A. moluccana tree can also be grown from cuttings.

Seedlings are planted at a density of 300/ha. Once established, trees require little to no attention. Bears 2 heavy crops each year; harvested when mature. In plantations nut yields are estimated at 5-20 t/ha nuts, each tree producing 30-80 kg. Oil production varies from 15 to 20% of nut weight. Most oil produced in India, Sri Lanka and other tropical regions is used locally and does not feature in international trade. Coppices when young and responds to pollarding when old.

The following fungi are known to attack A. moluccana: Cephalosporium spp, Clitocybe tabescens, Fomes hawaiensis, Gloeosporium aleuriticum, Physalospora rhodina, Polyporus gilvus, Pythium ultimum, Sclerotium rolfsii, Sphaeronema reinkingii, Trametes corrugata, Ustulina deusta and Xylaria curta. Nematodes include Meloidogyne spp.

Seed storage behaviour is orthodox, 79% germination following 79 years of storage. There are about 345 seeds/kg.

Shade or shelter: The leafy rounded crown provides shade. Soil improver: Seed press cake is suitable as a fertilizer. Ornamental: A. moluccana is an attractive tree with its cream white flowers that may appear more than once a year.

Food: Kernels when roasted and cooked are considered edible; may be strung as candle nuts. After removing the hard outer coat, the seed is pounded and eaten as a sauce. Per 100 g, the seed is reported to contain 626 calories, 63 g fat, 19 g protein, 8 g total carbohydrate, 7 g water, 3 g ash, 200 mg phosphorus, 80 mg calcium, 2 mg iron, and 0.06 mg thiamine. Fuel: Seed oil is suitable, with modification, for use as a substitute for diesel, the residues for conversion to alcohol or pyrolysis. In Uganda, it is planted as a backyard tree for firewood. Timber: Wood whitish and soft and suitable as a timber species. Tannin or dyestuff: Bark contains about 4–6% tannin. Lipids: Seed yields 57-80% of inedible, semi-drying oil, liquid at ordinary temperatures, solidifying at -15 deg. C, containing oleostearic acid. The oil, quicker drying than linseed oil, is used as a wood preservative, for varnishes and paint oils, as an illuminant, for soap making, waterproofing paper, rubber substitutes and insulating material. Oil is painted on bottoms of small crafts to protect against marine borers; also prevents feeding by striped cucumber beetle. The oil is inferior to tung oil, extracted from a related Chinese species, A. fordii, and used mainly for varnishing wood. Commercial production of oil yields 12-18% of the weight of the dry, unhulled fruits, the fruits being air-dried to about 12-15% mc before pressing. Oil yields as high as 300 kg/ha have been reported. Poison: Seeds are moderately poisonous. The oil cake, containing about 46% protein, is said to be poisonous. Medicine: Bark used to treat tumours in Japan. The oil is purgative and sometimes used like castor oil. Kernels are laxative, a stimulant and a sudorific. The irritant oil is rubbed on scalp as a hair stimulant. In Malaya, the pulped kernel is used in poultices for headache, fevers, ulcers and swollen joints. In Java, the bark is used for bloody diarrhoea or dysentery. Bark juice with coconut milk is used for sprue. Malayans apply boiled leaves to the body for headaches and gonorrhoea.