Canangium odoratum (Lam.) Baill. ex King

An evergreen tree, 10-40 m tall, in cultivation often pruned to 3 m; trunk up to 75 cm in diameter, without buttresses; bark pale grey or silvery, smooth. Branches drooping, or slightly erect with dangling leafy twigs; young twigs minutely pubescent, glabrescent. Leaves alternate, distichous, simple, exstipulate; petiole slender, 1-2 cm long, narrowly grooved, glabrous; blade elliptical to ovate-oblong, 13-29 cm x 4-10 cm, base often oblique, rounded cordate, margin more or less undulating, apex acutely acuminate, membranous, midrib and lateral veins mostly whitish-pubescent on both sides, secondary veins in 8-9 pairs, clearly visible on both sides, often with small, hairy, pitted glands in vein axils. Inflorescence a raceme, 1-4 cm long, with 2-6 flowers on short, leafless, axillary shoots, dangling in clusters of 1-3 from the older branches behind the leaves; flowers 5-7.5 cm long, bisexual, green turning light dull yellow, overpoweringly fragrant when mature; pedicel 2-5 cm long; sepals 3, ovate, 5-7 mm x 5 mm, reflexed; petals 6, in 2 whorls of 3, linear-lanceolate, 3-9 cm x 5-16 mm, often curled or wavy, with purple brown spot at the base inside; stamens numerous, closely arranged, linear, 2-3 mm long, with a broad, cone-shaped appendix of the connective; staminodes absent; carpels many, with slender style and discoid stigma. Fruit pendulous, consisting of many (7-16) separate, globose-obovoid monocarps, about 2.5 cm x 1.5 cm on stalk 1-2 cm long; monocarp dark green, ripening blackish, 2-12-seeded, with seeds embedded in yellow oily pulp arranged in 2 rows. Seed flattened, ellipsoid, 9 mm x 6 mm x 2.5 mm, pale brown, surface pitted, hard, with a rudimentary aril. The habit of C. odorata is typically a straggling, pendulous tree: branches and leaves droop, long leafy sprays may dangle for a length of 3-6 m, flowers hang in loose bunches, and the petals are flaccid. Although the trunk continues to the top of the tree, it is commonly bent. A dwarf variety of C. odorata known as var. fruticosa (Craib) Sinclair, is often seen in tropical gardens. It is a bush 1-1.5 m tall, with frequently supernumerary, very curly petals. It flowers throughout the year, but never sets fruits. It probably originates from Thailand. Two groups can be distinguished in cultivated C. odorata: cv. group Cananga (forma macrophylla Steenis), flowers are the source of cananga oil; branches perpendicular to the stem; leaves 20 cm x 10 cm; cultivated in Java, Fiji and Samoa; and cv. group Ylang-ylang (forma genuina Steenis), the source of ylang-ylang oil; branches more drooping; leaves smaller; probably originating from the Philippines and cultivated throughout the tropics.

At sea-level, saplings of cultivated trees of C. odorata flower when 1.5-2 years old and 2 m tall; at 500 m altitude flowering may start only after 7 years. Wild trees do not flower until they are 9-12 m tall. When the buds open, the flowers are not yet fragrant and the petals are green and covered with white hairs; the petals enlarge, become glabrous and turn from green to yellow after 15-20 days and then the flowers emit their powerful and agreeable odour, discernable at a distance. Both cultivated and wild trees flower throughout the year, but with marked seasonal peaks after periods of dry weather. In Peninsular Malaysia there is regular flowering for several weeks between February and May and often a second flowering between August and October. In Java there are 3-4 peaks in flowering; flowering is most abundant at the end of the rainy season, while flowers are richer in oil during the dry season. The oily fruits are eaten by squirrels, bats, monkeys and birds, by which means the seed is dispersed.

It grows well on light, well-drained soils with pH 4.5-8, preferring rich volcanic or fertile sandy soils. Because of the long taproot, deep soils are required. Waterlogging for prolonged periods, but not permanent marshy conditions are tolerated; saline and alkaline soils should be avoided.

C. odorata thrives in the more humid lowland tropics with an annual rainfall of (650-)1500-2000(-4000) mm and an average annual temperature of 21-27 deg. C. In Java it grows gregariously in moist evergreen forest and in teak forest. In New Guinea it grows up to 850 m altitude. When planted it is found up to 1200 m.

Commercial cultivation of C. odorata for the production of ylang-ylang oil started in the Philippines, later followed by the production of cananga oil in Indonesia. The First World War almost destroyed ylang-ylang cultivation in the Philippines, only one plantation continuing cultivation until the Second World War. In the Philippines C. odorata is now a smallholder crop grown almost exclusively for local use. In 1770 C. odorata was brought from the Philippines to RÚunion, where commercial production of ylang-ylang oil started a century later. Production grew steadily, but declined sharply during the First World War; it never recovered and production virtually ceased during the economic depression of the 1930s. In the beginning of the 20th Century C. odorata was introduced into the Comoro Islands, where an important industry developed. Production peaked during the 1980s, but then declined due to the development of tourism and expansion of food production. Similarly, an ylang-ylang industry developed in the northern Madagascan island Nosy BÚ; it peaked around 1950 and then gradually declined. In Guangdong Province in southern China, production started recently and is still expanding. Indonesia, the Comoro Islands and Nosy BÚ are the main exporters of ylang-ylang oil. Java is the main producer of cananga oil; outside Java, the production of cananga oil is only important in Fiji.

Propagation of C. odorata is by seed or wildlings. Fresh seed germinates erratically; after 6-12 months storage the germination rate is higher. Hot water treatment of seed is used successfully in Nosy BÚ. Vegetative propagation by stem cuttings and budding have been tried with varying success. Plants may be raised in nursery beds, but should be handled with great care during transplanting to avoid damage to the long taproot. Direct sowing is common and seed is placed 5 cm deep in well-cultivated and fertilized planting pits of at least 50 cm depth.

Plantation: Plant spacing is at least 6 m x 6 m. A well managed plantation may remain productive for 50 years. Husbandry: Young plantations of C. odorata are often intercropped with food crops. Ring weeding and slashing of the inter-rows are important for optimal growth. For ylang-ylang production, trees are usually topped at about 3 m after 2-3 years. Topping promotes the growth of low, drooping branches, which are also tied down to pegs to keep the flowers within easy reach. In traditional production of cananga oil, often in home gardens, the trunk is left to grow. A well-managed plantation may remain productive for 50 years.

Very little is known about diseases and pests of C. odorata. Stem borers, flower-eating beetles and insects that cause the leaves to wilt have been reported.

Shade or shelter: In Malaysia, C. odorata is mainly planted as a roadside shade tree.

Essential oils: The fragrant flowers of C. odorata are used for personal adornment and decoration at festivities and other celebrations. Malaysians and Indonesians are very fond of the scent, and the women like to hide a flower in their hair. Fresh flowers of C. odorata mixed with flowers of Jasminum sambac (L.) Aiton, Rosa spp., Michelia champaca L. and leaves of Pandanus amaryllifolius Roxb. are used in various ceremonies in Java and Bali. The flowers are also put away with clothes, or scattered about the bed. The Thai apply an infusion of the flowers on the body after bathing. Two forms of C. odorata are grown commercially: cv. group Ylang-ylang, which produces ylang-ylang oil and cv. group Cananga yielding cananga oil. Both oils are distilled from the flowers, and are sometimes used in foods and beverages. Cananga oil mixed with coconut oil is used as a hair oil named Macassar oil (this oil differs from the seed oil from Schleichera oleosa (Lour.) Oken that is also called Macassar oil). Ylang-ylang oil and cananga oil are used to supply the dominant odour note of many perfumes. 'Extra' quality ylang-ylang oil is much used in high-class perfumery; 'Third' grade ylang-ylang oil and cananga oil have a harsher, more tenacious odour and are mainly used in soaps and toiletries for men. Medicine: C. odorata has several uses in traditional medicine. The dried flowers are used in Java against malaria and the fresh flowers are made into a paste for treating asthma. In Perak the leaves are rubbed on the skin against itch, and in West Java the bark is applied against scurf. The seed used to be used externally to cure intermittent fever. Timber: The timber is white to grey, non-durable and mainly used for boxes. It has potential for making small drums and matchsticks. Fibre: The bark can be beaten to make coarse ropes; this is done in Sulawesi.