Cananga odorata, commonly known as Ylang-ylang in English, belongs to the Annonaceae or custard-apple family, and is well-known for its fragrant flowers. In Malay, it is known as Kenanga or Kenanga hutan. Presently, the genus Cananga consists of two species, namely, Cananga odorata and Cananga brandisiana (Plants of the World Online: Kew Science). The genus name Cananga is derived from the Malay vernacular name ‘Kenanga’ (Turner & Veldkamp, 2009), whereas the species name odorata is derived from the Latin word, which means fragrant or sweet-scented.
The flower of C. odorata has three sepals and six petals up to 8 cm long. The petals are twisted when young, turning limp and drooping when mature. There is a dwarf form of C. odorata called C. odorata var. fruticosa which grows to only 1.5 m in height. This plant with very curly-petaled flowers is often seen in tropical gardens. It flowers all year round but never produces fruits (Manner & Elevitch, 2006). Within the custard-apple family the common name Ylang-ylang also refers to Artabotrys hexapetalus, an evergreen climbing shrub from India. The flower of this plant is also fragrant and greenish-yellow to yellowish-brown in colour when mature, which is similar to C. odorata. However, its flowers are unattractive and smaller in size, with six non-twisted petals.
Generally, C. odorata is a medium-sized evergreen tree that grows up to 30 m in height and has a fast growth rate of more than 2 m per year in its early years. It has long drooping, leafy twigs dangling 3-6 m and the bark is greyish white to silvery and smooth. The leaves are dark shiny green, simple, alternate, and ovate-oblong shaped (Adnan et al., 2018). The flowers are pollinated by nocturnal moths and relatively small beetles from the families Curculionieae, Nitidulidaea, and Chrysomelidae. The distinctive aggregate fruits are greenish-black, olive like, 8−15 individually stalked, and turn from dark green to black when ripened. Small mammals such as monkeys, bats, squirrels, and frugivorous birds are known to eat the fruits and disperse the small hard seeds (Parrotta, 2014). The seeds are pale brown, flattened, ellipsoid, smooth, and irregularly pitted.
Commercially, essential oils extracted from the flowers of C. odorata are used in beauty products such as perfumes, soaps, shampoos, and hair oils (Parotta, 2014). The essential oils from the tree have also been reported to be one of the ingredients used in natural insect repellent products as has been demonstrated in studies against several mosquito species (Tan et al., 2015). In Malaysia, the tree is used as an ornamental plant in streets, parks, or large gardens as its very pleasant fragrance makes it appropriate in landscaping. In Borneo, the dried flowers of C. odorata are worn in women's hair and also placed between clothes due to its fragrant scent (Parotta, 2014).
Cananga odorata is widely distributed from Australia, India, Indonesia, Malaysia, Papua New Guinea, Philippines, to the Solomon Islands (IUCN, 2019). In Malaysia, it generally grows wild on forest edges in the northern region of Peninsular Malaysia to Negeri Sembilan (Ong, 2004). This species is frequently found in Sabah but is much rarer in Sarawak. It inhabits lowland forest, both primary and secondary up to 200 m altitude (Turner et al., 2014). Ylang-ylang is a light-demanding species; it needs a hot and wet climate, well-drained fertile sandy loam soils, preferably a rich volcanic soil, and protection from strong winds (Manner & Elevitch, 2006).
Globally, C. odorata is considered as Least Concern by the IUCN Red List (2019) as it currently faces no significant or major threats. In the Malaysia Plant Red List Book it is listed as Not Evaluated for Malaysia (Chua et al., 2010).