Vatica odorata, a member of the Dipterocarpaceae, is known by the locals in Peninsular Malaysia and Sarawak as Resak ranting kesat. The vernacular name is derived from its characteristic twigs (Symington et al., 2004). In Malay, Resak is the name of the genus Vatica, while ranting means twig and kesat is an adjective meaning rough. The roughness is caused by the presence of a tomentum of soft rusty coloured hairs on the surface of the twigs. The term “pubescent” can also be used to refer to this characteristic. In Sabah, this species is known as Resak biabas. Biabas is a Borneon indigenous peoples’ word which refers to Guava fruit trees (Schneeberger, 1937) or Psidium spp. The characteristic twigs and leaves of V. odorata resemble the greenish brown pubescence of the Guava twigs and leaves.
Generally, V. odorata is a small-sized tree and has a slow growth rate. However, it is still known to grow up to 40 m tall and 60 cm dbh. The leaves are thinly coriaceous and the leaf blade is narrowly elliptic to ovate with 11—15 lateral veins. Other than the twigs, the calyx of the flowers and the calyx lobes of the fruits are also densely pubescent. The flower petals are pale yellow and about 6-10 mm long. The term odorata in its Latin name means scented and is in reference to the pleasant smell of its flowers. The fruit is a globose nut, with 2 wings of about 5.5 X 1.5 cm and 3 shorter calyx lobes of about 14 mm length (Ashton et al., 2004; Symington et. al, 2004).
This species can be found in South China, Myanmar, Thailand, Indo-China, Peninsular Malaysia, Borneo and the Philippines. It is widely distributed in Malaysia and is divided into two subspecies, namely, V. odorata subsp. odorata and subsp. mindanensis (El-taguri et al., 2020; Julia et al., 2016; Chua et al., 2010; Ashton et al., 2004; Symington et al., 2004). The former subspecies is widespread in Peninsular Malaysia but rare in Sabah and Sarawak. It inhabits lowland and hill forests up to 700 m altitude (Ashton et al., 2004). The second subspecies is widely distributed in Sarawak and can also be found in Sabah but has not been recorded from Peninsular Malaysia. It is recorded to inhabit lowland to upper montane and kerangas forest up to 1,100 m altitude (Julia et al., 2016).
The timber of Vatica spp. and another dipterocarp, Cotylelobium spp., is commonly known as resak in Malay. Resak is well known as a valuable medium to heavy hardwood. The timber is used in heavy construction, piling, ship flooring, furniture production, and for many other purposes (Malaysian Timber Council, n.d.; Lemmens, 1993).
The conservation status of V. odorata subsp. odorata in the IUCN Red List is Least Concern (LC) while for V. odorata subsp. mindanensis is Endangered (EN) (Ashton, 1998). However, according to Chua and co-workers (2010) V. odorata ssp. odorata is categorised as Vulnerable (VU) for Malaysia. The Sarawak Plant Red List lists V. odorata ssp. mindanensis as Least Concern (LC) as this subspecies is widely distributed and occurs in both Totally Protected Areas and protection forest (Julia et al., 2016). Thus, the current global conservation status for both subspecies is in need of updating.
A living collection of Vatica odorata ssp. odorata can be observed at the Dipterocarp Arboretum of the Forest Research Institute Malaysia at Kepong, Selangor. The tree at the arboretum has many low branches, hence, its characteristic rough and hairy, rusty-coloured twigs can be observed easily under the canopy. This tree was last recorded fruiting in April 2017. The exact fruiting and flowering pattern of V. odorata is unknown. Various factors such as temperature, humidity and solar radiation could determine the flowering and fruiting frequency of a species. Based on my observations in FRIM since 2016, some Vatica spp. such as V. bella, V. paucfilora and V. umbonata flower and fruit annually and sometimes even twice a year, as recorded by Suhaida et al. (2018) for V. yeechongii in Sg. Lalang Forest Reserve. Long-term monitoring and further studies are needed in order to further understand the reproductive behaviour of V. odorata and other Vatica spp.