In 1811, Robert Brown, a British botanist, established a new genus, namely, Hoya, in the family Apocynaceae. This tropical climbing plant was dedicated to Thomas Hoy, a gardener at Syon House, England, and consists of 200 to 230 species. In Peninsular Malaysia, 28 Hoya species have been recorded (Lamb & Rodda, 2016).
Hoya elliptica was first described by Sir Joseph Dalton Hooker in 1883 and it is named after its characteristic elliptic leaves. This is one of the few species that produces laterally held inflorescences, which is also seen in H. mitrata and H. ruthiae.
Hoya elliptica is a medium-sized epiphytic climber that is always found on tree trunks. The petioles are round to slightly grooved. It has evergreen foliage; the leaves are thick and leathery, elliptic with a fleshy lamina and apparent lighter green pinnate venation (Flora Fauna Web, 2018). Species of Hoya produce sap which can be of different colours. For example, some species like H. caudata produce a yellow sap while others like H. obtusifolia have blue sap. Hoya elliptica has a white sap that is mildly poisonous and which can irritate sensitive skin.
The inflorescences are negatively geotropic or held laterally, convex to almost globose and bear 10 to 35 flowers borne on a glabrous slender peduncle. The peduncle is around 0.5 to 5.0 cm long. The flowers are erect, 9 to 12 mm in diameter. The white corolla is one of its characteristics. The corolla lobes are reflexed and pubescent inside but glabrous towards the apex. The corona lobes are oblong, laterally compressed and white in colour. The centre of the corona is purple with bright yellow anthers. The fruits are fusiform, broadest at the middle and tapering towards the tip, about 10 to 15 cm long.
Hoya elliptica is widely distributed in Sumatra, Peninsular Malaysia, and Borneo (Kalimantan and Sabah) (Lamb & Rodda, 2016). Based on collections in the Kepong Herbarium, H. elliptica has been recorded from the river edges of Sungai Batu and Sungai Langat (Selangor), Stong Tengah F.R. (Kelantan), and Kledang Saiong F.R. (Perak). It is often found from sea level up to 500 m altitude, usually on trees growing along rivers and streams.
Since H. elliptica has attractive and scented flowers, and is easy to propagate from stem or root cuttings, it is popularly planted as an ornamental plant in small gardens, hanging baskets, and containers (Flora Fauna Web, 2018). Its conservation status has not been evaluated in the IUCN Red List due to lack of data. Presently it is also not possible to assess their local vulnerability due to lack of adequate distribution data.
