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Hoya australis R. Br. ex J.Traill 1828
pronounced: HOY-uh oss-TRAH-liss
(Apocynacae – the oleander family )
common name: Waxflower
Hoya was named by the botanist Robert Brown after Thomas Hoy, gardener to the Duke of Northumberland at the end of the 18th century. Brown (1773–1858) was the botanist to Matthew Flinders in his voyage on Investigator, and became a leading figure in 18th century botanical circles. Australis is Latin for south.
This plant is found as an epiphyte, usually growing high up on the trees in rainforests and rainforest margins in eastern and northern Australia, from Western Australia through the Northern Territory and down coastal Queensland from Cape York to northern NSW. Like all the Hoyas, it is a climbing plant with adventitious roots and with succulent foliage. It is the most widespread and the most commonly grown of the Australian species.
The stems and leaves contain a white milky sap.
The leaves are glossy, elliptical to ovate in shape and about 2.5-8 cm by 2-4.5 cm, on petioles 1-2 cm long. Colleters are present on the upper surface of the midrib near its junction with the petiole. Both surfaces of the leaf blades are covered in hairs. Leaves that grow in sunnier positions are a more yellowish green, while those that grow in the shade are dark green in colour.
Each flower is 1.5-2.5 cm in diameter, with 5 thick waxy triangular petals, white in colour with deep red markings in the centre. They produce an abundant quantity of nectar. The flowers are borne on the same stalk in successive seasons, and this stalk should not be removed after flowering, or no more flowers will develop.
The slender seed pods are about 10 cm long, and contain numerous seeds, each about 3-4 mm long. Plumes 15-25 mm long are attached to one end of the seed.
The plant can be grown from fresh seed, and cuttings also strike readily. The plant is easily cultivated in tropical and subtropical areas, and will even succeed in temperate areas if protected from frost (it will tolerate light frosts). It is well suited to growing in containers and hanging baskets, being quite tolerant of root restraint. It will grow in quite deep shade, but flowers best in good light.
This is a food plant for the caterpillars of Euploea alcathoe (the no-brand crow) and E. core (the common crow) butterflies. The flowers are pollinated by Ocybadistes walkeri (the southern grass-dart).
Hoya australis may cause problems with cattle in times of drought, if they eat too much of it. It can damage their spinal cord, leading to collapse and death.
Photographed on Magnetic Island 2017
Page last updated 19th March 2018