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Hoya carnosa (L. f.) R.Br. 1810
pronounced: HOY-uh kar-NO-suh
(Apocynaceae – the oleander family)
common name: Wax Plant
Hoya carnosa is one of the hundred or so species of Hoya that are native to eastern Asia and Australia. Hoya was named by the botanist Robert Brown after Thomas Hoym, 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 the leading figure in 18th century botanical circles. Carnosa comes from the Latin carnosus, fleshy.
This attractive waxy-leaved vine bears clusters of star-shaped pink-white blossoms in summer. The delicate flowers look as if they are made of porcelain, and Hoya carnosa makes a good house plant. Those seeing Hoya blossoms for the first time may need to touch them to make sure they are not artificial. The specimen photographed is trained on a small tree.
Hoya vines will grow up to 10 metres or more with suitable support in trees. They have simple opposite leaves anywhere from 5 cm to 30 cm in length that are typically succulent, while the leaves of some species are flecked with irregular small silvery spots. The flowers appear in axillary umbellate clusters at the apex of peduncles with repeated clusters of flowers developing in sequence on each peduncle. Each flower is pink-white, about 1 cm in diameter, with five thick, waxy petals. The flowers are sweetly scented, and produce plenty of nectar. The pods are long and cylindrical, and twist open on ripening to release the seeds, which have a fluffy end, and are dispersed by the wind.
New growth appears first as leafless extensions up to 2 m long. Once they are at their full length, new portions of the vine produce pairs of leaves along the stem. Such a growth habit allows Hoyas growing in the wild to extend their new growth long distances through the branches of trees before they become weighed down by leaves.
The plant may be started from seed, or from stem cuttings. A portion of stem including one or more pairs of leaves will quickly produce roots in water or damp sand. Plants do not usually flower until they are four years old. Since flower clusters are produced on the same stems yearly, best results in the following year will be obtained if the flowering spurs are left in place when the flowering is over.
When Hoya carnosa is grown as a house plant, many people find that the scent it releases in the evening is rather overpowering – the scent from a single plant can fill a whole house. Some people place the plant outside at night for this reason.
As is typical for the members of the oleander family (sometimes called the dogbane or milkweed family), Hoya exudes a sticky sap if cut or damaged.
Photographs taken in Picnic Bay 2008, 2010
Page last updated 12th December 2016