Hoya australis explained

Hoya australis, commonly known as waxflower or common hoya,^[1] is a species of flowering plant in the Apocynaceae or dogbane family and is native to northern and eastern Australia, Papuasia and Melanesia. It is a succulent vine or subshrub with fleshy or leathery, elliptic, oblong, egg-shaped or more or less round leaves, racemes of fleshy, cream-coloured and red flowers, and spindle-shaped follicles. It is a popular garden plant, noted for its fragrant flowers.

Description

Hoya australis is a succulent climbing vine to subshrub that typically reaches a height of . It has fleshy or leathery, elliptic, oblong, egg-shaped or more or less round leaves up to long and wide. Leaves growing in sunnier positions are a more yellowish green while those in shadier situations are dark green in colour. The flowers are arranged in racemes in diameter, each flower long on a pedicel long. The flowers are fleshy, bell-shaped to wheel-shaped, cream-coloured with red under the corona, with egg-shaped lobes, long and wide. The flowers have a strong sweet scent and produce abundant nectar. The corona lobes are oval, cream-coloured, long and wide. Flowering time depends on subspecies, and the fruit is a spindle-shaped follicle long.^[2]

Taxonomy

Hoya australis was first formally described in 1828 by James Traill from an unpublished description by Robert Brown.^{[3] [4]} The specific epithet (australis) is Latin for "southern".^[5]

Subspecies

In 1988, Ken Hill described subspecies australis and subsp. sanae in the journal Telopea,^[6] and in 1991, Paul Irwin Forster and David Liddle described subsp. oramicola, subsp. rupicola and subsp. tenuipes, in the journal Austrobaileya,^[7] and the names are accepted by the Australian Plant Census:

• Hoya australis R.Br. ex J.Traill subsp. australis^[8] is a twining plant has leaves that are fleshy or succulent, sparse or densely hairy and not curved under, and has extrafloral nectaries. It flowers from March to July.
• Hoya australis P.I.Forst. & Liddle subsp. oramicola^[9] has leaves more than long, with obscure veins and the edges strongly rolled under. It flowers in July.
• Hoya australis (K.D.Hill) P.I.Forst. & Liddle subsp. rupicola^[10] is similar to subsp. australis, but is an erect plant that does not twine, has leaves that are succulent and not curved under, and lacks extrafloral nectaries. It flowers from January to March.
• Hoya australis subsp. sanae (F.M.Bailey) K.D.Hill^[11] previously known as Hoya sanae F.M.Bailey^[12] has leaves less than long, with prominent veins and the edges strongly rolled under. It flowers from May to June.
• Hoya australis subsp. tenuipes (K.D.Hill) P.I.Forst. & Liddle ^[13] is a twining plant has leaves that are leathery, glabrous or sparsely hairy and not curved under, and has extrafloral nectaries. In Australia, this subspecies mainly flowers in September and October.

Distribution and habitat

This species of Hoya is endemic to Australia, and is found in Western Australia, the Northern Territory, Queensland and New South Wales.

Subspecies australis occurs in eastern Australia from the Torres Strait in northern Queensland to Dorrigo in New South Wales.^[14] Subspecies oramicola is restricted to Melville Island|Melville and Bathurst Islands north of Darwin, subsp. rupicola occurs in the Kimberley region of Western Australia and the Top End of the Northern Territory on sandstone outcrops and cliffs.^[15] subsp. sanae grows in foreshore vine thickets on Cape York Peninsula and some offshore islands and subsp. tenuipes is found on the southern Cape York Peninsula, as far south as Innisfail, and in New Guinea, the Solomon Islands and Melanesia.

Ecology

It serves as a food plant for the caterpillars of the Queensland butterfly the no-brand crow (Euploea alcathoe),^[16] and the common Australian crow (E. core).^[17] Flowers are pollinated by the southern grass-dart (Ocybadistes walkeri).^[18]

Use in horticulture

Hoya australia is a popular garden and houseplant in Australia, where it flowers best in a well-lit position. It is often grown in containers and trained to grow on trellises on verandahs, fences and in glasshouses. It is a butterfly-attracting plant in the garden.^[17] It can be grown indoors provided it receives direct sunlight.^[19]

Notes and References

1. Web site: Forster . Paul I. . Liddle . David J. . Hoya australis . Flora of Australia. Australian Biological Resources Study, Department of Climate Change, Energy, the Environment and Water: Canberra. . 2 December 2024.
2. Encyclopedia: Elliot . Rodger W. . Jones . David L. . Blake . Trevor. Encyclopaedia of Australian Plants Suitable for Cultivation . 5, Gr–J. 1990. 386–387 . Lothian Press . Port Melbourne . 0-85091-285-7.
3. Web site: Hoya australis . APNI . 2 December 2024.
4. Traill . James . Descriptions of plants belonging to the genus Hoya . Transactions of the Horticultural Society . 1828 . 7 . 28 . 2 December 2024.
5. Book: Simpson, D.P.. Cassell's Latin Dictionary . Cassell . 1979. 5th. London. 883. 0-304-52257-0.
6. Hill . Ken D. . A revision of Hoya (Asclepiadaceae) in Australia. . Telopea . 1988 . 3 . 2 . 250–252 . 2 December 2024.
7. Forster . Paul I. . Liddle . David J. . Variation in Hoya australis R.Br. ex Traill (Asclepiadaceae). . Austrobaileya . 1991 . 3 . 3 . 508–518 . 2 December 2024.
8. Web site: Hoya australis subsp. australis . Australian Plant Census . 2 December 2024.
9. Web site: Hoya australis subsp. oramicola . Australian Plant Census . 2 December 2024.
10. Web site: Hoya australis subsp. rupicola . Australian Plant Census . 2 December 2024.
11. Web site: Hoya australis subsp. sanae . Australian Plant Census . 2 December 2024.
12. Web site: Hoya sanae . APNI . 2 December 2024.
13. Web site: Hoya australis subsp. tenuipes . Australian Plant Census . 2 December 2024.
14. Web site: Hoya australis subsp. australis . Royal Botanic Garden, Sydney . 2 December 2024.
15. Web site: Hoya australis subsp. rupicola . Northern Territory Government . 3 December 2024.
16. Book: Braby, Michael F.. The Complete Field Guide to Butterflies of Australia . 2005 . CSIRO Publishing . Collingwood, Victoria . 0-643-09027-4 . 194.
17. Book: Clyne, Densey . Densey Clyne

    . Attracting Butterflies to Your Garden . Densey Clyne . 2000. Reed New Holland . Sydney . 1-876334-56-8 . 50.

18. Forster . Paul I.. 1992. Pollination of Hoya australis (Asclepiadaceae) by Ocybadistes walkeri sothis (Lepidoptera: Hesperidae) . Australian Entomological Magazine . 19. 39–43 .
19. Book: Australian Native Plants for Indoors . Ratcliffe . David . Patricia . Ratcliffe . 1987 . Little Hills Press . Crows Nest, NSW . 0-949773-49-2 . 98.