Hoya (plant)
 | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (July 2013) |
| Hoya | |
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| Hoya lanceolata ssp. bella | |
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Gentianales |
| Family: | Apocynaceae |
| Subfamily: | Asclepiadoideae |
| Tribe: | Marsdenieae
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| Genus: | Hoya R.Br. (1810)
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| Species | |
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See text | |
| Synonyms[1] | |
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Hoya is a genus of over 500 accepted species of tropical plants in the dogbane family, Apocynaceae. Most are native to several countries of Asia such as the Philippines, India, Thailand, Malaysia, Vietnam, Bangladesh, Indonesia, Polynesia, New Guinea, and many species are also found in Australia.
Common names for this genus are waxplant, waxvine, waxflower or simply hoya. This genus was named by botanist
Description
Hoyas are
The flowers appear in axillary umbellate clusters at the tip of peduncles. Hoya peduncles are commonly referred to as spurs. In most species these spurs are perennial and are rarely shed. Each flowering cycle increases the length of the spur, and in the larger species can eventually reach 27 cm (11 in) or more. Flowers vary in size from 3 mm (1⁄8 in) (Hoya bilobata Schltr.) to over 95 mm (3+3⁄4 in) (in H. lauterbachii K. Schuman) in diameter. Flower form is typically star-shaped, with five thick, waxy, triangular petals, topped with another star-shaped structure, the corona. Colours on most species range from white to pink; there are species that exhibit yellow to orange, dark reds to near-black, and there are green flowers. Many are sweetly scented. and most produce abundant nectar.
Pollinators include moths, flies, and ants. Pollination is poorly understood, but plants left outdoors in temperate regions do sometimes produce seed, indicating pollination by local insects.
Seeds are borne in twin pods, actually follicles, are generally light, and are dispersed by the wind by means of a small tuft of silky fluff. Germination is rapid, but viability is not long.
At least some species exhibit
Several species exhibit adaptations for
Leaves
Hoya leaves vary in size, texture, colour and venation. In size, leaves range from as small as 5 mm in length and 2 to 4 mm in width (Hoya engleriana Hosseus) to as large as 25 cm by 35 cm. (Hoya latifolia G. Don). Hoya coriacea Blume, has been reported to have leaves as long as two feet in length. There are hoyas with almost perfectly round leaves and others with linear leaves (Hoya linearis Wall. ex. D. Don and Hoya teretifolia Griff. ex Hook. f.). One popular species, Hoya shepherdii Short ex Hook. has leaves that resemble string beans hanging in bunches from their stalks. Hoya linearis Wall. ex D. Don is covered with fine downy hair and resembles masses of Spanish Moss (
Flowers
Hoya flowers are all shaped like five pointed stars. Some species' petals reflex so far that the flowers appear to be round or ball-like. They grow in umbels, or in some species singly (e.g. Hoya Retusa). Umbels can reach impressive proportions in some species, and many species have individual flowers well over 75 mm (3 in) in diameter (H. imperialis Lindl., H. lauterbachii K. Schuman). H. coriacea Blume has been known to have as many as 70 in an inflorescence, each individual measuring nearly 2 cm in diameter with the umbels over 30 cm in breadth. The single-flowered Hoya pauciflora Wight makes up for its paucity by its flower size of nearly 40 mm (1+1⁄2 in) in diameter produced at any time of year. Textures of flower surfaces may be glabrous and shiny, to matte, to finely haired, and some being quite hairy. One of the two clones of Hoya mindorensis Schltr., from the Philippines, comes very close to being a true red. Blue, purples, and violets do not appear to be represented in the genus Hoya. Many varieties of Hoya flowers are fragrant, with various notes such as vanilla, citrus, chocolate, and cinnamon. In some cases the scent can be more noticeable in the morning or evening.
Selected species
Species listed here are given in Albers & Meve (2002) and accepted by both The Plant List and Tropicos.
- Hoya archboldiana – Indonesia, Papua New Guinea
- Hoya australis – Australia, Fiji, Indonesia (Irian Jaya), Papua New Guinea, Solomon Islands, Tonga
- Hoya bhutanica – Bhutan
- Hoya bilobata – Philippines
- Hoya carnosa – S. China, India, Japan, Taiwan, Australia (Queensland), Fiji
- Hoya celebica
- Hoya cinnamomifolia – Indonesia (Java)
- Hoya imbricata – Indonesia (Sulawesi), Philippines
- Hoya kerrii – China, Cambodia, Indonesia (Java), Laos, NW. Thailand, S. Vietnam
- Hoya macgillivrayi – Australia (Queensland)
- Hoya megalaster – Papua New Guinea
- Hoya meliflua – Philippines
- Hoya obscura – Philippines
- Hoya serpens – Australia (Queensland), India (E. Himalaya), Nepal
- Hoya siamica – Cambodia, India, Laos, NW. Thailand, Vietnam
Cultivation and uses
Many species of Hoya are popular houseplants in temperate areas (especially H. carnosa), grown for their attractive foliage and strongly scented flowers. Numerous cultivars have been selected for different leaf forms or flower colours. Hoyas grow well indoors, preferring bright light, but will tolerate fairly low light levels, although they may not flower without bright light. Hoyas commonly sold in nurseries as houseplants include cultivars of H. carnosa (Krimson Queen, Hindu Rope − compacta), H. pubicalyx (often mislabelled as H. carnosa or H. purpurea-fusca), and H. kerrii. Hoyas are easy to propagate, and are commonly sold as cuttings, either rooted or unrooted, or as a potted plant.
Hoya carnosa has been shown in recent studies at the University of Georgia to be an excellent remover of pollutants in the indoor environment.[3]
Various cultures have used hoyas medicinally, especially Polynesian cultures.[citation needed] Some are toxic to livestock and sheep poisonings in Australia are reported.[citation needed]
Several Hoya species and cultivars are excellent terrarium plants.[citation needed]
Rachel Colette Conroy was appointed the International Cultivar Registration Authority for Hoya in 2023.[4]
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Hoya campanulata -
Hoya cinnamomifolia -
Hoya imperialis -
Hoya parasitica -
Hoya pottsii
References
- ^ Hoya R.Br. Plants of the World Online. Retrieved 27 July 2023.
- Robert Brown (1810). Prodromus florae Novae Hollandiae et Insulae Van-Diemen, exhibens characteres plantarum quas annis 1802-1805 per oras utriusque insulae collegit et descripsit Robertus Brown; insertis passim aliis speciebus auctori hucusque cognitis, seu evulgatis, seu ineditis, praaesertim Banksianis, in primo itinere navarchi Cook detectis. Vol. 1. London: Richard Taylor and Biodiversity Heritage Library. p. 459.
- ^ University of Georgia (31 March 2009). UGA research shows some plants can remove indoor pollutants.
- ^ "ICRA Report Sheet". International Society for Horticultural Science. Retrieved 12 October 2023.
Bibliography
- Albers, F. & Meve, U., eds. (2002), Illustrated Handbook of Succulent Plants: Asclepiadaceae, Springer Verlag, ISBN 978-3-540-41964-8
- Christopher, J.T. & Holtum, J.A.M. (1996), "Patterns of Carbon Partitioning in Leaves of Crassulacean Acid Metabolism Species during Deacidification", Plant Physiology, 112 (1): 393–399, PMID 12226397
- Endress, Mary E. & Bruyns, Peter V. (2000), "A revised classification of the Apocynaceae s.l." (PDF), The Botanical Review, 66 (1): 1–56, S2CID 31739212
- Kloppenburg, Dale & Wayman, Ann (2005), The World of Hoyas : a book of pictures (revised ed.), Central Point, OR: Orca Publishing, ISBN 978-0-9630489-4-3
- Liede-Schumann, S. (2006). The Genera of Asclepiadoideae, Secamonoideae and Periplocoideae (Apocynaceae): Descriptions, Illustrations, Identification, and Information Retrieval Version: 21 September 2000.
- Phillips, Roger (1997). The Random House Book of Indoor and Greenhouse Plants (Vol. 2). New York: Random House, Incorporated. ISBN 978-0375750281.
- Trimen, Henry (1888). Hortus Zeylanicus; A Classified List of the Plants, Both Native and Exotic, Growing in the Royal Botanic Gardens. P.R. Deniya. ISBN 9781236067777.
- Yang, Dong Sik; Pennisi, Svoboda V.; Son, Ki-Cheol & Kays, Stanley J. (2009), "Screening Indoor Plants for Volatile Organic Pollutant Removal Efficiency", HortScience, 44 (5): 1377–1381, , retrieved 30 November 2011
- Zachos, Ellen (1997), "Practical Uses of Various Hoya Species"
External links
- Plants of the World Online | Kew Science https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:60437256-2
- Yang, D.S.; Pennisi, S.V.; Son, K.; Kays, S.J. (2009). "Screening Indoor Plants for Volatile Organic Pollutant Removal Efficiency". HortScience. 44 (5): 1377–81. .
- "Hoya R.Br". Atlas of Living Australia.
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