{{Short description|Genus of flowering plants}} {{Use dmy dates|date=July 2023}} {{Automatic taxobox |image = Hoyabella_092005.jpg |image_caption = ''Hoya lanceolata'' subsp. ''bella'' |display_parents = 2 |taxon = Hoya |authority = R.Br.<ref name="POWO">{{cite web |title=''Hoya'' |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:60437256-2#synonyms |publisher=Plants of the World Online |access-date=27 November 2024}}</ref> |subdivision_ranks = Species |subdivision = See List of ''Hoya'' species |synonyms_ref = <ref name="POWO"/> |synonyms = * ''Absolmsia'' {{small|Kuntze (1891), nom. superfl.}} * ''Acanthostemma'' {{small|Blume (1849)}} * ''Anatropanthus'' {{small|Schltr. (1908)}} * ''Antiostelma'' {{small|(Tsiang & P.T.Li) P.T.Li (1992)}} * ''Astrostemma'' {{small|Benth. (1880)}} * ''Cathetostemma'' {{small|Blume (1849)}} * ''Centrostemma'' {{small|Decne. (1838)}} * ''Clemensia'' {{small|Schltr. (1915), nom. illeg.}} * ''Clemensiella'' {{small|Schltr. (1915)}} * ''Codonanthus'' {{small|Hassk. (1842)}} * ''Cyrtoceras'' {{small|Benn. (1838)}} * ''Cystidianthus'' {{small|Hassk. (1843)}} * ''Eriostemma'' {{small|(Schltr.) Kloppenb. & Gilding (2001)}} * ''Hiepia'' {{small|V.T.Pham & Aver. (2011)}} * ''Madangia'' {{small|P.I.Forst., Liddle & I.M.Liddle (1997)}} * ''Micholitzia'' {{small|N.E.Br. (1909)}} * ''Otostemma'' {{small|Blume (1849)}} * ''Physostelma'' {{small|Wight (1834)}} * ''Plocostemma'' {{small|Blume (1849)}} * ''Pterostelma'' {{small|Wight (1834)}} * ''Schollia'' {{small|J.Jacq. (1811)}} * ''Sperlingia'' {{small|Martin Vahl (1810)}} * ''Triacma'' {{small|Hasselt ex Miq. (1857)}} * ''Triplosperma'' {{small|G.Don (1837)}} }} [[File:Hoya carnosa - flower view 01.jpg|thumb|right|''Hoya carnosa'']] [[File:Hoya mindorensis 2024.jpg|thumb|''Hoya mindorensis'', Sydney, Australia.]]
'''''Hoya''''' is a genus of over 500 species of plants in the dogbane family, Apocynaceae, commonly known as '''waxflowers'''.<ref name="FoA">{{cite web |last1=Forster |first1=Paul Irwin |last2=Liddle |first2=David J. |title=''Hoya'' |url=https://profiles.ala.org.au/opus/foa/profile/Hoya |publisher=Flora of Australia. Australian Biological Resources Study, Department of Climate Change, Energy, the Environment and Water: Canberra. |access-date=27 November 2024}}</ref> Plants in the genus ''Hoya'' are mostly epiphytic or lithophytic vines, rarely subshrubs, with leathery, fleshy or succulent leaves, shortly tube-shaped or bell-shaped flowers with five horizontally spreading lobes, the flowers in umbels or racemes, and spindle-shaped or cylindrical to oval follicles containing flattened egg-shaped to oblong seeds.<ref name="FoA" /><ref name="RBGS">{{cite web |last1=Harden |first1=Gwen J. |last2=Williams |first2=John B. |title=Genus ''Hoya'' |url=https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&showsyn=&dist=&constat=&lvl=gn&name=Hoya |publisher=Royal Botanic Garden, Sydney |access-date=27 November 2024}}</ref><ref name="NT">{{cite web |title=''Hoya'' |url=https://eflora.nt.gov.au/factsheetGenus?id=394 |publisher=Northern Territory Government |access-date=27 November 2024}}</ref>
==Description== Plants in the genus ''Hoya'' are mostly epiphytic or lithophytic vines that rarely form roots in the ground, or rarely more or less shrubby. They have creeping or climbing, pendent, left-twining stems, with white latex, and sometimes with adventitious roots. The stems are cylindrical in cross section, and more or less sparsely branched. The leaves are leathery, often fleshy or succulent, elliptic, egg-shaped, rhomboid or lance-shaped, may be glabrous or hairy, and usually have a petiole.<ref name="FoA" /><ref name="RBGS" /><ref name="NT" /><ref name="Albers">{{cite book |editor-last1=Albers |editor-first1=Focke |editor-last2=Meve |editor-first2=Ulrich |title=Illustrated Handbook of Succulent Plants |date=2004 |publisher=Springer-Verlag |location=Berlin |volume=4 |pages=147–148 |isbn=978-3-540-41964-8 |url=https://books.google.com/books?id=CpSWiIQZLnEC&q=Hoya |access-date=29 November 2024}}</ref><ref name=FB>{{FloraBase|name=''Hoya''|id=21946}}</ref>
The flowers are often fleshy or waxy, arranged in umbels or racemes on a peduncle between the leaves, the peduncle usually persisting from year to year. The petals are wheel-shaped or tube-shaped, with five fleshy, more or less jug-shaped, horizontally spreading lobes attached to the staminal column, and forming a prominent ring alternating with the petal lobes.<ref name="FoA" /><ref name="RBGS" /><ref name="NT" /><ref name="Albers" /><ref name="FB" />
The fruit is a spindle-shaped to oval follicle containing flattened, egg-shaped to oblong seeds with a tuft of hairs at one end.<ref name="FoA" /><ref name="NT" /><ref name="Albers" />
==Taxonomy== The genus was first formally described in 1810 by botanist Robert Brown in his book ''Prodromus Florae Novae Hollandiae et Insulae Van Diemen'',<ref name="R.Br.">{{cite book |last1=Brown |first1=Robert |title=Prodromus Florae Novae Hollandiae et Insulae Van Diemen |date=1810 |publisher=Typis R Taylor, veneunt apud J. Johnson |location=London |pages=459–460 |url=https://www.biodiversitylibrary.org/item/29583#page/327/mode/1up |access-date=27 November 2024}}</ref> and honours Thomas Hoy, the gardener for the Duke of Northumberland.<ref name="FoA" /> The first species of ''Hoya'' that Brown described (the type species), was ''Hoya carnosa''.<ref name="R.Br." />
===Species list=== {{Main|List of Hoya species}}
==Use in horticulture== 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'' ('Tricolor', 'Rubra' & 'Compacta'), ''H. pubicalyx'' (often mislabelled as ''H. carnosa'' or ''H. purpurea-fusca''), and ''H. kerrii''. Hoyas are easy to propagate, and are commonly grown as a hanging basket or as a potted plant.<ref> {{cite web |title=Hoya - North Carolina State Extension Gardener Plant Toolbox |url=https://plants.ces.ncsu.edu/plants/hoya/common-name/hoya/ |publisher=North Carolina State Extension |access-date=7 May 2026}} </ref>
''Hoya carnosa'' has been shown in recent studies at the University of Georgia to be an excellent remover of pollutants in the indoor environment.<ref name="UGA">{{cite news |title=UGA research shows some plants can remove indoor pollutants |url=https://news.uga.edu/some-plants-remove-indoor-pollutants/ |access-date=27 November 2024 |agency=UGA Today |publisher=University of Georgia |date=31 March 2009}}</ref>
Various cultures have extensively used hoyas medicinally, leading to a significant decrease in population in some parts of the world.<ref>{{Cite journal |last=Alam |first=Naushad |last2=Siddique |first2=Waseem |last3=Mishra |first3=Manoj K. |last4=Pandey |first4=Anukriti |last5=Purshottam |first5=Dhermendra K. |last6=Singh |first6=Khuraijam Jibankumar |last7=Tewari |first7=Shri Krishna |last8=Chakrabarty |first8=Debasis |date=2023-03-01 |title=Micropropagation of Hoya carnosa, H. kerrii, H. parasitica, and H. longifolia using tray-based floating and stationary hydroponic systems |url=https://www.sciencedirect.com/science/article/pii/S030442382200913X |journal=Scientia Horticulturae |volume=311 |article-number=111804 |doi=10.1016/j.scienta.2022.111804 |issn=0304-4238|url-access=subscription }}</ref>
Some species, (notably ''Hoya australis)'' are very toxic to livestock with sheep poisonings in Australia having been reported.<ref>{{Cite journal |last=Legg |first=J |last2=White |first2=C.T. |date=22 May 1940 |title=''Hoya australis'': a Plant Poisonous to Stock. |journal=Australian Veterinary Journal |volume=89 |issue=11 |doi=10.1111/avj.2011.89.issue-11 |issn=0005-0423 |via=CABI digital library}}</ref>
Several ''Hoya'' species and cultivars are excellent terrarium plants.{{citation needed|date=July 2023}}
Rachel Colette Conroy was appointed the International Cultivar Registration Authority for ''Hoya'' in 2023.<ref>{{cite web |title=ICRA Report Sheet |url=https://www.ishs.org/sci/icralist/111.htm |publisher=International Society for Horticultural Science |access-date=12 October 2023}}</ref>
<gallery> File:Hoya campanulata Bot. Reg. 33.54.jpg|''Hoya campanulata'' File:Hoya cinnamomifolia.jpg|''Hoya cinnamomifolia'' File:Hoya imperialis.jpg|''Hoya imperialis'' File:Hoya parasitica Paxton 023.jpg|''Hoya parasitica'' File:Hoya pottsii Curtis Botanical Magazine pl.3425.jpg|''Hoya pottsii'' </gallery>
==References== {{Reflist}}
===Bibliography=== * {{Citation |last1=Christopher |first1=J.T. |last2=Holtum |first2=J.A.M. |year=1996 |title=Patterns of Carbon Partitioning in Leaves of Crassulacean Acid Metabolism Species during Deacidification |journal=Plant Physiology |volume=112 |issue=1 |pages=393–399 |doi=10.1104/pp.112.1.393 |name-list-style=amp |pmid=12226397 |pmc=157961}} * {{Citation |last1=Endress |first1=Mary E. |last2=Bruyns |first2=Peter V. |year=2000 |title=A revised classification of the Apocynaceae s.l. |journal=The Botanical Review |volume=66 |issue=1 |pages=1–56 |doi=10.1007/BF02857781 |bibcode=2000BotRv..66....1E |s2cid=31739212 |name-list-style=amp |url=https://www.zora.uzh.ch/id/eprint/156540/1/ZORA_NL_156540.pdf }} * {{Citation |last1=Kloppenburg |first1=Dale |last2=Wayman |first2=Ann |year=2005 |title=The World of Hoyas: a book of pictures |edition=revised |location=Central Point, OR |publisher= Orca Publishing |isbn=978-0-9630489-4-3 |name-list-style=amp }} * Liede-Schumann, S. (2006). [https://web.archive.org/web/20070708221010/http://www.uni-bayreuth.de/departments/planta2/research/databases/delta_as/index.htm ''The Genera of Asclepiadoideae, Secamonoideae and Periplocoideae (Apocynaceae): Descriptions, Illustrations, Identification, and Information Retrieval''] Version: 21 September 2000. * {{cite book|last=Phillips|first=Roger|title=The Random House Book of Indoor and Greenhouse Plants (Vol. 2)|year=1997|publisher=Random House, Incorporated|location=New York |isbn=978-0-375-75028-1}} * {{cite book|last=Trimen|first=Henry|title=Hortus Zeylanicus; A Classified List of the Plants, Both Native and Exotic, Growing in the Royal Botanic Gardens|year=1888|publisher=P.R. Deniya|isbn=978-1-236-06777-7}} * {{Citation |last1=Yang |first1=Dong Sik |last2=Pennisi |first2=Svoboda V. |last3=Son |first3=Ki-Cheol |last4=Kays |first4=Stanley J. |year=2009 |title=Screening Indoor Plants for Volatile Organic Pollutant Removal Efficiency |journal=HortScience |volume=44 |issue=5 |pages=1377–1381 |url=http://hortsci.ashspublications.org/content/44/5/1377.abstract |access-date=2011-11-30 |name-list-style=amp |doi=10.21273/HORTSCI.44.5.1377 |doi-access=free }} * Zachos, Ellen (1997), "Practical Uses of Various Hoya Species" <!-- Only ref I can find is "Zachos E (1998) Practical uses of various Hoya species. The Hoyan 19 (4)/20 (1): part II: 6-10/ 3-8." Not sure what the odd page numbers mean! -->
==External links== {{Commons category|Hoya (genus)|Hoya}} * Plants of the World Online | Kew Science https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:60437256-2 *{{cite journal |last1=Yang |first1=D.S. |last2=Pennisi |first2=S.V. |last3=Son |first3=K. |last4=Kays |first4=S.J. |title=Screening Indoor Plants for Volatile Organic Pollutant Removal Efficiency |journal=HortScience |volume=44 |issue=5 |pages=1377–81 |date=2009 |doi=10.21273/HORTSCI.44.5.1377 |url=https://journals.ashs.org/hortsci/view/journals/hortsci/44/5/article-p1377.xml|doi-access=free }} *{{cite web |title=''Hoya'' R.Br. |work=Atlas of Living Australia |url=https://bie.ala.org.au/species/https://id.biodiversity.org.au/taxon/apni/51266755}}
{{Taxonbar|from=Q157749}} {{Authority control}}
Category:Hoya Category:Apocynaceae genera