Absolmsia Spartioides

''Hoya'' is a genus of over 500 species of plants in the dogbane family, Apocynaceae, commonly known as waxflowers. 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.

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.

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.

The fruit is a spindle-shaped to oval follicle containing flattened, egg-shaped to oblong seeds with a tuft of hairs at one end.

Taxonomy

The genus was first formally described in 1810 by botanist Robert Brown in his book ''Prodromus Florae Novae Hollandiae et Insulae Van Diemen'', and honours Thomas Hoy, the gardener for the Duke of Northumberland. The first species of ''Hoya'' that Brown described (the type species), was ''Hoya carnosa''.

Species list

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 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.

Various cultures have used hoyas medicinally, especially Polynesian cultures. Some are toxic to livestock and sheep poisonings in Australia are reported.

Several ''Hoya'' species and cultivars are excellent terrarium plants.

Rachel Colette Conroy was appointed the International Cultivar Registration Authority for ''Hoya'' in 2023.

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''

References

Bibliography

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* Liede-Schumann, S. (2006)
''The Genera of Asclepiadoideae, Secamonoideae and Periplocoideae (Apocynaceae): Descriptions, Illustrations, Identification, and Information Retrieval''
Version: 21 September 2000.
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* 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
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{{Authority control

Apocynaceae genera