''Vireya'' rhododendron ''Rhododendron'' section ''Vireya'' (vireyas) is a tropical group of ''

Rhododendron ''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the Ericaceae, heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan ...

'' species, numbering about 300 in all. The group may also be treated as ''Rhododendron'' subgenus ''Vireya''. Vireyas are native to

southeastern Asia Southeast Asia is the geographical southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Australian mainland, which is part of Oceania. Southeast Asia is ...

and range from

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Description

''Vireya'' are morphologically diverse, and characterised by

seeds In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be sown, which may include seed and husk or tuber. Seeds are the ...

with tailed appendages, the presence of

leaf A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...

idioblasts and capsule valves which twist upon opening. The formal description (Craven 2008) is: Scales sessile or sometimes stalked, lobed to deeply incised or sometimes entire; corolla campanulate, trumpet-like, salver-shaped, tubular or funnel-shaped; stamens (5–)10(–16), exserted to included, staminal filaments glabrous or hairy from the base; capsule valves twisting after dehiscence; seeds with a distinct tail at each end.

Taxonomy

''Vireya'' is the largest of the three sections constituting

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

''Rhododendron'', and includes about a third of all ''Rhododendron'' species. The exact classification has varied among various authors, some authors considering ''Vireya'' to be a separate

rather than as here, a

section Section, Sectioning, or Sectioned may refer to: Arts, entertainment and media * Section (music), a complete, but not independent, musical idea * Section (typography), a subdivision, especially of a chapter, in books and documents ** Section sig ...

of the subgenus ''Rhododendron''. It has been suggested that taxonomic nomenclatural correctness requires changing the name of the ''Vireya'' rhododendrons to ''Schistanthe''. Thus the term 'Vireya' has been used to refer to Section ''Vireya'' (Sleumer), Subgenus ''Vireya'', Section ''Schistanthe'', or the majority of the

Malesian Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalayan and Australasian realms. It is a phytogeographical floristic region in the Paleotropical kingdom. It was first recognized as a distinct region in ...

tropical rhododendrons. (Fayaz). Goetsch (2011) gives the number of species as 320, and the total taxa including subspecies, forms and varieties as 380.

Subdivision

The section has traditionally been considered to consist of seven subsections based on morphology, although Brown etal., using

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

, found a lack of support for

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

of these subsections, and rather a series of

clades In biology, a clade (), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy ...

based on geographical distribution: * R. subsect. ''Albovireya'' Sleumer, type ''

Rhododendron album ''Rhododendron album'' is a species of plant in the family Ericaceae. It is Endemism, endemic to Java in Indonesia. It is a vulnerable species threatened by habitat loss. Description ''Rhododendron album'' is white, but can also appear lilac ...

'' Blume * R. subsect. ''Euvireya'' Copel.f., type ''

Rhododendron javanicum ''Rhododendron javanicum'' is a rhododendron species native to Indonesia, Malaysia, and the Philippines. This evergreen shrub grows to with bright orange flowers in spring. Plants may be terrestrial or epiphyte, epiphytic. Some forms from the Ph ...

'' (Blume) Benn * R. subsect. ''Malayovireya'' Sleumer, type '' Rhododendron malayanum'' Jack * R. subsect. ''Phaeovireya'' Sleumer, type ''

Rhododendron beyerinckianum ''Rhododendron beyerinckianum'' is a species of rhododendron endemic to New Guinea. It is found in the Indonesian portion of the island and western Papua New Guinea, extending as far east as Mount Victoria and Mount Dayman, where it grows at e ...

'' Koord. * R. subsect. ''Pseudovireya'' Clarke, type ''

Rhododendron vaccinioides ''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan region, bu ...

'' Hook.f. * R. subsect. ''Siphonovireya'' Sleumer, type ''

Rhododendron habbemae ''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the Ericaceae, heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan ...

'' Koord * R. subsect. ''Solenovireya'' Copel.f., type ''

Rhododendron jasminiflorum ''Rhododendron jasminiflorum'' is a rhododendron species native to Peninsular Malaysia, Borneo, Sumatra, and the Philippines. Description Growing to in height, it is an evergreen shrub with clusters of slightly fragrant, narrowly trumpet-shaped ...

'' Hook. In Argent's (2006) treatment of Vireya as a subgenus, he included seven sections, with ''Euvireya'' consisting of five subsections, but this is not supported by phylogenetic analysis. These studies, for instance that of Hall (2006), suggested a very different approach. The Asian mainland species represented by ''Pseudovireya'' appear as a

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the other six subsections, while the Malesian species within ''Pseudovireya'' also formed an

outgroup Outgroup may refer to: * Outgroup (cladistics), an evolutionary-history concept * Outgroup (sociology) In social psychology and sociology, an in-group is a social group to which a person psychologically identifies as being a member. By cont ...

, resulting in three major

. Thus Craven etal. proposed there be only two subsections of ''Vireya'', corresponding to the core species, ''Euvireya'' and the much smaller ''Malayovireya'', while the other two groups formed out of ''Pseudovireya'' be raised to section rank, keeping the original name ''Pseudovireya'' for the mainland species, and using Argent's name, ''Discovireya'' for the Malesian species. For a comparison of the Sleumer, Argent and Craven schemata, see Craven (2008), Table1. Thus the new subsection structure is: * R. subsect. ''Euvireya'' Copel.f., type ''Rhododendron javanicum'' (Blume) Benn * R. subsect. ''Malayovireya'' Sleumer, type '' Rhododendron malayanum'' Jack Characteristics:(Craven 2008) * ''Euvireya'' – Scales sessile or stalked, scattered or dense, not of two obviously different size classes, lobed to deeply incised (or sometimes entire) and the centre not dark-coloured. * ''Malayovireya'' – Scales sessile, dense, of two obviously different size classes, lobed and the centre dark-coloured. ,

World Flora Online World Flora Online is an Internet-based compendium of the world's plant species. Description The World Flora Online (WFO) is an open-access database, launched in October 2012 as a follow-up project to The Plant List, with the aim of publishi ...

treated the group as ''R.'' subg.''Vireya'', divided into seven sections: * section ''Albovireya'' * section ''Discovireya'' * section ''Hadranthe'' * section ''Malayovireya'' * section ''Pseudovireya'' * section ''Schistanthe'' * section ''Siphonovireya''

Distribution

''Vireya'' are found throughout the

Malesian Archipelago Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalayan and Australasian realms. It is a phytogeographical floristic region in the Paleotropical kingdom. It was first recognized as a distinct region in ...

– Peninsular Malaysia, Sumatra, Borneo, Java, the Philippines, Sulawesi, the Lesser Sunda Islands, and Maluku – and in

Papuasia Papuasia is a Level 2 botanical region defined in the World Geographical Scheme for Recording Plant Distributions (WGSRPD). It lies in the southwestern Pacific Ocean, in the Melanesia ecoregion of Oceania and Tropical Asia. It comprises th ...

, which includes New Guinea, the Bismarck Archipelago, and the Solomon Islands. Some ''Vireya'' species also occur in Australia, China, India, Nepal, Taiwan, and Vietnam. Only a few non-''Vireya'' species occur in Malesia, in the Malay Peninsula, Sumatra, and the Philippines. Malesian species are found in all subsections, while species from other areas appear only in ''Euvvireya'', ''Malayovireya'' and ''Pseudovireya''.

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

has the most ''Vireya'' species of any island, with 167 species. Borneo has 46 species, the second most of any island.G. Argent (1985) Vireya Rhododendrons in Borneo. ''Notes from the Royal Botanic Garden, Edinburgh'' 43 53–61

References

Bibliography

Chris Callard. The History of Vireya Rhododendron Culture. Vireya Rhododendrons. 1998 onwards

L.A. Craven, F. Danet, J.F. Veldkamp, L.A. Goetsch, B.D. Hall. Vireya Rhododendrons: their monophyly and classification (''Ericaceae'', ''Rhododendron'' section ''Schistanthe''). Blumea 56, 2011: 153–158. 2011

Goetsch, L.A., Craven, L.A. and Hall B.D. 2011. Major speciation accompanied the dispersal of Vireya Rhododendrons (Ericaceae, Rhododendron sect. Schistanthe) through the Malayan archipelago: Evidence from nuclear gene sequences. Taxon 60 (4): 1015–1028.

* ttps://www.rhododendron.org/vireya/archive.htm Peter Adams. Evolution, Adaptive Radiation and Vireya Rhododendrons - Part I. JARS SPRING 2013 pp. 74-76
Biodiversity of the Vireya group of ''Rhododendron'' L. (Ericaceae) collections in New Zealand and their potential contribution to international conservation. Fayaz A. PhD Thesis, Department of Plant Science, Massey University, New Zealand. 2012

External links

* {{Taxonbar, from=Q7321173 *Vireya Plant sections Flora of Malesia Flora of Papuasia