Rank Section | Subfamily Ericoideae | |
 | ||
Similar Rhododendron lochiae, Rhododendron laetum, Rhododendron subg Pentanthera, Lepidotes, Rhododendron | ||
Rhododendron section Vireya (vireyas) is a tropical group of Rhododendron species, numbering about 300 in all. Vireyas are native to southeastern Asia and range from Thailand to Australia.
Contents
Description
Vireya are morphologically diverse, and characterised by seeds with tailed appendages, the presence of leaf 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 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 subgenus rather than as here, a section of the Rhododendron subgenus. 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 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 et al, using phylogenetic analysis found a lack of support for monophyly of these subsections, and rather a series of clades based on geographical distribution:
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 to the other six subsections, while the Malesian species within Pseudovireya also formed an outgroup, resulting in three major clades. Thus Craven et al. 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), Table 1.
Thus the new subsection structure is:
Characteristics:(Craven 2008)
Distribution
Vireya are found throughout the Malesian Archipelago. Malesian species are found in all subsections, while species from other areas appear only in Euvvireya, Malayovireya and Pseudovireya.