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 is: Scales sessile or sometimes stalked, lobed to deeply incised or sometimes entire; corolla campanulate, trumpet-like, salver-shaped, tubular or funnel-shaped; stamens 10, 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 subgenusRhododendron, 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 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, Subgenus Vireya, Section Schistanthe, or the majority of the Malesian tropical rhododendrons.. Goetsch 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, found a lack of support for monophyly of these subsections, and rather a series of clades based on geographical distribution:
R. subsect. Albovireya Sleumer, typeRhododendron album Blume
R. subsect. Euvireya Copel.f., type Rhododendron javanicum Benn
R. subsect. Malayovireya Sleumer, type Rhododendron malayanum Jack
R. subsect. Phaeovireya Sleumer, type Rhododendron beyerinckianum Koord.
R. subsect. Pseudovireya Clarke, type Rhododendron vaccinioides Hook.f.
R. subsect. Siphonovireya Sleumer, type Rhododendron habbemae Koord
R. subsect. Solenovireya Copel.f., type Rhododendron jasminiflorum Hook.
In Argent's treatment of Vireya as a subgenus, he included seven sections, with Euvireyaconsisting of five subsections, but this is not supported by phylogenetic analysis. These studies, for instance that of Hall, 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 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, Table1. Thus the new subsection structure is:
R. subsect. Euvireya Copel.f., type Rhododendron javanicum Benn
R. subsect. Malayovireya Sleumer, type Rhododendron malayanum Jack
Characteristics:
Euvireya – Scales sessile or stalked, scattered or dense, not of two obviously different size classes, lobed to deeply incised and the centre not dark-coloured.
Malayovireya – Scales sessile, dense, of two obviously different size classes, lobed and the centre dark-coloured.
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. Found in that area an outstanding specimenRhododendron loranthiflorum has been named after the New YorkguruSri Chinmoy.
