Editing Rhododendron (section)

====Subgenera====
Terminology from the Sleumer (1949) system is frequently found in older literature, with five subgenera and is as follows;
* Subgenus ''Lepidorrhodium'' Koehne: Lepidotes. 3 sections
* Subgenus ''Eurhododendron'' Maxim.: Elipidotes. 
* Subgenus ''Pseudanthodendron'' Sleumer: Deciduous azaleas. 3 sections
* Subgenus ''Anthodendron'' Rehder & Wilson: Evergreen azaleas. 3 sections
* Subgenus ''Azaleastrum'' Planch.: 4 sections

In the later traditional classification, attributed to Chamberlain (1996), and as used by [[horticulturalists]] and the [[American Rhododendron Society]],{{sfnp|Genus Rhododendron Taxonomic Tree |ref=ARS2}} ''Rhododendron'' has eight subgenera based on [[Morphology (biology)|morphology]], namely the presence of scales (lepidote), [[deciduousness]] of leaves, and the floral and vegetative branching patterns, after Sleumer (1980).{{sfnp|Goetsch |Eckert |Hall|2005 |ref=Goetsch}}{{sfnp|Brown |Craven |Udovicic |Ladiges |2006 |ref=Brown2006}}<ref name=Sleumer80/> These consist of four large and four small subgenera. The first two subgenera (''Rhododendron'' and ''Hymenanthes'') represent the species commonly considered as 'Rhododendrons'. The next two smaller subgenera (''Pentanthera'' and ''Tsutsusi'') represent the 'Azaleas'. The remaining four subgenera contain very few species.<ref name="ARS1"/> The largest of these is subgenus ''Rhododendron'', containing nearly half of all known species and all of the lepidote species.

*Subgenus ''[[Rhododendron subg. Rhododendron|Rhododendron]]'' {{small|L.}}: Small leaf or [[lepidotes]] (scales on the underside of the leaves). 3 sections, 462 species, [[type species]]: ''R.&nbsp;ferrugineum''.
*Subgenus ''[[Rhododendron subg. Hymenanthes|Hymenanthes]]'' {{small|(Blume) K.Koch}}: Large leaf or [[elepidotes]] (without scales). 1 section, 224 species, type [[Rhododendron degronianum|''R.''&nbsp;''degronianum'']].
*Subgenus ''[[Rhododendron subg. Pentanthera|Pentanthera]]'' {{small|(G. Don) Pojarkova}}: Deciduous azaleas. 4 sections, 23 species, type [[Rhododendron luteum|''R.''&nbsp;''luteum'']].
*Subgenus ''[[Rhododendron sect. Tsutsusi|Tsutsusi]]'' {{small|(Sweet) Pojarkova}}: Evergreen azaleas. 2 sections, 80 species, type [[Rhododendron indicum|''R.''&nbsp;''indicum'']].
*Subgenus ''[[Rhododendron subg. Azaleastrum|Azaleastrum]]'' {{small|Planch.}}: 2 sections, 16 species, type ''[[Rhododendron ovatum|R. ovatum]]''.
*Subgenus ''Candidastrum'' {{small|[[Franch.]]}}: 1 species, ''[[Rhododendron albiflorum|R. albiflorum]]''.
*Subgenus ''Mumeazalea'' {{small|(Sleumer) W.R. Philipson & M.N. Philipson}}: 1 species, ''[[Rhododendron semibarbatum]]''.
*Subgenus ''Therorhodion'' {{small|(Maxim.) A. Gray}}: 2 species (''[[Rhododendron camtschaticum]]'', ''[[Rhododendron redowskianun]]'').

For a comparison of the Sleumer and Chamberlain systems, see Goetsch ''et al.'' (2005) Table 1.{{sfnp|Goetsch |Eckert |Hall|2005 |ref=Goetsch}}

This division was based on a number of what were thought to be key morphological characteristics. These included the position of the inflorescence buds (terminal or lateral), whether lepidote or elepidote, deciduousness of leaves, and whether new foliage was derived from [[axils]] from previous year's shoots or the lowest scaly leaves.

[[File:Rhododendron luteum BotGardBln1105Autumn.JPG|thumb|right|Deciduous ''Rhododendron luteum'' in fall color]]
[[File:Rhododendron kaempferi 08.jpg|thumb|Evergreen azalea ''Rhododendron kaempferi'']]
[[File:2014-10-29 13 26 34 Evergreen Rhododendron foliage coloring before being shed in Ewing, New Jersey.JPG|thumb|right|Evergreen azalea cultivar leaf color before shedding]]
[[File:Rhododendron after freezing rain.jpg|thumb|right|Rhododendron after [[freezing rain]]]]
{| class="wikitable"
|+ <big>Morphological classification of ''Rhododendron'' </big><br>(Chamberlain 1996)<ref name=Chamberlain/>
! style="background:#ccf" |Inflorescence buds !!style="background:#ccf" |Leaf scales !!style="background:#ccf" |Leaf shoots !!style="border-right:solid black 2px; background:#ccf" |Leaves !!style="background:#ccf" |Subgenus !!style="background:#ccf" |Section
|-
|rowspan=7| Terminal ||colspan=3|Present ||style="border-left:solid black 2px"|''[[Rhododendron subg. Rhododendron|Rhododendron]]''
|-
| rowspan=6 |Absent||rowspan=4|Previous year||style="border-right:solid black 2px" |Evergreen||''[[Rhododendron subg. Hymenanthes|Hymenanthes]]''
|-
| rowspan=3 style="border-right:solid black 2px"|Deciduous||rowspan=3|''[[Rhododendron subg. Pentanthera|Pentanthera]]'' ||''Pentanthera''
|-
| ''Rhodora''
|-
| ''Viscidula''
|-
|rowspan=2 colspan=2|Lowest leaves|| style="border-left:solid black 2px"|''Pentanthera''||''Sciadorhodion''
|-
| style="border-left:solid black 2px"|''[[Rhododendron sect. Tsutsusi|Tsutsusi]]''
|-
|rowspan=4 colspan=3|Lateral|| style="border-right:solid black 2px"|Evergreen||''[[Rhododendron subg. Azaleastrum|Azaleastrum]]''
|-
| rowspan=3 style="border-right:solid black 2px"|Deciduous||''Candidastrum''
|-
| ''Mumeazalea''
|-
|''Therorhodion''
|}

Following the [[cladistic analysis]] of Goetsch ''et al.'' (2005){{sfnp|Goetsch |Eckert |Hall|2005 |ref=Goetsch}} this scheme was simplified, based on the discovery of three major [[clade]]s (A, B, C) as follows.

'''Clade A'''
* Subgenus ''[[Rhododendron subg. Rhododendron|Rhododendron]]'' {{Small|L.}}: Small leaf or [[lepidotes]] (scales on the underside of the leaves). 3 sections, about 400 species, [[type species]]: ''R.''&nbsp;''ferrugineum''.
* Subgenus ''[[Rhododendron subg. Choniastrum|Choniastrum]]'' {{Small|Franch.}}: 11 species
'''Clade B'''
* Subgenus ''[[Rhododendron subg. Hymenanthes|Hymenanthes]]'' {{Small|(Blume) K.Koch}}: Large leaf or [[elepidotes]] (without scales), including deciduous azaleas. 2 sections, about 140–225 species, type ''[[Rhododendron degronianum|R. degronianum]]''.
'''Clade C'''
* Subgenus ''[[Rhododendron subg. Azaleastrum|Azaleastrum]]'' {{Small|Planch.}}: Evergreen azaleas. 3 sections, about 120 species, type ''[[Rhododendron ovatum]]''.
'''[[Sister taxon]]'''
* Subgenus ''Therorhodion'' {{Small|(Maxim.) A. Gray}}: 2 species (''[[Rhododendron camtschaticum|R. camtschaticum]]'' and ''[[Rhododendron redowskianun|R. redowskianun]]'').