Genus Rhododendron New Classification

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Classification

Rhododendrons belong to the Ericaceae or heath family. Other members of the Ericaceae include the heaths (Erica), and heathers (Calluna), mountain laurel (Kalmia), lily-of-the-valley shrub (Pieris), cranberry (Vaccinium), Leucothoe and Andromeda. Almost all of the heath family make good garden plants.

When Linnaeus created the botanical grouping called genus Rhododendron in 1753, he created a separate genus for Azaleas containing 6 species. In 1796 Salisbury pointed out that Azaleas and Rhododendrons could not be maintained as distinct genera. In 1834, George Don subdivided the genus Rhododendron into 8 sections that were recognized until 2004. Azaleas comprised two of these sections, Subgenus Pentanthera typified by Rhododendron nudiflorum and Subgenus Tsutsusi typified by Rhododendron Tsutsusi.

The extensive collections of Rhododendron in the early 1900's from southern Asia made by Forrest, Rock, Kingdom-Ward, and others stimulated taxonomic work at Edinburgh Botanic Garden and Herbarium under the direction of Bayley Balfour. The horticulturally based classification consists of about 45 series. The artificial classification was intended as a temporary measure, but it became firmly entrenched following the publication of The Species of Rhododendron in 1930 by the Royal Horticultural Society. This system was designed to cope with the vast quantities of new plant material received from the Orient, North America, etc. Balfour intended to revise the temporary system but died before it could be accomplished.

The Series system does not attempt to classify species under their subgenera and section as proposed in the International Rules of Botanical Nomenclature. Further, it is based largely on cultivated plants rather than Rhododendron found in the wild.

The Eight Subgenera prior to 2004

With many species discovered over several centuries the genus Rhododendron has been subdivided into groups and revised several times. . Up until 2004 the genus was divided into eight subgenera under the taxonomic system of Chamberlain et al. (1996):

  1. Rhododendron (lepidote rhododendrons and vireyas)
  2. Hymenanthes (elepidote rhododendrons)
  3. Pentanthera (elepidote deciduous azaleas)
  4. Tsutsusi (elepidote evergreen azaleas)
  5. Azaleastrum (R. ovatum and R. stamineum)
  6. Candidastrum (R. albiflorum)
  7. Mumeazalea (R. semibarbatum)
  8. Therorhodion (R. camtshaticum)

The first four of these subgenera contain all species the entire genus except for five. Of the last four Candidastrum, Mumeazalea and Therorhodion each include only one species (R. albiflorum, R. semibarbatum and R. camtshaticum respectively) while Azaleastrum includes two species (R. ovatum and R. stamineum).

Subgenera Rhododendron and Hymenanthes include the plants that gardeners recognize as the "true" rhododendrons. Some of these, the lepidote rhododendrons, have small scales on their leaves and make up the subgenus Rhododendron. Elepidote rhododendrons, those without leaf scales, form the subgenus Hymenanthes.

Subgenus Pentanthera covered the deciduous azaleas and Tsutsusi covered the evergreen azaleas. Neither of these Subgenus has scales.

A list of all species and their classification is provided in the Genus Rhododendron Taxonomic Tree

The Five Subgenera proposed in 2004

Based upon genetic and chemical data, in 2004, Loretta Goetsch, Andrew Eckert and Benjamin Hall of the University of Washington proposed and in 2005 published a recommendation that the genus Rhododendron be revised and subdivided into five subgenera:

  1. Hymenanthes (elepidote rhododendrons & deciduous azaleas)
  2. Azaleastrum (evergreen & deciduous azaleas)
  3. Choniastrum (R. championae, R. hancockii, R. latoucheae, R. moulmainense, R. stamineum)
  4. Therorhodion (R. camtschaticum)
  5. Rhododendron (lepidote rhododendrons & vireyas)

Some of the subgenera are divided into sections, which are further divided into subsections.

For taxa outside of subgenus Rhododendron, this system eliminates three subgenera and two sections that are present in the 1996 taxonomic system of Chamberlain et al.

Section Pentanthera is included within subgenus Hymenanthes.

Sections Sciadorhodion and Viscidula and R. vaseyi (section Rhodora) from the discontinued subgenus Pentanthera are combined with sections Azaleastrum, Tsutsusi and Brachycalyx to form an expanded and revised subgenus Azaleastrum. Sister groups in this subgenus are the sections Tsutsusi (largely evergreen) and Sciadorhodion (entirely deciduous)

Since Choniastrum lacks lepidote scales on the leaves, Goetsch et al. propose that Choniastrum be considered a separate subgenus.

After Dr. Hall presented this work at the ARS National Meeting in 2005, Norman Todd published a paper called "Hall's DNA". In this paper Todd states: "the DNA results obtained by Ben Hall do not support Pentanthera being a subgenus.  He proposes that it now become part of Hymenanthes.  The genetic differences are not significant enough to warrant sub generic rank.  The ranking below Subgenus is Section. Hall proposes that Pentanthera  be given a Section ranking.  He proposes other changes in the other smaller subgenera ..."

If you understand the basic ideas of genus, subgenus, section and species you will have a better understanding of rhododendron naming conventions. A rhododendron species can be uniquely identified with the genus and species. Hence Rhododendron albiflorum defines a unique species. There may be another genus that uses the name albiflorum since it is Latin for "white flowering". Return to Top

Proposed Genus Rhododendron Taxonomic Tree

This version of a proposed Taxonomic Tree of 785 species is based upon the similar tree published at:

http://www.flounder.ca/FraserSouth/tree.asp as updated on March 16, 2011 when L. A. Craven showed that genera Diplarche and Menziesia should be nested in genus Rhododendron in section Sciadohodion based upon cladistic analyses of DNA data. [Blumea 56, 2011: 33-35]

The place of the following 2 species from genus Diplarche in genus Rhododendron has not been determined:

Rhododendron chamberlainii, formerly Diplarche multiflora
Rhododendron sophistarum, formerly Diplarche pauciflora

SUBGENUS SECTION SUBSECTION SPECIES SUBSPECIES VARIETY
subgenus Azaleastrum
section Sciadorhodion
Rhododendron albiflorum
Rhododendron albrechtii
Rhododendron benhallii
Rhododendron goyozanense
Rhododendron katsumatae
Rhododendron kroniae
Rhododendron menziesii
ssp. glabellum
Rhododendron multiflorum
forma bicolor
forma brevicalyx
var. purpureum
Rhododendron pentaphyllum
Rhododendron pentandrum
Rhododendron pentaphyllum
Rhododendron pilosum
Rhododendron schlippenbachii
Rhododendron vaseyi
Rhododendron yakushimense
section Tsutsusi
Rhododendron amagianum
Rhododendron atrovirens
Rhododendron breviperulatum
Rhododendron decandrum
Rhododendron dilatatum
Rhododendron eriocarpum
Rhododendron farrerae
Rhododendron hidakanum
Rhododendron hongkongense
Rhododendron indicum
Rhododendron kaempferi
Rhododendron kanehirai
Rhododendron kiusianum
var. kiusianum
var. sataense
Rhododendron kiyosumense
Rhododendron leptothrium
Rhododendron mariesii
Rhododendron mayebarae
Rhododendron microphyton
Rhododendron mucronatum
var. mucronatum
Rhododendron nakaharae
Rhododendron noriakianum
var. lagopus
ssp. niphophilum
ssp. nudipes
Rhododendron nudipes
ssp. nupides
ssp. niphophilum
Rhododendron oldhamii
Rhododendron ovatum
Rhododendron reticulatum
Rhododendron ripense
Rhododendron rubropilosum
Rhododendron sanctum
Rhododendron saxicolum
Rhododendron scabrum
Rhododendron semibarbatum
Rhododendron serpyllifolium
Rhododendron simsii
Rhododendron stenopetalum
Rhododendron subsessile
Rhododendron tashiroi
Rhododendron tosaense
Rhododendron tschonskii
Rhododendron tsuiophyllum
Rhododendron vialii
Rhododendron viscistylum
Rhododendron wadanum
Rhododendron weyrichii
Rhododendron yedoense
var. poukhanense
Rhododendron nipponicum
subgenus Choniastrum
Rhododendron championae
Rhododendron hancockii
Rhododendron latoucheae
Rhododendron moulmainense
Rhododendron stamineum
subgenus Hymenanthes
section Pentanthera
Rhododendron alabamense
Rhododendron arborescens
Rhododendron atlanticum
Rhododendron austrinum
Rhododendron calendulaceum
Rhododendron canadense
Rhododendron canescens
Rhododendron colemanii
Rhododendron cumberlandense
Rhododendron eastmanii
Rhododendron flammeum
Rhododendron luteum
Rhododendron molle
ssp. molle
ssp. japonicum
Rhododendron occidentale
Rhododendron periclymenoides
Rhododendron prinophyllum
Rhododendron prunifolium
Rhododendron viscosum
section Ponticum
subsection Arborea
Rhododendron arboreum
ssp. albotomentosum
ssp. arboreum
ssp. cinnamomeum
var. cinnamomeum
var. roseum
ssp. delavayi
var. delavayi
var. peramoenum
ssp. nilagiricum
ssp. zeylanicum
Rhododendron lanigerum
Rhododendron niveum
subsection Argyrophylla
Rhododendron adenopodum
Rhododendron argyrophyllum
ssp. argyrophyllum
ssp. hypoglaucum
ssp. omeinse
ssp. nankingense
Rhododendron coryanum
Rhododendron denudatum
Rhododendron floribundum
Rhododendron formosanum
Rhododendron haofui
Rhododendron hunnewellianum
Rhododendron insigne
Rhododendron longipes
var. chienianum
var. longipes
Rhododendron pingianum
Rhododendron ririei
Rhododendron simiarum
Rhododendron thayerianum
subsection Auriculata
Rhododendron auriculatum
subsection Barbata
Rhododendron argipeplum
Rhododendron barbatum
Rhododendron erosum
Rhododendron exasperatum
Rhododendron succothii
subsection Campanulata
Rhododendron campanulatum
ssp. campanulatum
ssp. aeruginosum
Rhododendron wallichii
subsection Campylocarpa
Rhododendron callimorphum
var. callimorphum
var. myiagrum
Rhododendron campylocarpum
ssp. campylocarpum
ssp. caloxanthum
Rhododendron souliei
Rhododendron wardii
var. puralbum
var. wardii
subsection Falconera
Rhododendron arizelum
Rhododendron basilicum
Rhododendron coriaceum
Rhododendron falconeri
ssp. eximium
ssp. falconeri
Rhododendron galactinum
Rhododendron hodgsonii
Rhododendron preptum
Rhododendron rex
ssp. fictolacteum
var miniforme
ssp. gratum
ssp. rex
Rhododendron rothschildii
Rhododendron semnoides
Rhododendron sinofalconeri
subsection Fortunea
Rhododendron asterochnoum
Rhododendron calophytum
var. calophytum
var. openshawianum
Rhododendron davidii
Rhododendron decorum
ssp. decorum
ssp. diaprepes
Rhododendron fortunei
ssp. discolor
ssp. fortunei
Rhododendron glanduliferum
Rhododendron griffithianum
Rhododendron hemsleyanum
Rhododendron huianum
Rhododendron orbiculare
ssp. cardiobasis
ssp. orbiculare
Rhododendron oreodoxa
var. fargesii
var. oreodoxa
var. shensiense
Rhododendron platypodum
Rhododendron praeteritum
Rhododendron praevernum
Rhododendron serotinum
Rhododendron sutchuenense
Rhododendron vernicosum
subsection Fulgensia
Rhododendron fulgens
subsection Fulva
Rhododendron fulvum
ssp. fulvum
ssp. fulvoides
Rhododendron uvariifolium
var. uvariifolium
var. griseum
subsection Glischra
Rhododendron adenosum
Rhododendron crinigerum
var. cringerum
var. euadenium
Rhododendron glischroides
Rhododendron glischrum
ssp. glischrum
ssp. rude
Rhododendron habrotrichum
Rhododendron recurvoides
Rhododendron spilotum
Rhododendron vesiculiferum
subsection Grandia
Rhododendron balangense
Rhododendron gongshanense
Rhododendron grande
Rhododendron kesangiae
var. kesangiae
var. album
Rhododendron macabeanum
Rhododendron magnificum
Rhododendron montroseanum
Rhododendron praestans
Rhododendron protistum
Rhododendron pudorosum
Rhododendron sidereum
Rhododendron sinogrande
Rhododendron watsonii
subsection Griersoniana
Rhododendron griersonianum
subsection Irrorata
Rhododendron aberconwayi
Rhododendron annae
ssp. annae
ssp. laxiflorum
Rhododendron anthosphaerum
Rhododendron araiophyllum
Rhododendron irroratum
ssp. irroratum
ssp. pogonostylum
Rhododendron kendrickii
Rhododendron ramsdenianum
Rhododendron tanastylum
var. pennivenium
var. tanastylum
Rhododendron wrayi
subsection Lanata
Rhododendron flinckii
Rhododendron lanatoides
Rhododendron lanatum
Rhododendron luciferum
Rhododendron tsariense
subsection Maculifera
Rhododendron anwheiense
Rhododendron longesquamatum
Rhododendron maculiferum
Rhododendron morii
Rhododendron ochraceum
Rhododendron pachysanthum
Rhododendron pachytrichum
Rhododendron pseudochrysanthum
Rhododendron sikangense
var. exquisitum
var. sikangense
Rhododendron strigillosum
subsection Neriiflora
Rhododendron albertsenianum
Rhododendron aperantum
Rhododendron beanianum
Rhododendron catacosmum
Rhododendron chamaethomsonii
var. chamaedoron
var. chamaethauma
var. chamaethomsonii
Rhododendron citriniflorum
var. citriniflorum
var. horaeum
Rhododendron coelicum
Rhododendron dichroanthum
ssp. apodectum
ssp. dichroanthum
ssp. scyphocalyx
ssp. septentrionale
Rhododendron euchroum
Rhododendron eudoxum
var. brunneifolium
var. eudoxum
var. mesopolium
Rhododendron floccigerum
Rhododendron forrestii
ssp. forestii
ssp. papillatum
Rhododendron haematodes
ssp. chaetomallum
ssp. haematodes
Rhododendron mallotum
Rhododendron microgynum
Rhododendron miniatum
Rhododendron neriiflorum
ssp. agetum
ssp. neriiflorum
ssp. phaedropum
Rhododendron parmulatum
Rhododendron piercei
Rhododendron pocophorum
var. hemidartum
var. pocophorum
Rhododendron sanguineum
ssp. didymum
ssp. sanguineum
var. cloiophorum
var. didymoides
var. himertum
var. sanguineum
Rhododendron sperabile
var. sperabile
var. weihsiense
Rhododendron sperabiloides
Rhododendron temenium
var. dealbatum
var. gilvum
var. temenium
subsection Parishia
Rhododendron elliotti
Rhododendron facetum
Rhododendron kyawii
subsection Pontica
Rhododendron aureum
var. aureum
var. hypopytis
Rhododendron brachycarpum
ssp. brachycarpum
ssp. fauriei
Rhododendron catawbiense
Rhododendron caucasicum
Rhododendron degronianum
ssp. degronianum
ssp. heptamerum
var. heptamerum
var. hondoense
var. kyomaruense
ssp. yakushimanum
Rhododendron hyperythrum
Rhododendron macrophyllum
Rhododendron makinoi
Rhododendron maximum
Rhododendron ponticum
Rhododendron smirnowii
Rhododendron ungernii
subsection Selensia
Rhododendron bainbridgeanum
Rhododendron dasycladoides
ssp. jucundum
ssp. setiferum
Rhododendron esetulosum
Rhododendron hirtipes
Rhododendron martinanum
Rhododendron selense
ssp. dasycladum
ssp. selense
subsection Taliensia
Rhododendron adenogynum
Rhododendron aganniphum
var. aganniphum
var. flavorufum
Rhododendron alutaceum
var. alutaceum
var. iodes
var. russotinctum
Rhododendron balfourianum
Rhododendron bathyphyllum
Rhododendron beesianum
Rhododendron bhutanense
Rhododendron bureavii
Rhododendron bureaviodes
Rhododendron clementinae
Rhododendron coeloneuron
Rhododendron dignabile
Rhododendron elegantulum
Rhododendron faberi
Rhododendron inopinum
Rhododendron lacteum
Rhododendron mimetes
var. mimetes
var. simulans
Rhododendron nigroglandulsom
Rhododendron paradoxum
Rhododendron phaeochrysum
var. agglutinatum
var. levistratum
var. phaeochrysum
Rhododendron prattii
Rhododendron principis
Rhododendron pronum
Rhododendron proteoides
Rhododendron przewalskii
ssp. dabanshanense
ssp. przewalskii
Rhododendron purdomii
Rhododendron roxieanum
var. cucullatum
var. oreonastes
var. roxieanum
Rhododendron rufum
Rhododendron sphaeroblatum
var. wumengense
Rhododendron taliense
Rhododendron traillianum
var. dictyotum
var. traillianum
Rhododendron wasonii
var. wenchuanense
Rhododendron wightii
Rhododendron wiltonii
subsection Thomsonia
Rhododendron cerasinum
Rhododendron cyanocarpum
Rhododendron eclecteum
var. bellatulum
Rhododendron faucium
Rhododendron hylaeum
Rhododendron hookeri
Rhododendron meddianum
var. atrokermesinum
var. meddianum
Rhododendron sherriffii
Rhododendron stewartianum
Rhododendron subansiriense
Rhododendron thomsonii
ssp. lopsangianum
ssp. thomsonii
Rhododendron viscidifolium
subsection Venatora
Rhododendron venator
subsection Williamsiana
Rhododendron williamsianum
subgenus Rhododendron
section Pogonanthum
Rhododendron anthopogon
ssp. anthopogon
ssp. hypenanthum
Rhododendron anthopogonoides
Rhododendron cephalanthum
ssp. cephalanthum
ssp. platyphllum
Rhododendron collettianum
Rhododendron fragrans
Rhododendron kongboense
Rhododendron laudandum
var. laudandum
var. temoense
Rhododendron primuliflorum
Rhododendron sargentianum
Rhododendron trichostomum
section Rhododendron
subsection Afghanica
Rhododendron afghanicum
subsection Baileya
Rhododendron baileyi
subsection Boothia
Rhododendron boothii
Rhododendron chrysodoron
Rhododendron dekatanum
Rhododendron leptocarpum
Rhododendron leucaspis
Rhododendron megeratum
Rhododendron sulfureum
subsection Camelliiflora
Rhododendron camelliiflorum
subsection Campylogynum
Rhododendron campylogynum
subsection Caroliniana
Rhododendron minus
var. champmanii
var. minus
subsection Cinnabarinum
Rhododendron cinnabarinum
ssp. cinnabarinum
ssp. tamaense
ssp. xanthocodon
Rhododendron keysii
subsection Edgeworthia
Rhododendron edgeworthii
Rhododendron pendulum
Rhododendron seinghkuense
subsection Fragariflora
Rhododendron fragariiflorum
subsection Genestieriana
Rhododendron genestierianum
subsection Glauca
Rhododendron brachyanthum
ssp. brachyanthum
ssp. hypolepidotum
Rhododendron charitopes
ssp. charitopes
ssp. tsangpoense
Rhododendron glaucophyllum
var. album
var. glaucophyllum
var. tubiforme
Rhododendron luteiflorum
Rhododendron pruniflorum
Rhododendron shweliense
subsection Heliolepida
Rhododendron bracteatum
Rhododendron heliolepis
var. brevistylum
var. fumidum
var. heliolepis
Rhododendron rubiginosum
subsection Lapponica
Rhododendron bulu
Rhododendron capitatum
Rhododendron complexum
Rhododendron cuneatum
Rhododendron dasypetalum
Rhododendron fastigiatum
Rhododendron flavidum
Rhododendron hippophaeoides
var. hippophaeoides
var. occidentale
Rhododendron impeditum
Rhododendron intricatum
Rhododendron lapponicum
Rhododendron nitidulum
var. nitidulum
var. omeiense
Rhododendron nivale
ssp. australe
ssp. boreale
ssp. nivale
Rhododendron orthocladum
var. microleucum
var. orthocladum
Rhododendron polycladum
Rhododendron rupicola
var. chryseum
var. muliense
var. rupicola
Rhododendron russatum
Rhododendron setosum
Rhododendron tapetiforme
Rhododendron telmateium
Rhododendron thymiflolium
Rhododendron tsaii
Rhododendron websterianum
Rhododendron yungningense
subsection Ledum
Rhododendron groenlandicum
Rhododendron hypoleucum
Rhododendron neoglandulosum
Rhododendron subarcticum
Rhododendron subulatum
Rhododendron tolmachevii
Rhododendron tomentosum
subsection Lepidota
Rhododendron cowanianum
Rhododendron lepidotum
Rhododendron lowndesii
subsection Maddenia
Rhododendron burmanicum
Rhododendron carneum
Rhododendron ciliatum
Rhododendron coxianum
Rhododendron dalhousiae
var. dalhousiae
var. rhabdotum
Rhododendron dendricola
Rhododendron excellens
Rhododendron fletcherianum
Rhododendron formosum
var. formosum
var. inaequale
Rhododendron horlickianum
Rhododendron johnstoneanum
Rhododendron leptocladon
Rhododendron levinei
Rhododendron liliiflorum
Rhododendron lindleyi
Rhododendron ludwigianum
Rhododendron lyi
Rhododendron maddenii
ssp. crassum
ssp. maddenii
Rhododendron megacalyx
Rhododendron nuttallii
Rhododendron pachypodum
Rhododendron pseudociliipes
Rhododendron roseatum
Rhododendron scopulorum
Rhododendron taggianum
Rhododendron valentinianum
Rhododendron veitchianum
Rhododendron walongense
subsection Micrantha
Rhododendron micranthum
subsection Monantha
Rhododendron concinnoides
Rhododendron flavantherum
Rhododendron kasoense
Rhododendron monanthum
subsection Moupinensia
Rhododendron dendrocharis
Rhododendron moupinense
Rhododendron petrocharis
subsection Rhododendron
Rhododendron ferrugineum
Rhododendron hirsutum
Rhododendron myrtifolium
subsection Rhodorastra
Rhododendron dauricum
Rhododendron mucronulatum
var. mucronulatum
var. taquetii
Rhododendron sichotense
subsection Saluenensia
Rhododendron calostrotum
ssp. calostrotum
ssp. keleticum
ssp. riparioides
ssp. riparium
Rhododendron saluenense
ssp. chameunum
ssp. saluenense
subsection Scabrifolia
Rhododendron hemitrichotum
Rhododendron mollicomum
Rhododendron pubescens
Rhododendron racemosum
Rhododendron scabrifolium
var. pauciflorum
var. scabrifolium
var. spiciferum
Rhododendron spinuliferum
subsection Tephropepia
Rhododendron auritum
Rhododendron hanceanum
Rhododendron longistylum
Rhododendron tephropeplum
Rhododendron xanthostephanum
subsection Trichoclada
Rhododendron caesium
Rhododendron lepidostylum
Rhododendron mekongense
var. mekongense
var. rubrolineatum
Rhododendron trichocladum
Rhododendron viridescens
subsection Triflora
Rhododendron ambiguum
Rhododendron augustinii
ssp. augustinii
ssp. chasmanthum
ssp. hardyi
ssp. rubrum
Rhododendron concinnum
Rhododendron davidsonianum
Rhododendron keiskei
var. keiski
var. ozawae
Rhododendron lutescens
Rhododendron oreotrephes
Rhododendron polylepis
Rhododendron rigidum
Rhododendron seariane
Rhododendron siderophyllum
Rhododendron tatsienense
Rhododendron trichanthum
Rhododendron triflorum
var. bauhiniiflorum
var. triflorum
Rhododendron yunnanense
Rhododendron zaleucum
var. zaleucum
var. flaviflorum
subsection Uniflora
Rhododendron imperator
Rhododendron ludlowii
Rhododendron pemakoense
Rhododendron pumilum
Rhododendron uniflorum
subsection Virgata
Rhododendron virgatum
ssp. virgatum
ssp. oleifolium
section Vireya
subsection Albovireya
Rhododendron aequabile
Rhododendron album
Rhododendron arenicolum
Rhododendron cernuum
Rhododendron comptum
var. trichodes
Rhododendron correoides
Rhododendron giulianetti
Rhododendron lagunculicarpum
Rhododendron lampongum
Rhododendron proliferum
Rhododendron pudorinum
Rhododendron versteegii
Rhododendron yelliotii
Rhododendron zollingeri
subsection Malayovireya
Rhododendron acuminatum
Rhododendron apoanum
Rhododendron durionifolium
ssp. sabahense
Rhododendron fallacinum
Rhododendron fortunans
Rhododendron himantodes
var. lavandulifolium
Rhododendron lamrialianum
var. gunsalamianum
Rhododendron lineare
Rhododendron malayanum
var. axillare
var. axillare latifolium
var. axillare ovatum
var. infrapilosum
var. pilosifilum
var. pubens
Rhododendron micromalayanum
Rhododendron nortoniae
Rhododendron obscurum
Rhododendron variolosum
var. andersonii
Rhododendron vinicolor
subsection Phaeovireya
Rhododendron asperrimum
Rhododendron asperum
Rhododendron beyerinckianum
Rhododendron bryophilum
Rhododendron bullifolium
Rhododendron caliginis
Rhododendron cyatheicolum
Rhododendron delicatulum
var. lanceolatoides
Rhododendron dianthosmum
Rhododendron dielsianum
var. stylotrichum
Rhododendron extrorsum
Rhododendron eymae
Rhododendron gardenia
Rhododendron gilliardii
Rhododendron haematophthalmum
Rhododendron hellwigii
Rhododendron hooglandii
Rhododendron hyacinthosmum
Rhododendron kerowagiense
Rhododendron konori
var. phaeopeplum
Rhododendron leptanthum
var. warianum
Rhododendron melantherum
Rhododendron neriifolium
Rhododendron opulentum
Rhododendron phaeochitum
Rhododendron phaeochristum
Rhododendron phaeops
Rhododendron prainianum
Rhododendron psilanthum
Rhododendron rappardii
Rhododendron rarum
Rhododendron revolutum
Rhododendron rhodochroum
Rhododendron rubellum
Rhododendron schoddei
Rhododendron solitarium
Rhododendron spondylophyllum
Rhododendron stelligerum
Rhododendron stolleanum
Rhododendron superbum
Rhododendron thaumasianthum
Rhododendron truncicolum
Rhododendron tuberculiferum
subsection Pseudovireya
Rhododendron adinophyllum
Rhododendron asperulum
Rhododendron borneense
ssp. angustissimum
ssp. villosum
Rhododendron buxoides
Rhododendron capellae
Rhododendron ciliilobum
Rhododendron cuneifolium
var. microcarpum
Rhododendron cyrtophyllum
Rhododendron datiandingense
Rhododendron densifolium
Rhododendron emarginatum
var. eriocarpum
Rhododendron ericoides
Rhododendron erosipetalum
Rhododendron gaultheriifolium
var. expositum
Rhododendron hameliiflorum
Rhododendron insculptum
Rhododendron kawakamii
Rhododendron leiboense
Rhododendron lindaueanum
var. bantaengense
Rhododendron maguanense
Rhododendron meliphagidum
Rhododendron nanophyton
var. petrophilum
Rhododendron nummatum
Rhododendron oreites
var. chlorops
Rhododendron perakense
Rhododendron pulleanum
var. maiusculum
Rhododendron quadrasianum
var. davaoense
var. intermedium
var. malindangense
var. marivelesense
var. rosmarinifolium
var. selebicum
Rhododendron retusum
var. epilosum
var. trichostylum
Rhododendron rupivalleculatum
Rhododendron rushforthii
Rhododendron santapaui
Rhododendron saruwagedicum
Rhododendron schizostigma
Rhododendron scortechinii
Rhododendron seimundii
Rhododendron sororium
Rhododendron spathulatum
Rhododendron taxoides
Rhododendron vaccinioides
Rhododendron vanderbiltianum
Rhododendron vinkii
subsection Siphonovireya
Rhododendron agathodaemonis
Rhododendron cinchoniflorum
Rhododendron gideonii
Rhododendron habbemae
Rhododendron herzogii
Rhododendron incommodum
Rhododendron inundatum
Rhododendron protandrum
Rhododendron reevei
subsection Solenovireya
Rhododendron alborugosum
Rhododendron amabile
Rhododendron archboldianum
Rhododendron armitii
Rhododendron brachypodarium
Rhododendron carrii
Rhododendron carringtoniae
Rhododendron carstensense
Rhododendron chamaepitys
Rhododendron cinerascens
Rhododendron cruttwellii
Rhododendron edanoi
ssp. pneumonanthum
Rhododendron goodenoughii
Rhododendron hartleyi
Rhododendron jasminiflorum
var. copelandii
var. heusseri
var. oblongifolium
var. punctatum
Rhododendron lambianum
Rhododendron loranthiflorum
ssp. lakekamuensis
Rhododendron macrosiphon
Rhododendron maius
Rhododendron mendumiae
Rhododendron mogeanum
Rhododendron multinervium
Rhododendron natalicium
Rhododendron niveoflorum
Rhododendron oliganthum
Rhododendron orbiculatum
Rhododendron oreadum
Rhododendron pleianthum
Rhododendron pseudotricanthum
Rhododendron pubitubum
Rhododendron radians
var. minahasae
Rhododendron retrorsipilum
Rhododendron rhodoleucum
Rhododendron rhodosalpinx
Rhododendron roseiflorum
Rhododendron ruttenii
Rhododendron searleanum
Rhododendron stapfianum
Rhododendron suaveolens
var. roseum
Rhododendron subpacificum
Rhododendron syringoideum
Rhododendron tuba
Rhododendron
subsection Vireya
Rhododendron abietifolium
Rhododendron acrophilum
Rhododendron alternans
Rhododendron alticolum
Rhododendron anagalliflorum
Rhododendron angulatum
Rhododendron apiense
Rhododendron arfakianum
Rhododendron atropurpureum
Rhododendron aurigeranum
ssp. hirsutum
Rhododendron baconii
Rhododendron baenitzianum
Rhododendron bagobonum
Rhododendron banghamiorum
Rhododendron beccarii
Rhododendron blackii
Rhododendron bloembergenii
Rhododendron brachygynum
Rhododendron brassii
Rhododendron brevipes
Rhododendron burttii
Rhododendron buruense
Rhododendron buxifolium
Rhododendron caespitosum
Rhododendron calosanthes
Rhododendron celebicum
Rhododendron chevalieri
Rhododendron christi
Rhododendron christianae
Rhododendron citrinum
var. discoloratum
Rhododendron coelorum
Rhododendron commonae
Rhododendron commutatum
Rhododendron comparabile
Rhododendron cornu-bovis
Rhododendron crassifolium
Rhododendron culminicolum
var. angiense
var. nubicola
Rhododendron curviflorum
Rhododendron cuspidellum
Rhododendron detznerianum
Rhododendron disterigmoides
ssp. astromontium
Rhododendron englerianum
Rhododendron exuberans
Rhododendron flavoviride
Rhododendron frey-wysslingii
Rhododendron glabriflorum
Rhododendron gracilentum
Rhododendron hatamense
Rhododendron helodes
Rhododendron hirtolepidotum
Rhododendron impositum
Rhododendron impressopunctatum
Rhododendron inconspicuum
Rhododendron intranervatum
Rhododendron javanicum
ssp. brookeanum
ssp. cockburnii
ssp. palawanense
ssp. schadenbergii
var. teysmannii
Rhododendron kemulense
Rhododendron kochii
Rhododendron laetum
Rhododendron lamii
Rhododendron lanceolatum
Rhododendron leptobrachion
Rhododendron leptomorphum
Rhododendron leucogigas
Rhododendron leytense
var. loheri
Rhododendron loboense
Rhododendron lochiae
Rhododendron loerzingii
Rhododendron lompohense
Rhododendron longiflorum
var. bancanum
var. longipetalum
var. subcordatum
Rhododendron lowii
Rhododendron luraluense
Rhododendron luteosquamatum
Rhododendron macgregoriae
var. glabrifilum
var. mayrii
Rhododendron madulidii
Rhododendron maxwellii
Rhododendron meijeri
Rhododendron microphyllum
Rhododendron mindanaense
Rhododendron mollianum
Rhododendron monkoboense
Rhododendron multicolor
Rhododendron muscicola
Rhododendron myrsinites
Rhododendron neobritannicum
Rhododendron nervulosum
Rhododendron nieuwenhuisii
Rhododendron oxycoccoides
Rhododendron pachycarpon
Rhododendron pachystigma
Rhododendron papuanum
Rhododendron parvulum
Rhododendron pauciflorum
var. calocodon
Rhododendron perplexum
Rhododendron polyanthemum
Rhododendron poremense
Rhododendron porphyranthes
Rhododendron praetervisum
Rhododendron psammogenes
Rhododendron pseudobuxifolium
Rhododendron pseudomurudense
Rhododendron pubigermen
Rhododendron purpureiflorum
Rhododendron pusillum
Rhododendron pyrrhophorum
Rhododendron rarilepidotum
var. ootrichum
Rhododendron renschianum
Rhododendron retivenium
Rhododendron reynosoi
Rhododendron rhodopus
Rhododendron rhodostomum
Rhododendron ripleyi
var. basitrichum
var. cryptogonium
Rhododendron robinsonii
Rhododendron rosendahlii
Rhododendron rousei
Rhododendron rubineiflorum
Rhododendron rubrobracteatum
Rhododendron rugosum
var. kinabaluense
Rhododendron salicifolium
Rhododendron sarcodes
Rhododendron saxifragoides
Rhododendron sayeri
Rhododendron scabridibracteum
Rhododendron scarlatinum
Rhododendron schlechteri
Rhododendron seranicum
Rhododendron sessilifolium
Rhododendron simulans
Rhododendron stenophyllum
ssp. angustifolium
Rhododendron stevensianum
Rhododendron stresemanii
Rhododendron subcrenulatum
Rhododendron subuliferum
Rhododendron subulosum
Rhododendron sumatranum
Rhododendron takeuchii
Rhododendron taxifolium
Rhododendron toxopei
Rhododendron triumphans
Rhododendron tuhanensis
Rhododendron ultimum
Rhododendron vanvuurenii
Rhododendron verticillatum
var. velutinum
Rhododendron vidalii
ssp. brachystemon
Rhododendron villosulum
Rhododendron viriosum
Rhododendron vitis-idaea
Rhododendron wentianum
Rhododendron whiteheadii
Rhododendron wilkiei
Rhododendron williamsii
Rhododendron womersleyi
Rhododendron wrightianum
var. cyclopense
var. insulare
Rhododendron xanthopetalum
Rhododendron xenium
Rhododendron yongii
Rhododendron zoelleri
subgenus Therorhodion
Rhododendron camtschaticum
ssp. camtschaticum
ssp. glandulosum
Rhododendron redowskianun

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