Rhododendron L.
  • Sp. Pl. 1: 392. 1753. (1 May 1753)
  • Azalea [Greek rhodon, rose and dendron, tree]

Cite taxon page as 'WFO (2021): Rhododendron L. Published on the Internet;http://www.worldfloraonline.org/taxon/wfo-4000033027. Accessed on: 27 Oct 2021'

General Information

Shrubs or trees, terrestrial or epiphytic, with various hairs, and/or with peltate scales or glabrous, indumentum sometimes detersile (the hairs tangled and coming away as a layer). Leaves evergreen, deciduous or semideciduous, alternate, sometimes clustered at stem apex; margin entire, very rarely crenulate, abaxial indumentum sometimes with a pellicle (a thin skinlike layer on the surface). Inflorescence a raceme or corymb, mostly terminal, sometimes lateral, few- to many-flowered, sometimes reduced to a single flower. Calyx persistent, 5–8-lobed, sometimes reduced to a rim, lobes minute and triangular to large and conspicuous. Corolla funnelform, campanulate, tubular, rotate or hypocrateriform, regular or slightly zygomorphic, 5(–8)-lobed, lobes imbricate in bud. Stamens 5–10(–27), inserted at base of corolla, usually declinate; filaments linear to filiform, glabrous or pilose towards base; anthers without appendages, opening by terminal or oblique pores. Disk usually thick, 5–10(–14)-lobed. Ovary 5(–18)-locular, with hairs and/or scales, rarely glabrous. Style straight or declinate to deflexed, persistent; stigma capitate-discoid, crenate to lobed. Capsule cylindrical, coniform, or ovoid, sometimes curved, dehiscent from top, septicidal; valves thick or thin, straight or twisted. Seeds very numerous, minute, fusiform, always winged, or both ends with appendages or thread-like tails.

  • Provided by: [E].Flora Of CHina @ efloras.org
    • Source: [
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    6. Rhododendron L.

    Por J.L. Luteyn.

    Arbustos o árboles; indumento de pelos unicelulares, multicelulares, glandulares y eglandulares, y escamas. Hojas alternas a seudoverticiladas, perennes o deciduas, pecioladas o subsésiles, aplanadas a longitudinalmente rizadas, coriáceas o cartáceas, pinnatinervias, los márgenes enteros o rara vez ciliado-serrulados. Inflorescencias terminales o axilares, peruladas, umbeliformes o corimbosas, a veces solitarias; pedicelos continuos con el cáliz; brácteas y bractéolas deciduas. Flores 5-meras, sin aroma, la, estivación imbricada; lobos del cáliz libres, generalmente 5(-10); corola simpétala, (4-)5-8(-10)-lobada, rotácea a campanulada, o infundibuliforme, a veces tubular, generalmente zigomorfa, decidua; estambres 5-10(-20); filamentos desiguales, pubescentes o glabros; anteras sin apéndices, el tejido de desintegración ausente, dehiscentes por poros terminales; polen con hilos de viscina; ovario súpero, 5(-20)-locular. Frutos secos en cápsulas septicidas, generalmente ovoides a oblongas; semillas numerosas, diminutas, aladas a fusiformes. Aprox. 900 spp. Zonas templadas, la mayoría en Asia y Norteamérica. 1 especie cultivada en zonas Neotropicales.

    Bibliografía: Clemants, S.E. Fl. Neotrop. 66: 131-132 (1995).

    La única especie en Mesoamérica es Rhododendron simsii .

  • Provided by: [C].Flora Mesoamericana
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    Rhododendron simsii Planch., Fl. Serres Jard. Eur. 9: 78. 1854.

    Arbustos 1 m de alto, con todas las partes vegetativas cubiertas con tricomas aciculares escamiformes y tricomas cortos frecuentemente piloso-glandulares. Hojas alternas o pseudoverticiladas, membranáceas, elíptico-lanceoladas a oblanceoladas, 2.5–4.5 cm de largo y 1–1.5 cm de ancho, ápice agudo u obtuso y mucronado, base aguda, margen ciliado; pecíolos 3–5 mm de largo. Inflorescencias corimbos o racimos terminales, pocas flores; cáliz 8–10 mm de largo, irregularmente lobado o hendido, cubierto con tricomas glandulares; corola asimétrica, hipocrateriforme, ampliamente patente distalmente, ca 4.5–5 cm de largo y de ancho, glabra, blanca con puntos rojo-morados; estambres 5, más o menos desiguales, inclinados, anteras ca 2 mm de largo, sin espolones; ovario densamente fasciculado hirsutos. Cápsula septicida no vista.

    Cultivada, Matagalpa; 1270 m; fl dic; Stevens 22576. Un género con casi 900 especies distribuidas en las regiones templadas mayormente en Asia y Norteamérica; sólo esta especie es cultivada en América tropical.

    S.E. Clemants. Rhododendron Linnaeus. Ericaceae Part II. The superior-ovaried genera. Fl. Neotrop. 66: 131–132. 1995.

  • Provided by: [F].Flora de Nicaragua
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    Subshrubs, shrubs, or trees, (rhizomatous or not). Stems erect (and/or creeping, prostrate in R. groenlandicum, R. lapponicum, R. tomentosum); twigs hairy or glabrous, (older twigs without peglike projections). Leaves persistent or deciduous, alternate; petiole present; blade coriaceous to membranous, (base cuneate, rounded, or obtuse), margins entire, (sometimes ciliate, plane to revolute, abaxial surface 1/3+ visible except sometimes in bud, surfaces hairy and/or scaled, midvein hairy or not, adaxial surface sometimes impressed; venation usually brochidodromous). ( Winter buds usually large, with imbricate scales; floral buds usually larger than vegetative buds.) Inflorescences terminal (axillary in R. albiflorum, short, corymbiform or rounded racemes (fasciculate racemes in R. canadense, R. lapponicum; fasciculate in R. albiflorum), 3-35-flowered (1-2-flowered in R. albiflorum); perulae brownish, scalelike, dry. ( Pedicels horizontal to erect (recurved); bracteoles 2, brownish, scalelike, basal.) Flowers bisexual, weakly bilaterally symmetric (radially symmetric in R. columbianum, R. groenlandicum, R. tomentosum, scented or not); sepals 5[-9], slightly connate; petals 5[-9], strongly to only slightly connate (sometimes nearly distinct), corolla deciduous, rotate to campanulate or funnelform; stamens 5-12[-20], included to long-exserted; (filaments usually unequal, usually unicellular-hairy, glabrous in R. vaseyi, glabrous or proximally unicellular-hairy in R. groenlandicum, R. lapponicum); anthers without awns, dehiscent by terminal pores; ovary 5[-18]-locular; style inserted in slight depression at ovary apex or smoothly intergrading, (usually curved, long, slender); stigma capitate. Fruits capsular, elongate, usually ovoid to cylindric, dehiscence usually basipetally septicidal (acropetally septicidal in R. columbianum, R. groenlandicum, R. tomentosum). Seeds (10-)100+, flattened-ellipsoidal to fusiform, often tailed, ± winged; testa smooth. x = 13.

  • Provided by: [D].Flora of North America @ efloras.org
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    • 4
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    "Cal 5-lobed, much shorter than the cor; cor campanulate to funnelform, conspicuous, regularly or commonly irregularly 5-lobed; stamens mostly 5 or 10, with elongate filaments and short anthers with 2 terminal pores; ovary superior, 5-locular; style elongate; capsule septicidal; shrubs or trees with alternate, deciduous or evergreen lvs and showy fls in terminal racemes or umbel-like clusters from scaly buds. Our spp. 2n=26, except as noted. (Azalea) 850, mainly N. Hemisphere."

  • Provided by: [G].New York Botanical Garden
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    SELECTED REFERENCES Chamberlain, D. F. 1982. A revision of Rhododendron II. Subgenus Hymenanthes. Notes Roy. Bot. Gard. Edinburgh 39: 209-486. Chamberlain, D. F. et al. 1996. The Genus Rhododendron: Its Classification and Synonymy. Oxford. Chamberlain, D. F. and S. J. Rae. 1990. A revision of Rhododendron IV. Subgenus Tsutsusi. Edinburgh J. Bot. 47: 89-200. Cullen, J. 1980. A revision of Rhododendron. 1. Subgenus Rhododendron sections Rhododendron and Pogonanthum. Notes Roy. Bot. Gard. Edinburgh 39: 1-207. Goetsch, L., A. J. Eckert, and B. D. Hall. 2005. The molecular systematics of Rhododendron (Ericaceae): A phylogeny based upon RPB2 gene sequences. Syst. Bot. 30: 616-626. Harmaja, H. 1991. Taxonomic notes on Rhododendron subsection Ledum (Ledum, Ericaceae), with a key to its species. Ann. Bot. Fenn. 28: 171-173. Judd, W. S. and K. A. Kron. 1995. A revision of Rhododendron VI. Subgenus Pentanthera (sections Sciadorhodion, Rhodora, and Viscidula). Edinburgh J. Bot. 52: 1-54. Kron, K. A. 1993. A revision of Rhododendron section Pentanthera. Edinburgh J. Bot. 50: 249-364. Kurashige, Y. et al. 2001. Sectional relationships in the genus Rhododendron (Ericaceae): Evidence from matK and trnK intron sequences. Pl. Syst. Evol. 228: 1-14. Philipson, W. R. and M. N. Philipson. 1986. A revision of Rhododendron III. Subgenera Azaleastrum, Mumeazalea, Candidastrum and Therorhodion. Notes Roy. Bot. Gard. Edinburgh 44: 1-23. Sleumer, H. 1980. A system of the genus Rhododendron L. In: J. L. Luteyn and M. E. O’Brien, eds. 1980. Contributions toward a Classification of Rhododendron: Proceedings, International Rhododendron Conference...May 15-17, 1978.... Bronx. Pp. 1-18.

  • Provided by: [D].Flora of North America @ efloras.org
    • Source: [
    • 4
    • ]. 

    Included Species

    Other Local Names

    Azalea [Greek rhodon, rose and dendron, tree]

     Information From

    World Flora Online Data. 2017.
    • A CC0 1.0 Universal (CC0 1.0).
    MBG Floras Images
    Flora images. Missouri Botanical Garden. Accessed on Jun. 2018.
    • B Missouri Botanical Garden
    Flora Mesoamericana
    Gerrit Davidse, Mario Sousa Sánchez, A. O. Chater, Universidad Nacional Autónoma de México. Instituto de Biología, Missouri Botanical Garden, Natural History Museum (London, England) UNAM, 1994
    • C Missouri Botanical Garden
    Flora of North America @ efloras.org
    'Flora of North America @ eFloras (2008). Published on the Internet http://www.efloras.org/flora_page.aspx?flora_id=1 [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
    • D Flora of North America Association
    Flora Of CHina @ efloras.org
    'Flora of China @ eFloras (2008). Published on the Internet http://www.efloras.org/flora_page.aspx?flora_id=2 [accessed August 2016]' Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
    • E Missouri Botanical Garden
    Flora de Nicaragua
    WD Stevens, CU Ulloa, A Pool and OM Montiel. Missouri Botanical Garden Press, 2001
    • F Missouri Botanical Garden
    New York Botanical Garden
    Descriptions of plants should be attributed to the full citation for each individual article, chapter or book that is the source for each record, which should include the authors of original publication.
    • G Content licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
    World Flora Online consortium
    World Flora Online Data. 2018.
    • H CC0 1.0 Universal (CC0 1.0).