rhodynThese pages are the result of information the author picked up over 45 years at American Rhododendron Society meetings & conventions, in courses at Longwood Gardens and Oregon State University, and in the numerous books. Since it was created in 1996, the goal of this site is to share this information with those who share a love for the genus Rhododendron. For compatibility information or to contact the webmaster click HERE. This website is now available in 13 languages.

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Genus Rhododendron

The Genus Rhododendron
Azaleas, Where They Fit In

Directory of Pages on This Website
Index of Rhododendron & Azalea Topics

rhodynRhododendrons are shrubs of the genus Rhododendron, which is in the heath family (family Ericaceae) which includes heathers, Kalmia (mountain laurels), blueberries and cranberries. Since almost all of these plants require acidic soil, they are often referred to as the family of acid-loving plants. Rhododendrons are found in the wild, chiefly in mountainous areas of the arctic and north temperate zones. They typically have large, shiny, leathery evergreen leaves and clusters of large pink, white, or purplish flowers. North American species include the great laurel, or rose bay (R. maximum), West Virginia's state flower; and the Western rhododendron (R. macrophyllum), Washington's state flower. Azaleas are in the same genus. Most cultivated rhododendrons are hybrids that are propagated from cuttings or tissue culture. Rhododendrons are referred to as the King of Shrubs since they are regarded by many as the best flowering evergreen plants for the temperate landscape.

Rhododendrons are shrubs for all seasons. In winter some stand out with large evergreen leaves. In spring the flowers are showy; throughout the summer and fall the leaves add a pleasing, deep green color to the garden. Some deciduous azaleas add bright fall color before the leaves drop. The spectacular spring flowers of azaleas and rhododendrons make them among the most popular garden shrubs.

Rhododendrons are divided into 6 groups:

When botanists categorize rhododendrons and azaleas they refer to scales. These "scales" are about the diameter of a human hair and are easily visible with a hand lens. The term lepidote is used to describe the rhododendrons with scales on their leaves and stems, while the term elepidote is used to describe the rhododendrons without scales. All azaleas are also elepidotes. About one third of all rhododendron species are in a group of tropical rhododendrons called Vireyas. Vireyas are classified with the other lepidotes in the subgenus Rhododendron.

Also see details and pictures of the 27 species of Rhododendrons and Azaleas that are native to North America.

Genus Rhododendron

Rhododendrons belong to the family Ericaceae. There are very few rhododendron fossils. The ericaceous plants (recognizable by their fossilized pollen grains that are arranged in groups of four) appeared first in the Maastrichtian Stage about 68 million years ago. The Maastrichtian is the last stage of the Cretaceous Period and immediately precedes the extinction of dinosaurs. The earliest rhododendron fossils are leaf imprints in rocks of early Tertiary age (about 50 million years old) from Alaska. Other fossils are known from the Tertiary and Pleistocene deposits of North America. These records indicate that rhododendrons have been in existence for at least 50 million years. They could have been in existence before that time, but not before 68 million years ago when the Ericaceae first appeared. This is of interest because it indicates that rhododendrons probably did not originate in the region of mountainous regions of SE Asia or in the high-island archipelago stretching between mainland Asia and Australia - the islands of Java, Sumatra, Borneo, New Guinea, and the Philippines (where they are now most abundant and most diverse) because these regions did not exist 50 million years ago.

E. Irving and R. Hebda of Victoria, Canada, have studied fossils and the genetics of rhododendrons and inferred the possible way they became distributed the way they are today. The essence of their thesis is that, following a period of mild climate, the fairly limited number of rhododendron speciess were widely and more-or-less continuously distributed across North America and Eurasia. When the Indian subcontinent collided with the Eurasian continent, this raised the Tibet-Himalayan region and formed the extreme relief of the Himalayan Mountains. The not only changed the topography, but also the climate. The range of rhododendron speices became much reduced as a result of global climatic deterioration. This deterioration began about 25 million years ago, was clearly marked by about 15 million years ago, and became extreme with the onset of the current glacial period about 3 million years ago. Small populations of the subgenera Hymenanthes and Rhododendron (but not azaleas) situated on the edges of their main range were able to enter and retain a foothold in the newly developing region of extreme relief on the southeastern fringe of the Tibet-Himalayan region. There they we divided into constantly change pockes to compatible climate. These pockets would join and seperate as the climate went through dramatic changes. The constantly increasing numbers of species proliferated, and it was from there that the vireyas spread into the mountains of the high-island archipelago stretching between mainland Asia and Australia. By taking advantage of special newly developing conditions, these populations, while small originally, have become now the most numerous and diverse. The place of origin of rhododendrons is not known, but it was not the region of extreme relief on the southeastern fringe of the Tibet-Himalayan region where they are nowadays most diverse and abundant. See Why Rhododendrons grow where they do and how they got there.

The azaleas are not in the mountains of SE Asia although they live close by in terrain of about one-half or one-third the altitude. Presumably, because of their genetic make-up and historical circumstances, they were unable to take advantage of the dynamic environment of that region. In this respect, the paleogeographical evolution of azaleas appears therefore to have been very different from that of other rhododendrons.

Also see:

History of the Genus Rhododendron

History of Discovery and Cultivation of Rhododendrons and Azaleas

History of the First 50 Years of Hybridization of Rhododendrons and Azaleas

rhodynAzaleas, Where They Fit In

Azaleas are shrubs of the genus Rhododendron and members of the heath family. There are 8 divisions of the genus Rhododendron. Azaleas comprise two of those divisions. Technically classified as rhododendrons, azaleas are generally more floriferous but have less impressive foliage. Typically non-azalea rhododendrons are evergreen and have flowers that are in trusses (a truss is a flower-like structure composed of many flowers). Typically an azalea is either evergreen with flowers singly rather than in a truss or are deciduous and may have flowers singly or in a ball-shaped truss.

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 Rhododendron could not be maintained as distinct genera. In 1834, George Don subdivided the genus Rhododendron into 8 sections. Azaleas comprise two of these sections, Subgenus Pentanthera typified by deciduous Rhododendron nudiflorum and Subgenus Tsutsusi typified by evergreen Rhododendron tsutsusi.

If flowers grow from terminal buds, new leaves and shoots grow from lateral buds and leaves are deciduous, then the rhododendron is an azalea in the Pentanthera subgenus.

If flowers and leaves grow from the same terminal buds, and the flowers have 5 to 10 stamens, then the rhododendron is an azalea in the Tsutsusi subgenus.

In 2004, Goetsch, et. al. rearranged the 8 former subgenera into 5 subgenera. Today, Azaleas are grouped into the Pentanthera Subgenus and Azaleastrum Subgenus.

Most grow in damp acid soils of hills and mountains, and are native to North America and Asia. Native American azaleas include the flame azalea (R. calendulaceum) and the fragrant white azalea (R. viscosum), also called swamp honeysuckle. Many of the brilliantly flowered garden varieties are from China and Japan. Some have deciduous leaves and are usually very hardy, while others are evergreen and frequently less hardy. The deciduous varieties are usually hard to propagate, but much progress had been made in this area. Evergreen varieties are usually easy to propagate. Many hybrid and species azaleas are in the commercial trade. They typically bloom early in the season and are popular for the color they add to the landscape.

One term that is used in describing many azaleas is hose-in-hose. This term is meant to describe what looks like a flower inside a flower. This actually is a flower with a large calyx. The sepals of the calyx are shaped like the petals of the corolla. It appears as two similar corollas, one inside the other and rotated so that all the petals are visible.

Another term that is more common with azaleas is double. A double flower looks like the interior is filled with petals. This is because the stamens grow into petal-like structures. The pistol may also be transformed into a petal-like structure or may be absent.

Another term is semi-double. In this case the stamens are partially transformed into petal-like structures. Occasionally extra petals are present and all stamens are present also.

Another version is hose-in-hose double. A perfect example of this is Gable's Rosebud azalea. The name is descriptive of the flowers appearance.

Also see details and photos of the 16 species of Azaleas that are native to North America.

Rhododendron and Azalea Links

If you have a link to this site and I do not have a link to your site, please email me so I can link to you.

I want to extend a big Thank You to the following sites for their links to this site and I recommend others visit the sites of these enthusiastic Rhododendron and Azalea gardeners:

The following links also have valuable information for Rhododendron and Azalea gardeners.

Also a big Thank You to the following sites which gave nice reviews of this site and they may be helpful in finding links to other sites:

  • About Landscaping - "an excellent information source on these plants, suggests a few shade trees compatible with azaleas and rhododendrons, among them being the red oak (Quercus rubra)."
  • Absolute Astronomy - "Extensive information on rhododendron species; the history of their discovery, botanical details, toxicity, classification, cultural conditions, care for common problems, and suggestions for companion plants by Steve Henning."
  • American Rhododendron Society - "... mastered the development of internet websites and used them effectively to inform and instruct the public about rhododendrons. Henning's rhododendron and azalea pages was one of the earliest sources of on-line information."
  • American Rhododendron Society - District One - "All about Rhododendrons and Azaleas"
  • answers.com - "Extensive information on rhododendron species: the history of their discovery, botanical details, toxicity, classifications, cultural conditions, care for common problems, and suggestions for companion plants by Steve Henning."
  • Archaeolink.com - "You will find description of various types of rhododendron and learn how to grow them, plus much more.  A lot of click-to-read articles and other resources. - illustrated."
  • ARS, District 1 (BC, Canada) - "All about Rhododendrons and Azaleas."
  • Azalea Chapter, ARS - "Probably the best source for disease and pests may be found on the Culture and Problem pages of Steve Henning's excellent website."
  • Azalea Factbites - "a general treatise on a wide-ranging variety of topics, with one of the most-detailed sections on problems that may arise with rhododendrons."
  • Azalea Society of America - "Excellent comprehensive information about rhododendrons, azaleas and companion plants; good source of gardening books; many azalea links."
  • B & T Seeds - "An astonishing resource, probably the best place to start looking for Rhododendron and Azalea information."
  • Danish Chapter of the ARS - "Lots of good info by S. Henning."
  • Encyclopedia of Life - "Extensive information on rhododendron species: the history of their discovery, botanical details, toxicity, classification, cultural conditions, care for common problems, and suggestions for companion plants by Steve Henning."
  • Finnish Rhododendron Society - "hyvät sivut alppiruusuista ja atsaleoista"
  • Flowering Shrub Farm - "Henning's rhododendron and azalea pages feature descriptions, cultural, and trouble shooting pages as well as companion plants."
  • Gardening Launch Pad -"Lots of good info, by S. Henning."
  • Geometry - Rhododendron Gardening - "These pages are the result of information picked up over 35 years at American Rhododendron Society meetings, and in the numerous books available in the Rhododendron and Azalea Bookstore . The goal of this site is to share this information with those who share a love for the genus Rhododendron. All proceeds from the Rhododendron and Azalea Bookstore are contributed to the ARS Research Fund and the Rhododendron Species Foundation. ... "
  • Rhododendra - "Good Stuff From Across the Web (Steve Henning's page)."
  • Hort.net - "Ever have questions about Rhododendrons? If so, a visit to this site might be well worth the effort. The author has put a lot of work into the creation of a well-rounded document discussing various species, cultural requirements, companion plants, troubleshooting, and of course, links to other resources."
  • HubPages - "Henning's rhododendron and azalea page: how to grow them and trouble shooting problems."
  • I Can Garden - "These pages are the result of information picked up over 35 years at American Rhododendron Society meetings, and in the numerous books made available in the Rhododendron and Azalea Bookstore. "
  • IdeasForGardens: Gardeners with websites - "Steve Henning. The goal of this site is to share this information with those who share a love for the genus Rhododendron. "
  • John & Jacq's Garden - "... almost everything you need to know about these spectacular shrubs."
  • K. G. Karlsson - "Fantaster"
  • Landscaping - "an excellent information source on these plants, suggests a few shade trees compatible with azaleas and rhododendrons, among them being the red oak (Quercus rubra)."
  • Mary's Plant Farm - "a great site about rhododendrons and azaleas"
  • Mashpedia - "Extensive information on rhododendron species: the history of their discovery, botanical details, toxicity, classification, cultural conditions, care for common problems, and suggestions for companion plants by Steve Henning."
  • Mason-Dixon Chapter of ARS - "Henning's Rhododendron & Azaleas Pages is a general treatise on a wide-ranging variety of topics, with one of the most-detailed sections on problems that may arise with rhododendrons."
  • Medbib - "Extensive information on rhododendron species: the history of their discovery, botanical details, toxicity, classification, cultural conditions, care for common problems, and suggestions for companion plants by Steve Henning."
  • Mount Arrowsmith Rhododendron Society- "All about rhodos and azaleas by the Hennings: great place for general information on these plants for the general or novice gardener."
  • Paghat's Garden - "He has many wonderful rhododendron articles & links at Stephen M. Henning's Rhododendron Pages, & he has the best rhododendron library."
  • Rhododendron Garden in Archipelago Forest - "Stephen Henning on tehnyt erittäin hyvät ja kattavat ohjeet rhodojen kasvatuksesta. Hänen rhodo- ja atsaleasivunsa Rhododendron & Azaleas ovat myös todella käymisen arvoiset. Suosittelen!"
  • RHODODENDRON LINKKEJÄ - "How to grow Rhododendron and Azaleas  / Stephen M. Henning Stephen Henning on tehnyt erittäin hyvät ja kattavat ohjeet rhodojen kasvatuksesta. Hänen rhodo- ja atsaleasivunsa Rhododendron & Azaleas ovat myös todella käymisen arvoiset. Suosittelen!" by K Theqvist.
  • Rhododendron Society of Canada - "Henning's Photos & Advice: Advice - How to Grow Rhodos & Azaleas and Advice - Problems & Solutions"
  • Rhododendron Species Foundation - "Steve Henning's site with many links and his own Rhododendron and Azalea Bookstore."
  • Richard Francis Plant Pages - "Steve Henning's Rhododendron pages are a generous wealth of reliable information on the genus, a book in themselves, including the best collection of rhododendron links I could imagine."
  • SJG Bloom- "a very detailed information on explorers, taxonomy and classification of rhododendrons"
  • Valley Forge Chapter - ARS - "The leading, non-commercial website devoted to sharing practical information on growing and enjoying rhododendrons. Created and maintained by Valley Forge chapter member Steve Henning."
  • Vancouver Rhododendron Society - "Henning's Rhododendron & Azalea Pages Comprehensive Information on rhododendron, azalea, vireya species "
  • Victoria Rhododendron Society - "A VRS Member-Recommended Link."
  • Wauu - "Descriptions, culture, and trouble-shooting, as well as companion plants."
  • Websters Dictionary Online - "Extensive information on rhododendron species: the history of their discovery, botanical details, toxicity, classifications, cultural conditions, care for common problems, and suggestions for companion plants by Steve Henning."
  • West Virginia State Treasurer's Office - "The Henning's Page contains various information on this plant such as different species, problems with the plant, books on the subject, and links to other sites."
  • Wikipedia - "Extensive information on rhododendron species: the history of their discovery, botanical details, toxicity, classification, cultural conditions, care for common problems, and suggestions for companion plants by Steve Henning."
  • Yahoo - "Henning's rhododendron and azalea pages feature descriptions, cultural, and trouble shooting pages as well as companion plants."

References: Books Used In Preparing This Site Listed by Title

Click here for books listed by author

  • "All About Azaleas, Camellias & Rhododendrons (Ortho)" by Fell, Derek snf Fred Galle, Gary Hespenheide, (2001)
  • "American Azaleas" by Towe, L. Clarence (2004)
  • "American Rhododendron Hybrids" by Kraxberger, Meldon,editor (1980)
  • "Azakeas, Kinds and Culture" by Hume, H. Harold (1954)
  • "Azalea Book, The," by Lee, Frederic Paddock (1958)
  • "Azalea Book, The," by Lee, Frederic Paddock (1980)
  • "Azalea Handbook, The," by Lee, Coe, Morrison (1953)
  • "Azaleas and Camelias" by Hume, H. Harold (1931)
  • "Azaleas, Camelias, and Rhododendrons (Ortho)" by Reilley, H. Edward (2001)
  • "Azaleas" by Fairweather, Christopher (1988)
  • "Azaleas" by Galle, Fred C. (1988)
  • "Big Leaf Rhododendrons: Growng the Giants of the Genus *NEW*" by Church, Glyn and Graham Smith, & Pat Greenfield (2015)
  • "Book of Rhododendrons, The," by Kneller, Marianna (1995)
  • "Brocade Pillow: Azaleas of Old Japan, A," by Ito, Iheo (1984)
  • "Catalogue" by Whitney Gardens and Nursery (2013)
  • "Compendium of Rhododendron and Azalea Diseases *NEW*" by Linderman, Robert G. and Dr. Michael Benson (2014)
  • "Compendium of Rhododendron and Azalea Diseases" by Coyier, Duane and Martha Roane (1986)
  • "Contributions Toward A Classificationof Rhododendrons" by Luteyn, James L. (1978)
  • "Cox's Guide to Choosing Rhododendrons" by Cox, Peter and Kenneth Cox (1995)
  • "Crossing the Rubicon" by Coker, Brian (1998)
  • "Cultivation of Rhododendrons, The," by Cox, Peter A. (1994)
  • "Dexter Estate, The," by Cowels, Evelyn (1986)
  • "Dwarf Rhododendrons" by Cox, Peter A. (1973)
  • "Encyclopedia of Rhododendron Hybrids" by Cox, Peter A. Cox, Kenneth N.E. (1988)
  • "Encyclopedia of Rhododendron Species" by Cox, Peter A. Cox, Kenneth N.E. (2001)
  • "Fungi on Rhododendron : A World Reference" by Palm, Farr, Esteban, and (1996)
  • "Gardening With Rhododendrons" by Richards, Murray (1994)
  • "Getting Started With Rhododendrons and Azaleas" by Clarke, Jay Harold (1983)
  • "Glenn Dale Azaleas, The," by Morrison, B. Y. (1953)
  • "Great American Azaleas" by Darden, Jim (1985)
  • "Greer's Guidebook to Available Rhododendrons" by Greer, Harold E. (1996)
  • "Greer's Guidebook to Rhododendrons" by Greer, Harold E. (1982)
  • "Growing Rhododendrons and Azaleas" by Bryant, Geoff (1996)
  • "Growing Rhododendrons in New England" by Parks, J. B. (1999)
  • "Growing Rhododendrons, A Garden Guide (Pukeiti)" by Harrup, David (1996)
  • "Growing Rhododendrons" by Francis, Richard (1998)
  • "Guide to Rhododendrons, A," by Cox, Kenneth (2005)
  • "Handbook of Rhododendrons, The," by Frye, Nearing, Cox, Bowers, et.al. University of Washington (1946)
  • "Hardy Rhododendron Species" by Cullen, James (2005)
  • "Hardy Rhododendrons" by Street, Frederick (1955)
  • "Himalayan Garden, The," by Jermyn, Jim (2001)
  • "History of the Rhododendron Species: Genesis of a Botanic Garden" by Clarence Barrett Foundation (1994)
  • "How To Identify Rhododendron And Azalea Problems" by Antonelli, Art (1999)
  • "Hybrids and Hybridizers, Rhododendrons and Azaleas" by Livingston, Philip A. and Franklin H. West (1978)
  • "Identifying, Treating & Avoiding Azalea and Rhododendron Problems" by Scott, (WSU) (2015)
  • "Illustrated Rhododendron: Portrayed Through the Artwork of Curtis's Botanical Magazine" by Halliday, Pat and John Curtis (Illustrator) (2001)
  • "Kalmia : Mountain Laurel and Related Species" by Jaynes, Richard A. (1997)
  • "Larger Rhododendron Species" by Cox, Peter A. (1990)
  • "Laurel Book, The" by Jaynes, Richard A. (1974)
  • "Making the most of Rhododendrons and Azaleas" by Fairweather, Christopher (1993)
  • "Making the most of Rhododendrons and Azaleas" by Fairweather, Christopher (1993)
  • "Modern Rhododendrons" by Cox, E. H. M. and P. A. Cox (1956)
  • "Monograph on Azaleas, A," by Wilson, Ernest Henry (1921)
  • "Native and Introduced Azaleas for Southern Gardens" by Galle, Fred (1962)
  • "Pacific Coast Rhododendron Story, The," by Nelson, Sonja (Compiler) (2001)
  • "Phenology of Cultivated Rhododendrons" by Wade, L. Keith (1965)
  • "Plantsman's Guide to Rhododendrons, A," by Cox, Kenneth (2008)
  • "Plantsman's Paradise, Travels in China" by Lancaster, Roy * (2008)
  • "Pocket Guide to Rhododendron Species" by McQuire, J. F. and Robinson, M.L.A. (2010)
  • "Production of Florist Azaleas (Growers Handbook, Vol 6)" by Armitage, Allan M. and Roy A. Larson (2003)
  • "Public Rhododendron gardens of Vancouver Island *NEW*, The," by Efford, Ian E. with Alan Campbell & Susan Lightburn * (2015)
  • "Pukeiti: New Zealand's Finest Rhododendron Garden" by Greenfield, Pat (1997)
  • "Resplendence of Rhododendrons, A," by McCarter and Fuller (2005)
  • "Rhododendron Basics" by Greer, Harold E. * (1996)
  • "Rhododendron Handbook, Rhododendron Species in Cultivation, The," by Royal Horticultural Society (1980)
  • "Rhododendron Hybrids" by Salley, Homer E. and Harold E. Greer (2005)
  • "Rhododendron Information" by American Rhododendron Society (Jay Harold Clarke) (1967)
  • "Rhododendron Leaf - A Study of the Epidermal Appendages, The," by Cowan, J. M. (1950)
  • "Rhododendron Notes" by American Rhododendron Society (Jay Harold Clarke) (1968)
  • "Rhododendron Pocketbook, The," by Cooper, W. E. Shewell- (1955)
  • "Rhododendron Portraits" by Van Gelderen, D.M. (2005)
  • "Rhododendron Species : Azaleas Vol 4, The," by Davidian, H. H. (2003)
  • "Rhododendron Species : Vol 3 Elepidotes Neriiflorum-Thomsonii, The," by Davidian, H. H. (1982)
  • "Rhododendron Species Dictionary" by Spady, Herbert A. (1984)
  • "Rhododendron Species, Vol 1: Lepidotes" by Davidian, H.H. (2003)
  • "Rhododendron Species, Vol 2 Part 1 : Elepidotes, Arboreum-Lacteum" by Davidian, H.H. (2003)
  • "Rhododendron Species: 2006" by Rhododendron Species Foundation (2006)
  • "Rhododendron Species: 2007" by Rhododendron Species Foundation (2007)
  • "Rhododendron Species: 2008" by Rhododendron Species Foundation (2008)
  • "Rhododendron Species: 2009" by Rhododendron Species Foundation (2009)
  • "Rhododendron Species: 2010" by Rhododendron Species Foundation (2010)
  • "Rhododendron Species: 2013" by Rhododendron Species Foundation (2013)
  • "Rhododendron Story, The," by Postan, Cynthia (1996)
  • "Rhododendron Yearbook for 1945, The," by American Rhododendron Society (Dean Collins) (1945)
  • "Rhododendron Yearbook for 1946, The," by American Rhododendron Society (Dean Collins) (1946)
  • "Rhododendron Yearbook for 1947, The," by American Rhododendron Society (Robert Moulton Gatke) (1947)
  • "Rhododendron Yearbook for 1948, The," by American Rhododendron Society (Robert Moulton Gatke) (1948)
  • "Rhododendron Yearbook for 1949, The," by American Rhododendron Society (Robert Moulton Gatke) (1949)
  • "Rhododendron-Park Bremen" by Monch, Jochen and Hartwig Schepker (2010)
  • "Rhododendron, Azaleas, Magnolias, Camelias, and Ornamental Cherries" by Johnson, A. T. and F. C. Puddle (1948)
  • "Rhododendrons (RHS/Wisley)" by Cox, Peter A. (1992)
  • "Rhododendrons (The New Plant Library)" by Hawthorne, Lin (1999)
  • "Rhododendrons (Wisley)" by Cox, Peter A. (1980)
  • "Rhododendrons 1956" by American Rhododendron Society (Jay Harold Clarke) (1956)
  • "Rhododendrons and Azaleas (Present Day Gardening)" by Watson, William (?)
  • "Rhododendrons and Azaleas (Sunset)" by Eddinger, Philip (1999)
  • "Rhododendrons and Azaleas: A Colour Guide" by Cox, Kenneth (2005)
  • "Rhododendrons and Azaleas" by Berrisford, Judith Mary (1973)
  • "Rhododendrons and Azaleas" by Bonar, Ann (1993)
  • "Rhododendrons and Azaleas" by Bowers, Clement Gray (1960)
  • "Rhododendrons and Azaleas" by Bryant, Geoff (2001)
  • "Rhododendrons and Azaleas" by Kessell, Mervyn (1982)
  • "Rhododendrons and Azaleas" by La Croix, I. F. (1973)
  • "Rhododendrons and Azaleas" by Street, Frederick (1957)
  • "Rhododendrons and Azaleas" by Watson, William (?)
  • "Rhododendrons and Magnolias" by Bartrum, Douglas (1957)
  • "Rhododendrons for Amatuers" by Cox, E. H. M. (1924)
  • "Rhododendrons for Every Garden" by Wakefield, Geoffrey R. (1965)
  • "Rhododendrons for Everyone" by Wakefield, Geoffrey R. (1926)
  • "Rhododendrons for Your Garden" by American Rhododendron Society (Jay Harold Clarke) (1961)
  • "Rhododendrons in America" by Van Veen, Ted (1980)
  • "Rhododendrons in New Zealand" by Tapley, Mrgaret (1989)
  • "Rhododendrons in the Landscape" by Nelson, Sonja (2000)
  • "Rhododendrons of China" by Guomei, Feng * (1992)
  • "Rhododendrons of China" by Guomei, Feng & Yang Zenghong, Guo-Mei Feng (Editors) * (1999)
  • "Rhododendrons of China" by Young, Judy and Lu-Sheng Chong (1981)
  • "Rhododendrons of Darjeeling and Sikkim Himalayas" by Sain, M. (1974)
  • "Rhododendrons of Milner Gardens and Woodland, The," by Milner Gardens (?)
  • "Rhododendrons of the World" by Leach, David G. (1961)
  • "Rhododendrons You Should Meet" by Van Veen, Ted (1996)
  • "Rhododendrons, A Guide to Selecting and Enjoying" by Rhodes, Janet (1982)
  • "Rhododendrons: A Care Manual" by Cox, Kenneth and N. E. Cox, Laurel Glen (1998)
  • "Rhododendrons" by Cox, Peter Alfred (1989)
  • "Rhododendrons" by Krüssmann, Gerd (1970)
  • "Rhododendrons" by Street, Frederick (1965)
  • "Rhododendrons" by Street, John (1987)
  • "Rhododendrons" by Wakefield, Geoffrey R. (1950)
  • "Riddle of the Tsangpo Gorges" by Ward, Frank Kingdon & Kenneth Cox, Ken Storm Jr., Ian Baker (2008)
  • "Rothschild Gardens, The," by Rothschild DSc, Miriam & Andrew Lawson, Kate Garton, Lionel de Rothschild (2000)
  • "Rothschild Rhododendrons: The Gardens at Exbury" by Phillips, C. E. Lucas and Peter Barber (1979)
  • "Royal Botanic Garden, Edinburgh 2008" by Royal Botanic Garden, Edinburgh (2008)
  • "Royal Botanic Garden, Edinburgh 2009" by Royal Botanic Garden, Edinburgh (2009)
  • "Satsuki Azaleas for Bonsai and Azalea Enthusiasts" by Callaham, Robert Z * (2006)
  • "Seeds of Adventure, In Search of Plants" by Cox, Peter and Peter Hutchison * (2008)
  • "Selected Rhododendron Glossary and Botanical Terms" by Nelson, Pat and Marlene Buffington, Nadine Henry (1982)
  • "Sikkim and the World of Rhododendrons" by Pradham, Udai C. and Sonam T. Lachungpa (1990)
  • "Smaller Rhododendrons, The," by Cox, Peter A. (1990)
  • "Southern Living Azaleas" by Galle, Fred (1974)
  • "Species of Rhododendrons, The," by Stevenson, J. B. (The Rhododendron Society) (1947)
  • "Study of Species for New England, A," by Masschussetts Chapter, ARS (2000)
  • "Success with Rhododendrons and Azaleas" by Kosel, Andrea (1999)
  • "Success with Rhododendrons and Azaleas" by Reilley, H. Edward (2004)
  • "Tales of the Rose Tree" by Brown, Jane (2006)
  • "Titere Gardens, Rotorua" by Robertson, B. R. (1998)
  • "Top-Rated Azaleas and Rhododendrons (Golden)" by Latimer (Horticulturalist Associates Inc.) (1983)
  • "Vireya Rhododendrons" by Smith, E. W. (1998)
  • "Vireyas: A Practical Gardening Guide" by Kenyon, John and Jacqueline Walker (2003)
  • "Winter Hardy Rhododendrons and Azaleas" by Bowers, Clement Gray (1954)
  • "Winter Hardy Rhododendrons and Azaleas" by Bowers, Clement Gray (1954)
  • "Wit and Wisdom of Norman Todd" by Todd, Norman (2011)
  • "Woody Ornamental Insect, Mite & Disease Management" by Hock, (Penn State) (1995)
References Listed By Title Return to Top References Listed By Author

References: Books Used In Preparing This Site Listed By Author

Click here for books listed by title

  • American Rhododendron Society (Dean Collins): "Rhododendron Yearbook for 1945, The," (1945)
  • American Rhododendron Society (Dean Collins): "Rhododendron Yearbook for 1946, The," (1946)
  • American Rhododendron Society (Jay Harold Clarke): "Rhododendron Information" (1967)
  • American Rhododendron Society (Jay Harold Clarke): "Rhododendron Notes" (1968)
  • American Rhododendron Society (Jay Harold Clarke): "Rhododendrons 1956" (1956)
  • American Rhododendron Society (Jay Harold Clarke): "Rhododendrons for Your Garden" (1961)
  • American Rhododendron Society (Robert Moulton Gatke): "Rhododendron Yearbook for 1947, The," (1947)
  • American Rhododendron Society (Robert Moulton Gatke): "Rhododendron Yearbook for 1948, The," (1948)
  • American Rhododendron Society (Robert Moulton Gatke): "Rhododendron Yearbook for 1949, The," (1949)
  • Antonelli, Art: "How To Identify Rhododendron And Azalea Problems" (1999)
  • Armitage, Allan M. and Roy A. Larson: "Production of Florist Azaleas (Growers Handbook, Vol 6)" (2003)
  • Bartrum, Douglas: "Rhododendrons and Magnolias" (1957)
  • Berrisford, Judith Mary: "Rhododendrons and Azaleas" (1973)
  • Bonar, Ann: "Rhododendrons and Azaleas" (1993)
  • Bowers, Clement Gray: "Rhododendrons and Azaleas" (1960)
  • Bowers, Clement Gray: "Winter Hardy Rhododendrons and Azaleas" (1954)
  • Bowers, Clement Gray: "Winter Hardy Rhododendrons and Azaleas" (1954)
  • Brown, Jane: "Tales of the Rose Tree" (2006)
  • Bryant, Geoff: "Growing Rhododendrons and Azaleas" (1996)
  • Bryant, Geoff: "Rhododendrons and Azaleas" (2001)
  • Callaham, Robert Z *: "Satsuki Azaleas for Bonsai and Azalea Enthusiasts" (2006)
  • Church, Glyn and Graham Smith, & Pat Greenfield: "Big Leaf Rhododendrons: Growng the Giants of the Genus *NEW*" (2015)
  • Clarence Barrett Foundation: "History of the Rhododendron Species: Genesis of a Botanic Garden" (1994)
  • Clarke, Jay Harold: "Getting Started With Rhododendrons and Azaleas" (1983)
  • Coker, Brian: "Crossing the Rubicon" (1998)
  • Cooper, W. E. Shewell-: "Rhododendron Pocketbook, The," (1955)
  • Cowan, J. M.: "Rhododendron Leaf - A Study of the Epidermal Appendages, The," (1950)
  • Cowels, Evelyn: "Dexter Estate, The," (1986)
  • Cox, E. H. M. and P. A. Cox: "Modern Rhododendrons" (1956)
  • Cox, E. H. M.: "Rhododendrons for Amatuers" (1924)
  • Cox, Kenneth and N. E. Cox, Laurel Glen: "Rhododendrons: A Care Manual" (1998)
  • Cox, Kenneth: "Guide to Rhododendrons, A," (2005)
  • Cox, Kenneth: "Plantsman's Guide to Rhododendrons, A," (2008)
  • Cox, Kenneth: "Rhododendrons and Azaleas: A Colour Guide" (2005)
  • Cox, Peter A. Cox, Kenneth N.E.: "Encyclopedia of Rhododendron Hybrids" (1988)
  • Cox, Peter A. Cox, Kenneth N.E.: "Encyclopedia of Rhododendron Species" (2001)
  • Cox, Peter A.: "Cultivation of Rhododendrons, The," (1994)
  • Cox, Peter A.: "Dwarf Rhododendrons" (1973)
  • Cox, Peter A.: "Larger Rhododendron Species" (1990)
  • Cox, Peter A.: "Rhododendrons (RHS/Wisley)" (1992)
  • Cox, Peter A.: "Rhododendrons (Wisley)" (1980)
  • Cox, Peter A.: "Smaller Rhododendrons, The," (1990)
  • Cox, Peter Alfred: "Rhododendrons" (1989)
  • Cox, Peter and Kenneth Cox: "Cox's Guide to Choosing Rhododendrons" (1995)
  • Cox, Peter and Peter Hutchison *: "Seeds of Adventure, In Search of Plants" (2008)
  • Coyier, Duane and Martha Roane: "Compendium of Rhododendron and Azalea Diseases" (1986)
  • Cullen, James: "Hardy Rhododendron Species" (2005)
  • Darden, Jim: "Great American Azaleas" (1985)
  • Davidian, H. H.: "Rhododendron Species : Azaleas Vol 4, The," (2003)
  • Davidian, H. H.: "Rhododendron Species : Vol 3 Elepidotes Neriiflorum-Thomsonii, The," (1982)
  • Davidian, H.H.: "Rhododendron Species, Vol 1: Lepidotes" (2003)
  • Davidian, H.H.: "Rhododendron Species, Vol 2 Part 1 : Elepidotes, Arboreum-Lacteum" (2003)
  • Eddinger, Philip: "Rhododendrons and Azaleas (Sunset)" (1999)
  • Efford, Ian E. with Alan Campbell & Susan Lightburn *: "Public Rhododendron gardens of Vancouver Island *NEW*, The," (2015)
  • Fairweather, Christopher : "Azaleas" (1988)
  • Fairweather, Christopher: "Making the most of Rhododendrons and Azaleas" (1993)
  • Fairweather, Christopher: "Making the most of Rhododendrons and Azaleas" (1993)
  • Fell, Derek snf Fred Galle, Gary Hespenheide: "All About Azaleas, Camellias & Rhododendrons (Ortho)" (2001)
  • Francis, Richard: "Growing Rhododendrons" (1998)
  • Frye, Nearing, Cox, Bowers, et.al. University of Washington: "Handbook of Rhododendrons, The," (1946)
  • Galle, Fred C.: "Azaleas" (1988)
  • Galle, Fred: "Native and Introduced Azaleas for Southern Gardens" (1962)
  • Galle, Fred: "Southern Living Azaleas" (1974)
  • Greenfield, Pat: "Pukeiti: New Zealand's Finest Rhododendron Garden" (1997)
  • Greer, Harold E. *: "Rhododendron Basics" (1996)
  • Greer, Harold E.: "Greer's Guidebook to Available Rhododendrons" (1996)
  • Greer, Harold E.: "Greer's Guidebook to Rhododendrons" (1982)
  • Guomei, Feng *: "Rhododendrons of China" (1992)
  • Guomei, Feng & Yang Zenghong, Guo-Mei Feng (Editors) *: "Rhododendrons of China" (1999)
  • Halliday, Pat and John Curtis (Illustrator) : "Illustrated Rhododendron: Portrayed Through the Artwork of Curtis's Botanical Magazine" (2001)
  • Harrup, David: "Growing Rhododendrons, A Garden Guide (Pukeiti)" (1996)
  • Hawthorne, Lin: "Rhododendrons (The New Plant Library)" (1999)
  • Hock, (Penn State): "Woody Ornamental Insect, Mite & Disease Management" (1995)
  • Hume, H. Harold: "Azakeas, Kinds and Culture" (1954)
  • Hume, H. Harold: "Azaleas and Camelias" (1931)
  • Ito, Iheo: "Brocade Pillow: Azaleas of Old Japan, A," (1984)
  • Jaynes, Richard A.: "Kalmia : Mountain Laurel and Related Species" (1997)
  • Jaynes, Richard A.: "Laurel Book, The" (1974)
  • Jermyn, Jim: "Himalayan Garden, The," (2001)
  • Johnson, A. T. and F. C. Puddle: "Rhododendron, Azaleas, Magnolias, Camelias, and Ornamental Cherries" (1948)
  • Kenyon, John and Jacqueline Walker: "Vireyas: A Practical Gardening Guide" (2003)
  • Kessell, Mervyn: "Rhododendrons and Azaleas" (1982)
  • Kneller, Marianna: "Book of Rhododendrons, The," (1995)
  • Kosel, Andrea: "Success with Rhododendrons and Azaleas" (1999)
  • Kraxberger, Meldon,editor: "American Rhododendron Hybrids" (1980)
  • Krüssmann, Gerd: "Rhododendrons" (1970)
  • La Croix, I. F.: "Rhododendrons and Azaleas" (1973)
  • Lancaster, Roy *: "Plantsman's Paradise, Travels in China" (2008)
  • Latimer (Horticulturalist Associates Inc.): "Top-Rated Azaleas and Rhododendrons (Golden)" (1983)
  • Leach, David G.: "Rhododendrons of the World" (1961)
  • Lee, Coe, Morrison: "Azalea Handbook, The," (1953)
  • Lee, Frederic Paddock: "Azalea Book, The," (1958)
  • Lee, Frederic Paddock: "Azalea Book, The," (1980)
  • Linderman, Robert G. and Dr. Michael Benson: "Compendium of Rhododendron and Azalea Diseases *NEW*" (2014)
  • Livingston, Philip A. and Franklin H. West: "Hybrids and Hybridizers, Rhododendrons and Azaleas" (1978)
  • Luteyn, James L.: "Contributions Toward A Classificationof Rhododendrons" (1978)
  • Masschussetts Chapter, ARS: "Study of Species for New England, A," (2000)
  • McCarter and Fuller: "Resplendence of Rhododendrons, A," (2005)
  • McQuire, J. F. and Robinson, M.L.A.: "Pocket Guide to Rhododendron Species" (2010)
  • Milner Gardens: "Rhododendrons of Milner Gardens and Woodland, The," (?)
  • Monch, Jochen and Hartwig Schepker: "Rhododendron-Park Bremen" (2010)
  • Morrison, B. Y.: "Glenn Dale Azaleas, The," (1953)
  • Nelson, Pat and Marlene Buffington, Nadine Henry: "Selected Rhododendron Glossary and Botanical Terms" (1982)
  • Nelson, Sonja (Compiler): "Pacific Coast Rhododendron Story, The," (2001)
  • Nelson, Sonja: "Rhododendrons in the Landscape" (2000)
  • Palm, Farr, Esteban, and: "Fungi on Rhododendron : A World Reference" (1996)
  • Parks, J. B. : "Growing Rhododendrons in New England" (1999)
  • Phillips, C. E. Lucas and Peter Barber: "Rothschild Rhododendrons: The Gardens at Exbury" (1979)
  • Postan, Cynthia: "Rhododendron Story, The," (1996)
  • Pradham, Udai C. and Sonam T. Lachungpa: "Sikkim and the World of Rhododendrons" (1990)
  • Reilley, H. Edward: "Azaleas, Camelias, and Rhododendrons (Ortho)" (2001)
  • Reilley, H. Edward: "Success with Rhododendrons and Azaleas" (2004)
  • Rhodes, Janet: "Rhododendrons, A Guide to Selecting and Enjoying" (1982)
  • Rhododendron Species Foundation: "Rhododendron Species: 2006" (2006)
  • Rhododendron Species Foundation: "Rhododendron Species: 2007" (2007)
  • Rhododendron Species Foundation: "Rhododendron Species: 2008" (2008)
  • Rhododendron Species Foundation: "Rhododendron Species: 2009" (2009)
  • Rhododendron Species Foundation: "Rhododendron Species: 2010" (2010)
  • Rhododendron Species Foundation: "Rhododendron Species: 2013" (2013)
  • Richards, Murray: "Gardening With Rhododendrons" (1994)
  • Robertson, B. R. : "Titere Gardens, Rotorua" (1998)
  • Rothschild DSc, Miriam & Andrew Lawson, Kate Garton, Lionel de Rothschild: "Rothschild Gardens, The," (2000)
  • Royal Botanic Garden, Edinburgh: "Royal Botanic Garden, Edinburgh 2008" (2008)
  • Royal Botanic Garden, Edinburgh: "Royal Botanic Garden, Edinburgh 2009" (2009)
  • Royal Horticultural Society: "Rhododendron Handbook, Rhododendron Species in Cultivation, The," (1980)
  • Sain, M.: "Rhododendrons of Darjeeling and Sikkim Himalayas" (1974)
  • Salley, Homer E. and Harold E. Greer: "Rhododendron Hybrids" (2005)
  • Scott, (WSU): "Identifying, Treating & Avoiding Azalea and Rhododendron Problems" (2015)
  • Smith, E. W.: "Vireya Rhododendrons" (1998)
  • Spady, Herbert A.: "Rhododendron Species Dictionary" (1984)
  • Stevenson, J. B. (The Rhododendron Society): "Species of Rhododendrons, The," (1947)
  • Street, Frederick: "Hardy Rhododendrons" (1955)
  • Street, Frederick: "Rhododendrons and Azaleas" (1957)
  • Street, Frederick: "Rhododendrons" (1965)
  • Street, John: "Rhododendrons" (1987)
  • Tapley, Mrgaret: "Rhododendrons in New Zealand" (1989)
  • Todd, Norman: "Wit and Wisdom of Norman Todd" (2011)
  • Towe, L. Clarence: "American Azaleas" (2004)
  • Van Gelderen, D.M.: "Rhododendron Portraits" (2005)
  • Van Veen, Ted: "Rhododendrons in America" (1980)
  • Van Veen, Ted: "Rhododendrons You Should Meet" (1996)
  • Wade, L. Keith: "Phenology of Cultivated Rhododendrons" (1965)
  • Wakefield, Geoffrey R.: "Rhododendrons for Every Garden" (1965)
  • Wakefield, Geoffrey R.: "Rhododendrons for Everyone" (1926)
  • Wakefield, Geoffrey R.: "Rhododendrons" (1950)
  • Ward, Frank Kingdon & Kenneth Cox, Ken Storm Jr., Ian Baker: "Riddle of the Tsangpo Gorges" (2008)
  • Watson, William: "Rhododendrons and Azaleas (Present Day Gardening)" (?)
  • Watson, William: "Rhododendrons and Azaleas" (?)
  • Whitney Gardens and Nursery: "Catalogue" (2013)
  • Wilson, Ernest Henry: "Monograph on Azaleas, A," (1921)
  • Young, Judy and Lu-Sheng Chong: "Rhododendrons of China" (1981)
References Listed By Title Return to Top References Listed By Author

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Last Updated: July 6, 2020