Rhododendrons are believed to have evolved from camellias, which had evolved from magnolias. The first Rhododendron to be classified and named was R. hirsutum. It was discovered by the 16th century Flemish botanist, Charles l'Ecluse, who later became called Clusius. When it was introduced to Britain in 1656 from the Swiss Alps, R. hirsutum (the Alpine Rose) was the first species of Rhododendron in cultivation. Native of the central and eastern Alps and of N.W. Yugoslavia, it was cultivated by John Tradescant 1656.
When the first azaleas arrived in England is in dispute. Jane Brown, Fred Galle, Peter Cox and Ken Cox say exploration in America came in 1680 as a result of R. viscosum and R. periclymenoides seed collected in the North America by John Bannister, an English missionary, and sent to the Bishop of London, Henry Compton, in England. H. H. Davidian reports that John Bannister sent Henry Compton drawings of R. viscosum in 1691.
Davidian and David Leach state that the first actual azalea plants to be grown in England were those from seed or plants collected by John Bartram. A partnership between English Quaker Peter Collinson and botanist/farmer John Bartram of Pennsylvania led to the importation to England of the American natives, R. canescens, R. periclymenoides, and R. viscosum in 1734, and R. maximum in 1736.
As a historical reference, it should be noted that the Japanese were raising hybrids of R. indicum and R. tamurae in the 17th century. The Japanese book "A Brocade Pillow," which was published in 1692, carefully describes and classifies the color patterns of these plants that are called Satsuki Azaleas today.
It has been recorded that the first amateur collector in China was James Cunningham. He entered the service the East India Company, and in 1698 he was sent as a surgeon to Amoy, China. Later, in 1701, he set sail to Chusan (China) where he stayed for more than two years, and it was in this area where he made his collection. Cunningham sent home a large consignment of over 600 dried specimens. In 1709 he embarked to return to England and apparently died on the voyage home.
R. ferrugineum, another species from the European Alps also called the Alpine Rose, came along in 1740. The two plants called the Alpine Rose are perhaps the only rhododendrons to do well in limestone soils. Claes Alstoemer discovered R. ponticum, a native of Armenia, the country that was known to the ancients as Pontus, was found in Spain between Cadiz and Gibraltar around 1750 and it reached England in 1763. Some regions of the UK are overrun by this species.
In 1735, Karl von Linne (Latinized Linnaeus), a Swedish naturalist, proposed the currently accepted binomial system of nomenclature to replace the cumbersome descriptive method that varied from one author to another, creating much confusion. Linnaeus used the term rhododendron in 1753 for only a few species: R. ponticum of Asia Minor, R. dauricum of Siberia, R. maximum from America, R. ferrugineum and R. hirsutum of the European Alps, and the circumpolar R. lapponicum. In Linnaeus' 'Supplement', R. chrysanthum was described. He listed Azalea as a separate genus, namely A. lutea (now R. indicum), and A. viscosa (later R. nudiflora and now R. viscosum). Linnaeus first described R. canadense, the Rhodora Azalea, in 1762. It is found from Eastern Quebec to Newfoundland and Nova Scotia, and south the northern parts of Pennsylvania and New Jersey. Return to Top
The German naturalist Pallas described four rhododendron species native to eastern Europe and to Asia: R. dauricum in 1780, R. camtschaticum in 1784, R. flavum (which is now called R. luteum) in 1793, and R. chrysanthum in 1796.
Exact date of discovery for R. flammeum (also knows as R. speciosum) is not known, but plants of this species were first described by Aiton at Kew Gardens in 1789 and were probably sent there by William Bartram prior to that date.
R. macrophyllum, the Pacific Rhododendron, found in the North America from Northern California to British Columbia was discovered in 1792 by Archibald Menzies Return to Top
R. carolinianum (the Carolina form of R. minus) was first collected by A. Michaux in 1792 and R. calendulaceum (the flame azalea) was first collected by A. Michaux in 1795 from the Blue Ridge Mountains of North Carolina.
By 1800 there were only twelve species known in cultivation. Gifts from the Russian collector, Count Pushkin, R. caucasicum arrived in England in 1803 and R. minus came from America in the first few years of the new century.
R. obtusum, known as a garden plant for centuries by the Japanese who called the shrub "Kirishima-tsutsuji", was mentioned in 1712 by Kaempfer, who used the Japanese name. It is a native of Japan but was introduced to England in 1844 by Robert Fortune from a Chinese garden. This 'wild' form, called R. obtusum f. japonicum by E. H. Wilson was considered by him to be the parent of all "Kurume Azaleas". This species was described as Azalea indica by Thunberg in 'Flowers of Japan' in 1784. Return to Top
In 1809 R. catawbiense was introduced from North Carolina. It later became the principal source of hardiness in the hybrids that have graced our gardens for generations. It was collected by John Fraser and his son while collecting plants for Russian Emperor Paul. R. arborescens was first described by John Bartram in 1814.
The first of many Rhododendrons that were to come from southeastern Asia was the tree species, R. arboreum, with blood-red flowers, which was discovered by Captain Hardwicke in 1799 and arrived from India in 1811. In 1821 George Don introduced R. anthopogen and R. setosum from Asia. In 1823, R. molle, destined to become famous as one of the parents of the Mollis hybrids, was introduced from China. In 1832, R. zeylanicum (a subspecies of R. arboreum) came into England from Ceylon. From the Himalayan regions of Nepal and Sikkim, R. campanulatum was introduced in 1825 and the beautiful R. barbatum was introduced in 1849. R. scarbum was introduced by George Don in 1834 from Japan.
R. mucronatum (variously described as Azalea rosmarinifolia, (Johannes) Burman (1768); Azalea mucronata (Carl Ludwig) Blume (1823); Azalea indica alba, Lindley (1824); Azalea ledifolia, Hooker (1829) and other names familiar to gardeners), was mentioned by Engelbert Kaempfer in 1712 under its Japanese name "Jedogawa-tsutsuji". According to John Lindley in 1824, this species was sent to Joseph Poole from China to Brookes Nursery at Ball's Pond in 1819. Return to Top
R. japonicum (now known as a subspecies of R. degronianum) was known by other names and is often confused with the Chinese deciduous azalea species R. molle. It is native only to Japan where it is common over a great part of Hondo, the main island and elsewhere. Taken to Holland in 1830 by Philipp Franz von Siebold, it was used in hybridizing with R. molle to produce the "Mollis Azalea".
R. formosanum was introduced from India in 1832 by Wallich.
R. reticulatum, a native of much of Japan, was brought to England by Knight of Chelsea about 1832 to1833, but it may have been lost. Several later introductions were made.
In 1834, Sir William Jackson Hooker introduced R. albiflorum from the West Coast of North America. In 1835, Siebold and Zuccarini introduced R. metternichii (now knows as R. degronianum ssp. degronianum) from Japan. Return to Top
In 1849 and 1850 Sir Joseph Hooker's expedition to Sikkim in the eastern Himalayas discovered forty-five new species including the yellow-flowered R. campylocarpum and R. wightii; the red-flowered R. thomsonii; the small trees, R. falconeri, R. grande, and R. hodgsonii, with their enormous leaves; the epiphytes, R. dalhousiae and R. maddenii; the large vigorous R. griffithianum with massive white flowers; and the interesting R. triflorum, R. edgeworthii, R. fulgens, R. niveum, R. wallichii, R. lanatum, R. glaucophyllum, R. cinnabarinum, and R. lepidotum. Booth found R. hookeri and R. nuttalli in Bhutan in 1852. Planchon found R. simsii in 1854. Return to Top
In 1855 Robert Fortune discovered R. ovatum in 1854 and R. fortunei in 1855 in Chekiang, China. It became the foundation of an important series of hybrids hardy in the United States as far north as Boston.
The next wave of exploration in 1881 was the outcome of earlier discoveries by French Catholic missionaries, Péres Armand David, Pere Jean-Marie Delavay and Paul Farges whose discovered were name R. davidii, R. delavayi, R. fargesii, and R. souliei. David also discovered R. calophytum. Delavay also discovered R. ciliicalyx, R. fictolacteum, R. lacteum, R. neriiflorum, and R. campylogynum in 1884; R. crassum and R. haematodes in 1885; R. bullatum, R. irroratum, and R. heliolepis in 1886; R. sulfureum in 1887; and R. racemosum, R. spinuliferum, R. rubiginosum and R. yunnanense in 1889; all in Yunnan, China. Farges also discovered R. adenopodum at 6,000 feet elevation in Szechuan/Hupeh, China. Rev. Souliei discovered R. chasmanthum and R. vernicosum in 1893, R. saluense in 1894, and R. wardii in 1895, in Yunnan, China. Rev. Ernest Faber discovered R. concinnum in Yunnan, China, in 1886. Many of these plants were grown from seed and introduced by Forrest.
In 1885 Baron Ungern-Sternberg discovered R. smirnowii and R. ungernii in the Caucasus Mountains. Return to Top
The discoveries by the French missionaries led to a systematic search stated in 1899 and followed up in 1903-4 by Dr. Ernest Wilson for plants in China. Wilson found R. discolor, R. praevernum and R. ponticum in 1900; R. micranthum and R. sutchuenense in 1901; and R. ambiguum, R. intricatum, R. longesquamatum, R. obiculare, R. oreodoxa, R. tricanthum, R. wasonii, and R. davidsonianum in 1904 in Szechuan, China. Wilson introduced R. insigne R. williamsianum in 1908 and R. moupinense in 1909.
Wilson's work lead to a flood of expeditions by plant explorers to Asia. In 1904 George Forrest and Reginald Farrer explored Yunnan, China. Forrest discovered R. haemaleum and R. strigillosum in 1904; R. forrestii in 1905; R. oreotrephes in 1906; R. fulvum and R. sinogrande in 1912; R. puralbum, R. scintillans, and R. russatum in 1913; R. griersonianum and R. meddianum in 1917; R. keleticum and R. scyphocalyx in 1919; and R. taggianum in 1925. Forrest's and Farrer's work was carried on by Captain F. Kingdon-Ward in 1911, and Dr. Joseph F. Rock in 1920, the partners Ludlow and Sheriff and others. Kingdon-Ward discovered R. chryseum at 13,000 feet in Yunnan, China, in 1912; R. hippophaeoides at 12,000 feet in Yunnan, China, in 1913; R. megacalyx at 8,000 feet and R. calostrotum at 11,000 feet in Burma in 1914; R. leucaspis and R. valentinianum at 11,000 in Yunnan, China; R. pemakoense in Tibet in 1924 and R. recurvoides in July 1926 in the valley of the Di Chu in Upper Burma. Farrer and Kingdon-Ward discovered R. aperantum, which was introduced by Forrest. Farrer discovered R. sperabile in Tibet in 1919. Forrest found and introduced R. stewartianum in Yunnan, China, in 1904; R. impeditum in Yunnan, China, in 1911; R. diaprepes in Yunnan, China, in 1913; R. eriogynum in Yunnan, China, in 1914; and R. didymum, R. eclecteum and R. eudoxum in Tibet in 1917. Farrer discovered R. caloxanthum in the Tibet/Yunnan region in 1919 and R. tephropeplum in Burma in 1920. Two new species, R. concatenans and R. xanthocodon were identified from seed collected by Kingdon-Ward. Return to Top
Meanwhile Dr. Augustine Henry, a medical officer, discovered R. augustinii in Szechuan, China, and R. racemosum was discovered by Delavay in Yunnan, China, in 1889. R. griersonianum and R. arizelum were discovered by George Forest in 1917 at about 10,000 feet elevation in Yunnan, China. Return to Top
In 1937, R. aberconwayi was grown from seed from eastern Yunnan sent by Chinese assistants of George Forest to Lord Aberconway after Forest's death in 1932. Return to Top
Most rhododendron species, over 900, are found in Southeast Asia, ranging from the Himalayas through Tibet, Burma, China, Thailand, Viet Nam, to Malaysia, Indonesia, Philippines and New Guinea. The distribution of native species extends down to northern Australia, up to Siberia, and around the world. Europe has 4 species, and in North America about 28 species are found. Return to Top
A recent major discovery of a rhododendron is that of R. degronianum ssp. yakushimanum (aka. yakusimanum) first described by Japanese botanist T. Naki in 1920. Fortunately a Japanese botanist and nurseryman Dr. Wada sent two plants to Lionel de Rothschild's garden at Exbury in the south of England in 1932. Many forms of R. yakushimanum have been identified and most are considered to be subspecies of R. degronianum. Some are identified as subspecies of R. makinoi and R. keskei.
Other recent discoveries of new species include the giant yellow flowered R. sinofalconeri, the red species from the Yunnan/Sichuan border R. ochraceum, and the pink dwarf species R. dendrocharis. And more recently Kenneth Cox led an expedition to Tibet that discovered R. bulu and R. dignabile.
Two deciduous azalea species were recently discovered in Alabama (USA). R. eastmanii was discovered by Charles Eastman in 1980s and named in 1999. R. colemanii was discovered S. D. Coleman, Sr., in 1990s and named in 2008.
Directory of Contents for Henning's Rhododendron & Azalea Pages
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