There are seventeen varieties of North American Native Azaleas:
Much of the material shown below was assembled by Don Hyatt, George McLellan, and Dr. Sandra McDonald and presented at a 2000 Convention lecture
References are shown at the end of this page.
Click on any of the “accordions” to open. Clicking on the distribution maps, and on some of the images, will bring up larger versions.
The White Group
The “White Group” includes six species, five of which have been found growing in the Eastern United States and Canada, and one, R. occidentale, found growing wild on the West Coast. The five Eastern species are: R. alabamense, R. arborescens, R. atlanticum, R. viscosum, and a newly discovered species from South Carolina, R. eastmanii.
Rhododendron alabamense, or the Alabama Azalea, has snowy white flowers with a prominent yellow blotch. Blooming in midseason,
the flowers have a distinct lemon-spice fragrance and measure 0.8 to 1.5 inches across.
Originally thought to be a white form of R. periclymenoides (R. nudiflorum), this plant was first described by Dr. C. Mohr in 1883. It grows naturally in north central Alabama, and western to central Georgia and South Carolina.
R. alabamense is low to medium in height, and spreads by underground stems or stolons. It propagates with relative ease from soft wood cuttings and makes a delightful landscape plant.
Rhododendron arborescens, the Sweet Azalea, has white to blush pink flowers with red stamens, and a very strong fragrance similar to heliotrope. It blooms in late spring to
First described by John Bartram in 1814, this species has a wide distribution in the eastern United States, but can usually be found growing near streams or moist areas. It is sometimes known as the "Smooth Azalea" because the stems are very smooth and do not have hairs similar to the other azaleas.
An excellent landscape plant, R. arborescens can perfume a wide area when in bloom. Relatively easy to propagate, there are a number of excellent forms in the trade.
Rhododendron atlanticum, the Coastal Azalea, is a common understory plant along the south eastern coastal plains of the United States. The white flowers are 1 to 1.5 inches across, but are often blushed with pink on the outside and some have a yellow blotch.
Distribution mapCollected by John Clayton in 1743, this plant was appreciated more in England than in its native land. The plant habit is relatively low but stoloniferous. Spreading by underground stems, R. atlanticum can develop into very large colonies of an acre or more in sandy soils.
R. atlanticum is easy to propagate, and makes a nice landscape plant in heavier soils which will restrict the spreading habit.
Rhododendron eastmanii is a very rare species growing in only a few locations in two South Carolina counties. The current known population is on the order of only 500 plants. Only recently discovered, and its existence first published in November 1999 by Dr. Kathleen Kron and Mike Creel, this is the newest native azalea species. Selected forms are being propagated and will be distributed to the the public in time, so please do not disturb any plants in the wild. Appreciate this rare and beautiful species, and please assist those who are trying to protect its native habitat.
Like several of the native azaleas in the "white group", R. eastmanii flowers after the leaves have expanded. It is clearly different from R. arborescens with the familiar red stamens, since R. eastmanii's stems are not smooth but are covered with hairs, or pubescense. In many ways, it is more closely aligned with the west coast native, R. occidentale, but is obviously different due to its geographical isolation and some other minor characteristics.
Rhododendron occidentale is the only native azalea that grows naturally west of the Rocky Mountains in the United States. It is a difficult garden plant in the South Eastern United States, and seems to object to the heat and humidity that often accompany the summers there.
Rhododendron viscosum now includes two closely related forms that were perviously considered separate species, R. serrulatum and
R. oblongifolium. The fragrant flowers are generally white to pale pink, and bloom after the leaves have fully expanded. Flowers vary in size from 0.75 to 1.5 inches across depending upon the form, but have a long narrow tupe covered with sticky glandular hairs. The species has a wide distribution from Maine to Florda, and westward to Texas.
R. viscosum was the first North American azalea grown in England. Bishop Henry Compton raised the plant in 1680 from seed collected by John Bannister, an English Missionary. The species was an important parent in early hybridzing efforts with deciduous azaleas. It can be distinguished from the other late blooming white, R. arborescens in that the stamens are greenish white rather than red, and the stems are not smooth but contain hairs.
The Pink Group
Rhododendron canadense is a very unusual native azalea species and was originally considered an entirely separate genus, Rhodora. The top three petals of the flower are fused together almost to the end to form a single lobe, whereas the bottom two are completely separate lips. The purplish pink blossoms are approximately 1.5 inches across and have 10 stamens, twice the number of most east coast natives. There are white forms of this species.
First described by Linnaeus in 1762, R. canadenseis a low stoloniferous shrub that grows along stream banks and in swamps in eastern North America from Pennsylvania into Labrador. The most northern of the east coast native azaleas, the species is very cold hardy but a difficult plant where summers are hot and dry.
Rhododendron canescens, the piedmont or Florida Pinxter Azalea, is a striking native species. The fragrant flowers are 1 to 1.5 inches across, and come in shades of pink to white with usually no blotch. The stamens are quite long , usually twice as long as the tube.
Discovered by Mark Catesby about 1730, R. canescens is often confused with R. periclymenoides (R. nudiflorum ) but can be distinguished by the sticky glandular hairs on the tubes of the flowers and some other morphological characterics.
Although typically considered a southern species, R. canescens is a hardy shrub that deserves wider landscape use. The 4 to 5 foot plant makes a spectacular spring show since the flowers open before the leaves have expanded.
R. periclymenoides (synonymous with R. nudiflorum is the common Pinxterbloom Azalea found in the lower Appalacian Mountains, Piedmont and Coastal Plains from Massachusetts to north Georgia and Alabama. The white to pink flowers open in mid spring as the foliage is expanding, are they slightly fragrant. The blossoms measure approximately 1 to 1.5 inches across and the stamens are more than twice the length of the corolla tube.
Discovered by the Rev. John Banister and introduced to England in 1734, this species is often confused with R. canescens. In addition to differences in the natural range of the two species, R. periclymenoides can be distinguised by its flower tubes which are typically fuzzy or pubescent but do not have sticky glandular hairs on the back.
Rhododendron prinophyllum (synonymous with R. roseum can be found from southwestern Quebec, through New England and northern Ohio, to Appalacian Mountains at the higher elevations. The flowers are typically rose pink measuring 1.2 to 1.8 inches across and are very fragrant.
Assumed to be a form of R. periclymenoides (R. nudiflorum) since its first mention in 1787, it was first described as a distinct species in 1914 by Small but had been under cultivation as A. rosea in Europe before 1812. R. prinophyllum can be distinguised from periclymenoides by a number of characteristics including the fact that it is ususally deeper pink in color and with a strong cinnamon to clove fragrance. Also, the blossom it is more funnel shaped with comparatively short flower tube, and the pedicels (flower stalks) are longer than the other species.
R. prinophyllum is a wonderful landscape plant for north eastern gardens, but may be more difficult in the south because of summer heat.
Rhododendron vaseyi, the rare Pinkshell azalea, is one of the first species to bloom in the spring. Its delicate pink to white flowers are typically flat-faced, about 1.5 to 2.25 inches across, and have some prominent spotting in the throat.
Discovered by George Vasey in 1878, this native azalea has a relatively restricted natural habitat in four mountainous counties of North Carolina. Growing at elevations of 3000 to 5500 feet, plants can be seen in bloom along the Blue Ridge Parkway in early spring.
R. vaseyi makes an excellent garden plant, and can be purchased plants from number of commercial sources. Please, never take plants from the wild.
The Orange to Red Group Group
The “Orange Group” includes five species whose flowers can range from yellow, through gold, to deep orange or scarlet: R. austrinum, R. calendulaceum, R. cumberlandense, R. flammeum, and R. prunifolium.
Rhododendron austrinum is known as the Florida Azalea and blooms in early spring before as the leaves are beginning to expand. The fragrant blosoms come in shades of orange through gold and yellow, and measure approximately 1 to 1.5 inches across. This species has very long stamens and the tube of the flower is often flushed with red but there is no blotch.
Discovered by Dr. A. W. Chapman before 1865, R. austrinum is similar in many respects to R. canescens including the sticky glanular hairs on the flower tube, but differs in the color variations which are orange to yellow rather than pink to white.
R. austrinum makes an excellent landscape plant as well as a valuable hybridizing resource, especially in southern gardens where heat tolerance is important.
Rhododendron calendulaceum, also known as the Flame Azalea, is surely one of the most spectacular native shrubs of the Appalachian Mountains. The flowers are larger than most of the natives, measuring from 1.5 to 2.5 inches across, and come in a wide range of colors from clear yellow, through shades of orange, to brilliant red.First collected by A. Michaux in 1795 from the Blue Ridge Mountains of North Carolina, this species has a wide range of distribution from southern New York, Pennsylvania and Ohio as a northern limit, southward through the Appalacian mountains to northern Georgia. In late May and June, entire hillsides can be washed with brilliant color as these magnificent azaleas come into bloom.
R. calendulaceum is difficult to propagate by cuttings, but is easily raised from seed. Please leave the plants in the wild for others to enjoy, and purchase blooming-sized seedlings from specialty nurseries for garden use since young plants establish easlily in the garden. R. calendulaceum is a naturally occuring tetraploid, having twice the number of chromosomes in comparison to the other native species. Because of this fact, it does not hybridize easily with most of the other natives and even if a first generation cross is made, the resulting hybrids are often sterile.
Rhododendron cumberlandense (synonymous with R. bakeri ) is commonly known as the Cumberland Azalea. It has a relatively isolated natural range on the Cumberland Plateau in Kentucky south to Tennessee and the mountains of Georgia, Alabama, and North Carolina. The flowers are not large, about 1.5 to 1.75 inches across, and typically range from yellowish-orange to deep red. This species is sometimes difficult to distinguish from the larger flowered R. calendulaceum, but the blossoms generally appear several weeks later after the leaves have fully expanded and the undersides of the leaves are usually waxy white or bluish in color.
The species distinction for R. cumberlandense was first described by Lemon and McKay in 1937. This native azalea makes an excellent landscape plant in its own right, but it also hybridizes easily with many of the other species, producing beautiful hybrids in a broad range of colors. Many of the brightly colored forms in the hybrid swarm of native azaleas on Gregory Bald probably contain R. cumberlandense genes.
Rhododendron flammeum (synonymous with R. speciosum) is a southern native azalea commonly referred to as the Oconee Azalea. Its blossoms are approximately 1.2 to to 1.8 inches across and come is shades of yellowish orange, through orange to deep red. This species can be distinguished from the earlier blooming R. austrinum in that the flowers usually have a blotch, they are not fragrant, nor do they have sticky glandular hairs on the corolla tube.
Exact date of discovery for R. flammeum 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. This species is a heat tolerant shrub of the Piedmont region of Georgia and South Carolina, and holds much breeding potential where hot summer stress is a problem.
Rhododendron prunifolium, the Plum Leaf Azalea, is one of the latest native azaleas to bloom. The orange to vivid red flowers open in late summer and measure 1.5 to nearly 2 inches across. Flower buds for the next season are usually formed before the current season's blossoms open.
First collected by R.M. Harper in 1913, R. prunifolium has a very small natural distribution in southwestern Georgia and eastern Alabama. There are a number of nurseries that carry this excellent native azalea since it propagates readily by seeds or cuttings. Plants should be grown with afternoon shade to prolong the flowers during hot summer months. The author of this website has also painted a watercolor of Rhododendron prunifolium to accompany his study of this wonderful native azalea.
To read more about these plants, the following are recommended: