by Ken Gohring

By far the largest number of Rhododendron species is found in Asia. A few species are indigenous to Europe and its western border with Asia. North America has about 27 species of Rhododendron, with 9 being evergreen, 18 being deciduous and dropping their leaves every winter. In general, the deciduous rhododendrons are called azaleas, but they are classified botanically in the Rhododendron genus. Many of the Rhododendron natives can be found in the Southeast. These are described below.

Native Azaleas

In the spring of the year, Southerners cannot help but observe Nature in her glory. It is that time of year when most plants come alive and show their beauty with lovely flowers. In north central Georgia, where I reside, some of the most beautiful flowers are native azaleas. I have admired these azaleas since I became a resident of Georgia years ago. While not as prevalent in residential landscapes as evergreen azaleas, the natural areas of Georgia and most of the South are home to numerous native azaleas, truly some of Nature’s finest. 

While I do not consider myself an authority on native azaleas, I have had extensive exposure to them and would like to share some of my experience and study. The number of native azaleas found in the United States is a changing number, primarily for two reasons: botanists keep revising classifications, and new species are still being discovered. There are at least 16 native azaleas found in the lower 48 states. At least 12 of these are native to Georgia, more than any other state. 

Rhododendron canescens Piedmont Azalea

By far, the most common azalea in the South is Rhododendron canescens, the Piedmont azalea. Found from North Carolina to Florida and west to Texas, it is frequently referred to as “bush honeysuckle.” While many native azaleas are known by that designation, this species in particular deserves it. It is fragrant, and the blooms are similar to those of wild honeysuckles. The blooms range in color from pure white to light pink to bright pink. It grows up to 15 feet tall and is usually found close to moist areas along creeks and gullies. Extensive colonies can be found throughout Georgia. 

Many of these plants do not bloom, for in order to set buds, this species requires more light than some of the other native azaleas. There are numerous R. canescens in my neighborhood west of Marietta, GA. Most of these plants seldom bloom, and when they do, the blossoms are in the very top of the plants. In areas of my neighborhood where homes have been built, some of the R. canescens have been retained, while trees and other shrubs have been removed. These azaleas put on a beautiful show in the spring, covered with fragrant pink blooms. Some of these plants are almost in full sun and most have developed a more pleasing, rounder, more compact shape than those growing in full shade. 

Rhododendron flammeum Oconee Azalea

Another desirable species is the Oconee azalea (R. flammeum). It was called R. speciosum for many years, and it is still referred to by that name. This is a beautiful azalea, found mostly in a band across middle Georgia but also in South Carolina. The primary distribution areas are along the Flint and Savannah River drainage areas. Its bloom color ranges from yellow to orange to red and sometimes pink; however, orange is the most predominant color. It is considered one of the two best red native azaleas. The Oconee azalea is usually found on hillsides and will tolerate drier conditions than R. canescens. It also blooms better in shade. One notable characteristic is that it blooms at an early stage. In one area, I found one that was only about 12 to 14 inches tall that had about 15 bloom buds on it. R. flammeum is not fragrant and is rarely stoloniferous. It does not grow as tall as other native azaleas, usually reaching a maximum height of 7 to 8 feet. 

On one occasion at one of Prof. George Sanko’s luncheon meetings at Perimeter College, Ernest Koone III, owner of Lazy K Nursery, recalled seeing large populations of R. flammeum in the areas northwest and west of Atlanta. Many of these populations were wiped out as Atlanta spread. Fred Galle, former curator of gardens at Callaway Gardens and author of the prize-winning book Azaleas, recalled in one of his writings that an area of 1,000 acres west of Atlanta was clear-cut and bulldozed. Callaway Gardens was alerted and was able to collect over 500 dormant plants from the area. However, the site had never been explored in the flowering season. One Atlanta botanist was able to collect 12 dormant plants from the area, and she planted them in her garden. One of these plants exhibited split petals and was later registered as the cultivar ‘Chattahoochee’. The other plants had typical pink to yellowish pink flowers of hybrid origin, most likely crosses of R. canescens and R. flammeum, though other natives possibly contributed to the crosses. 

In Cherokee County, both R. canescens and R. flammeum are found. One spring I observed R. canescens blooming first, predominately pink or light pink, then the R. flammeum and hybrids of the two bloomed. The R. flammeum blossoms covered the color range discussed previously. The hybrids were outstanding as well. Some were clear white with a single yellow petal, but most were pink with yellow coloration, like those referenced by Galle on the site west of Atlanta. Most of these hybrids were fragrant. Another site in south Cobb County along Nickajack Creek has R. flammeum azaleas, some of which are a beautiful red.

Rhododendron calendulaceum Flame Azalea

Another azalea found in the Atlanta metro area is R. calendulaceum or flame azalea. In his Azaleas book, Galle says that the famous plant explorer William Bartram gave this description:

 “...this most celebrated species of azalea, as being expressive of the appearance of its flowers which are in general of the colour of the finest read lead [sic], orange, and bright gold, as well as yellow and cream colour; these various splendid colours are not only in separate plants, but frequently all the varieties and shades are seen in separate branches on the same plants; and the clusters of the blossoms cover the shrub in such incredible profusion on the hillsides, that suddenly opening to view from dark shades, we are alarmed with apprehension of the hill being set on fire. This is certainly the most gay and brilliant flowering shrub yet known.”

Botanists have discovered that R. calendulaceum is a tetraploid, whereas most other native azaleas are diploids. This chromosomal difference is likely a factor in R. calendulaceum sporting the largest flowers of the native azaleas. The plant is a native of the Appalachian Mountains and foothills from Pennsylvania to Georgia. As with R. flammeum, this species is found growing in drier areas. I have seen it growing in north Fulton County near Alpharetta, GA not far from the Chattahoochee River. Nice orange plants were found blooming in mid-May, and later yellow forms bloomed.

Rhododendron periclymenoides Pinxterbloom

On one occasion, in the company of Joe Coleman, a recognized authority on native azaleas, I joined some master gardeners in Gordon County to observe some native azaleas at a construction site. We found several native azaleas growing on a hillside. Joe indicated that they were R. periclymenoides (pinxterbloom azalea). Distribution maps of this species show that its range in Georgia is in the northern part of the state. For hundreds of years this species was known as R. nudiflorum but about 50 years ago, its name was changed. As its previous name suggests, the plant’s flowers appear before the leaves emerge (as is the case with several other native azaleas). The species is often confused with R. canescens. It has the same color range, is sometimes fragrant, and has long stamens like R. canescens. Both species are widely distributed throughout the eastern part of the country, with the pinxterbloom being the more northern species. This species can be distinguished when in bloom, because R. canescens usually has sticky glandular hairs on the outside of its floral tube, while R. periclymenoides has plain fuzzy hairs without the sticky glands. 

Rhododendron arborescens Sweet Azalea

R. arborescens is another species of azalea found in Georgia, and I have seen it growing in Cherokee County. Its range is from Alabama to New York. It has been found farther south in the area of Callaway Gardens. It is usually white to blush-pink and is distinguished by its red stamens. Occasionally one will find it with a yellow blotch or a yellow flush. Normally it is found near flowing streams at water's edge and moist areas. It normally blooms in late May and June, but there is a Georgia form that blooms in August. R. arborescens is frequently called the smooth azalea because of its smooth stems and is also called the sweet azalea because of its marvelous fragrance, probably the strongest fragrance of all native azaleas.

Rhododendron prunifolium Plumleaf Azalea

Most Georgia gardeners have probably heard of the plumleaf azalea (R. prunifolium) due to the popularity it has achieved through Callaway Gardens. In fact, it is said that Callaway Gardens was founded to provide a home for this beautiful species. The flowers range from orange to red. It is a late bloomer, sometimes blooming as late as September. Next season’s buds usually form before the current season’s bloom. This species is found primarily in Georgia, with some native plants found in Alabama. Providence Canyon, a Georgia State Park south of Columbus, is a prime location to see this species in its natural habitat. 

Rhododendron atlanticum Coastal Azalea

The coastal azalea (R. atlanticum) is a species that has found favor as a landscape plant because of its relatively small size and growth habit. It is usually an understory plant, seldom growing over 3 feet tall. This tetraploid azalea is very stoloniferous and easy to propagate. In nature, it is found along the eastern coast of the United States in pine barrens and abandoned fields. In Georgia, it is found in the coastal areas around Savannah. It usually has white flowers, often with pink on the outer edges. Some have a yellow blotch of color on one of the petals. 

Rhododendron alabamense Alabama Azalea

Another fine landscape azalea is the Alabama azalea (R. alabamense), and it is one of my favorites. There are two 5-foot specimens growing in my yard. One has the traditional white bloom with a yellow blotch on the petals. The other is yellow with a darker blotch. Probably, the plant with the yellow blooms is a cross with the species R. austrinum, because generally both species bloom about the same time. I think the fragrance of the Alabama azalea is the most outstanding and distinctive of all native azaleas. Another attractive feature of this species is its relatively low growth habit. This species is found primarily in Alabama, but plants have been found in Georgia, Florida, Tennessee, and supposedly, South Carolina. (See below for more about the South Carolina occurrences.)

Rhododendron viscosum Swamp Azalea

The most variable of all native azaleas is the swamp azalea (R. viscosum). In the past, plants called R. serrulatum (hammocksweet), R. oblongifolium (Texas azalea), and R. coryi were recognized as separate species, but now all have been classified as various forms of R. viscosum. The flowers of all are usually white, sometimes tinged with pink. They have a sweet, musky fragrance and have no blotch on the petals. I personally have R. serrulatum and R. viscosum growing fairly close to each other, and the R. serrulatum is three times as tall as the R. viscosum. In its various forms, the viscosum complex of azaleas is found from New England to Florida and west to Missouri, Arkansas, Oklahoma, and Texas.

Rhododendron cumberlandense Cumberland Azalea

The Cumberland azalea (R. cumberlandense) is another outstanding native. The natural distribution area for this species includes north Georgia, with outstanding populations also existing in the Cumberland Plateau in Kentucky and Tennessee, hence the name cumberlandense. However, many azalea people still refer to this species as R. bakeri, after Professor Wilford Baker of Emory University. Its color range is similar to R. calendulaceum, perhaps more red, however, the blooms are generally smaller and the plant has a smaller structure. One year, I observed R. cumberlandense in bloom in Chattanooga the third week of May, about two weeks after seeing R. calendulaceum in bloom in north Georgia. 

Rhododendron austrinum Florida Flame Azalea

The Florida flame azalea (R. austrinum) is a favorite of many azalea enthusiasts. It is another of the tetraploid azaleas. It grows naturally in northern Florida, and adjoining areas in Georgia, Alabama, and Mississippi. It is said that the late Azalea Chapter member Lewis Shortt found this species in the Atlanta area along the Chattahoochee River. The Florida flame azalea also does well farther north. It is fragrant, but, in my opinion, not as strong or as pleasant as R. canescens. The color is usually yellow, with some orange and red cultivars identified. The red cultivars could be natural hybrids. An outstanding natural hybrid is 'Millie Mac', an attractive white and yellow bicolor. 

Rhododendron vaseyi Pinkshell Azalea

The pinkshell azalea (R. vaseyi) is confined to a few mountainous areas of western North Carolina. At one time, it was thought to grow on Rabun Bald in northeast Georgia. However, several exploratory field trips did not result in any confirmation. The plant is most commonly found at elevations 3000 to 5500 feet above sea level, but it has adapted to lower elevations. In several ways, this plant is different from most native azaleas. It is more bell shaped than tubular and has most often 7 (5-7) stamens instead of the usual 5 for deciduous azaleas. Vaseyi does not hybridize with other azaleas, and its leaves are also distinctive, being somewhat fleshier than those of other azaleas. It is extremely difficult to propagate from cuttings, but since it does not cross with other azaleas, it can be propagated by seed.

Rhododendron prinophyllum Roseshell Azalea

Another attractive native azalea, not known to grow in the wild in Georgia, is the roseshell azalea (R. prinophyllum, formerly R. roseum). I have seen the plant growing well at the Reflection Riding Arboretum in Chattanooga, TN but it is said not to do very well in Georgia because of the heat. This species is widespread north and west of Georgia. It is found from Canada to North Carolina, primarily at higher elevations, and also in disjunct populations in Missouri and Arkansas. The roseshell azalea is very fragrant and is usually a clear pink in color. I have a friend who tells of finding this species in Arkansas. The plant was found by noticing its pleasant fragrance before actually seeing the plant. It is a rather late bloomer compared to the other pink azaleas, R. canescens and R. periclymenoides. 

Rhododendron eastmanii May White Azalea

A few years ago, those who have an affinity for native azaleas were excited about the classification of a native azalea found only in the state of South Carolina, thus far. The person primarily responsible for the R. eastmanii classification is Mike Creel, a retired South Carolina Department of Natural Resources employee. Back in the eighties, Charles Eastman visited the South Carolina DNR, bringing an impressive group of native azaleas of diverse colors. This started a friendship that lead to frequent exploration of South Carolina natural areas in search of native azaleas. Eastman showed Creel an attractive white azalea that he had found, and the two visited the source site and another. After a period of time, Creel came to the conclusion that his first thoughts, that the azalea was R. viscosum, a highly variable species, were incorrect. He was led by a DNR associate to Dr. Kathleen Kron, a respected botanist at Wake Forest University. Together the two worked over a period of several years and in a paper published in 1999 concluded that the azalea was previously unregistered and was a distinct species. They proposed the name R. eastmanii in honor of Mr. Eastman. 

For years, it was thought that the attractive species, R. alabamense, grew in South Carolina. It was so indicated in the writings of the noted native azalea authority, Fred Galle, long time horticulturist at Callaway Gardens. In addition, there is a reference, Radford, et al, Manual of the Vascular Flora of the Carolinas that cites an occurrence in Calhoun County, SC. However, the Radford reference expresses a lack of “distinctiveness” of the species.

The species R. eastmanii is similar in many ways to R. alabamense, and some thought the new species was R. alabamense. Both species are white with a yellow blotch and both have very pleasant fragrances. However, there are several differences. R. eastmanii usually blooms in May, whereas R. alabamense is an earlier bloomer, with blooms usually appearing in April. At the time of the Creel/Kron study, no other native azalea was known to bloom in May at South Carolina’s latitude. R. eastmanii has a common name of May White because of its May bloom time. The blooms of R. alabamense usually occur before the plants leaves fully expand, while R. eastmanii blooms occur after the leaves are full. In addition, the physical characteristics of the R. eastmanii bud are unique with features not shared by any other native azalea. 

Perhaps the most thorough work on the culture of R. eastmanii has been conducted by Dr. Charles Horn of Newberry College, Newberry, SC. Kron and Creel’s work in formally recognizing R. eastmanii took place in 1999. In the years 2000 to 2003, Dr. Horn conducted an extensive study of the species. Some of his findings:

1) Twenty-three sites were documented in 11 South Carolina counties. These sites had varying numbers of specimens, ranging from five plants to over 300.

2) The sites are located close to streams, usually on north or northeast facing slopes, composed of oaks, hickories and other deciduous trees. The slopes in many cases were quite steep with the plants most commonly found half way up the slope.

3) The soil acidity of the sites range from 4.8 to 6.8 pH. Originally, Creel and Kron indicated that the species appeared to prefer neutral soil. Dr. Horn, based on his measurements, concluded that the species prefers slightly acid to circumneutral soils.

4) The species is not so rare that it is in danger of becoming extinct.

The Horn research indicates that the species is primarily located in the watershed of the Broad and Congaree Rivers with 22 of the 23 documented sites in this area. Most of the sites were on bluffs overlooking the Congaree River or in the case of Piedmont areas, at the headwaters of streams that flow into the Broad-Congaree watershed. However one such stream flows into the Savannah River. 

One wonders whether the species is confined entirely to South Carolina. Dr. Horn concludes that more study is needed to determine if the species is found in Georgia, North Carolina or elsewhere, to get a complete picture of the species’ distribution. To this end, efforts to locate the species present a challenge and should be guided by Dr. Horn’s studies, with special attention to characteristics of the locales where the species was found.

Rhododendron colemanii Red Hills Azalea

Another exciting happening in the world of native azaleas is the recent recognition of another new species named in honor of S. D. Coleman, a Georgia nurseryman, who did extensive study of native azaleas in the period of the 1940s to the 1960s. Coleman had a nursery in Fort Gaines, GA, about 70 miles south of Columbus on the Chattahoochee River. For years Mr. Coleman collected and propagated native azaleas found in the general area of where he lived. One of the plants that he sold, called ’May Pink’ bloomed in May and was generally pink in color. It is the particular azalea that has become recognized as R. colemanii, with a common name of ‘Red Hills’ azalea.

The intriguing story of how R. colemanii became recognized was related in the Journal of the American Rhododendron Society (ARS) in an article by Dr. Ron Miller and Steve Yeatts, a native of Athens, who has been an Azalea Chapter member for several years. For some years Steve has been involved in the study of native plants, in particular native azaleas and trilliums. 

The activities that led to the species formal recognition in 2008 took place over a period of several years. Most likely, Mr. Coleman was the first to observe the species in the wild, but others such as Dr. John Thornton, a Louisiana rhododendron authority, collected and propagated the species. Not aware that it was a distinct species, Thornton collected cuttings of what he thought was R. alabamense from a site near Phoenix City, AL and later Monroeville, AL. Clippings of these plants were examined by an azalea authority who classified them as R. alabamense. Thornton propagated the plants and sold thousands of them through his nursery to people all over the country. Later the work of the group that pursued the recognition of the species clearly identified these plants as Red Hills azaleas

Prior to Thornton’s collection, Dr. R. O. Smitherman, an Auburn University professor found a population of what is now recognized as R. colemanii in Clarke County, AL. These plants were both pink and white. He started a breeding program with these plants and over time observed that the plants had the same characteristics of some of the ‘May Pink’ azaleas that he had acquired from S. D. Coleman. 

Another person involved in the story is Dr. Alvin Diamond of Troy State University, who as a graduate student at Auburn observed the species in his studies of the Red Hills salamander. He observed the plants at several sites and collected herbarium samples. He found the more common white blooming plants as well as pink and yellow forms. Originally, he thought the plants were hybrids but later became convinced that his finds represented a new species.

In the late nineties, Steve Yeatts and his associate, Bob Stevens, went to a site in south Alabama looking for a population of R. alabamense. They were guided by a herbarium sample at the University of Georgia that listed the site. They took cuttings and later had a blooming plant that just did not look like the typical R. alabamense. Their interest and efforts continued, first thinking the plant might be the recently recognized R. eastmanii. Their efforts continued with establishing contact with Dr. Thornton. They visited the site where Thornton collected earlier. They also went to the site discovered by Smitherman. They worked persistently to obtain a proper classification of the azaleas that they had encountered. Yeatts met Dr. Ron Miller, a retired English professor, through John Thornton. Miller possessed the same inquiring mind and zeal as Yeatts.

For a period of time their joint efforts included the study of native populations of azaleas in southern Alabama and Georgia that exhibited features not characteristic of R. alabamense. They learned the characteristics and how they differed from R. alabamense. The differences that they noticed included the following:

a) a range of color that included pink, white and yellow.

b) stoloniferous character. 

c) time of bloom.

d) character of new growth.

e) qualities of bloom buds.

f) size of adult plants.

g) area where plants were found (Red Hills)

After several seasons of visiting south Alabama and southwest Georgia sites, the group involved Azalea Chapter member, Dr. Clarence Towe. Towe was skeptical at first but proceeded to involve prominent botanists at the University of Washington and North Carolina State University. The analysis and study conducted at these universities resulted in a definite recognition of the species. In fact, the work concluded that the new species was a tetraploid as opposed to the more common diploid chromosome structure found in most native azaleas, including R. alabamense.

The recognition of these two new species, R. eastmanii and R. colemanii, was the result of dedicated plant scientists. Their efforts have resulted in clearer knowledge of native azaleas. These persons are to be commended for their diligent efforts in providing better classification of native azaleas. It is interesting that neither of these species is new. They have been around for years, just not classified as distinct species. This situation is most likely caused by the fact that azaleas cross-pollinate and hybrids can exhibit characters from both parents. This cross-pollination occurs usually between species that bloom at the same time, but some point out that cross-pollination can occur between species that normally bloom at significantly different times. On occasion, weather conditions cause species to delay their bloom time resulting in opportunities for cross-pollination of species which normally bloom at distinctly different times. Many hybrid azaleas are found in the Atlanta area, but most of these are crosses of R. canescens and R. flammeum, the two most common natives in the Atlanta area, whose bloom periods overlap.

Both of these “new” azaleas promise to be good plants for native gardens. Both bloom after the earliest blooming natives. Both are fragrant and appear to be easily propagated with stem cuttings. Their landscape use may be dictated by their growth structure. Because adult plants reach 15 feet or more, they should be located appropriately.

Tables summarizing native azalea features

Other Rhododendrons

Rhododendrons have been called the King of Shrubs for various reasons, but most likely, because of the species with luxuriant evergreen foliage and flower forms that rival those of any plant species. In fact, many years ago, Endi Ostbo, a nurseryman whose nursery was named King of Shrubs, introduced a rhododendron cultivar by that same name. Mr. Ostbo’s introduction was an orange-flowering plant of Asiatic origin. Many of the commercial rhododendrons available in the nursery trade are of Asiatic origin, but there are American native rhododendrons whose beauty rivals any of the Asian species.

Rhododendrons are members of the genus Rhododendron, a member of the heath family (Ericaceae), which also includes heathers, mountain laurels, and blueberries. Rhododendron is a word of Greek origin, with rhodos meaning “rose” and dendron indicating “tree.” Rhododendrons are found on all continents with the exception of South America, Antarctica, and Africa, with Southeast Asia being the center of the majority of species.

In general, rhododendrons are characterized as having large, shiny, evergreen leaves and clusters of large blooms that range in color from white to pink to purple. (R. minus is somewhat uncharacteristic in that it is relatively small and has small leaves.) With their large evergreen eaves, they are plants for all seasons with a special reward in the spring when their showy flowers are borne. Most cultivated rhododendrons are hybrids that include heritage from both Asian and American species. The American rhododendron parentage is especially useful for capturing some of their desirable growth habits, such as cold tolerance (and also heat tolerance) and plant form. 

In the southeastern United States there are three species of evergreen rhododendron. These are not to be confused with the more than a dozen species in the Rhododendron genus that are native azaleas, discussed above, and readily distinguished by their smaller, deciduous leaves and flower forms. In practice, while all azaleas are technically classified in the Rhododendron genus, the term “rhododendron” is usually used to designate broadleaf evergreen rhododendrons. Native evergreen broadleaf rhododendrons are found in the northeast and in the western areas, but only the southeastern species are considered here.

While it is said that there are three species of evergreen rhododendron native to the Southeast, there is some difference of opinion in the designation of one species known as R. minus. The other two species are R. maximum and R. catawbiense.

Rhododendron maximum Great Laurel 

R. maximum, known as great laurel or rosebay, is well named as it is the largest of the southern rhododendrons, typically growing 6 to 10 feet tall and sometimes reaching 25 feet or more. I have not seen the species growing naturally in the Atlanta area, but have heard of it growing in the wild in counties just north of the city. I have also heard reports of it growing locally, but in several cases, the individuals were mistakenly referring to populations of mountain laurel (Kalmia latifolia). 

My first exposure to the Rhododendron species was in my younger days, when I fished the trout streams of north Georgia. There, dense thickets of rhododendron line the streams making it impossible to travel through them while fishing. Instead, one has to wade in the streams to fish. North Georgia streams are frequently lined with R. maximum, but the species grows in other moist areas, usually in the understory of forest trees. The species’ spreading growth pattern is somewhat irregular, with a loose, multi-stemmed nature. Its texture is described as “coarse,” probably because of its leathery, bright green leaves that grow up to 8 inches in length, with the leaves of some specimens reaching to 12 inches. The undersides of the leaves are sometimes green but frequently are light brown in color.

R. maximum is truly an understory plant that does poorly without overhead protection. Its natural range extends from Georgia north to Nova Scotia and west to Alabama and parts of Ohio. Its blooms, most often white with pink tinges, form in small trusses. Other color forms have been found in the wild. The individual flowers are up to 1½ inches across with up to 25 individual flowers in each truss. It is late blooming, usually flowering in June after hybrid rhododendrons have bloomed. The plant’s fruits are unattractive seedpods that contain numerous small seeds. 

I have had R. maximum in my garden for several years. The first plants that I had grew to about 5 feet and bloomed well. Now living in a different area, the plant that I have is about 4 feet tall but has yet to bloom. Landscape usage of R. maximum is restricted to shady areas, and because of its potential size, it is limited to the edge of wooded areas. It does not survive in areas where its roots are not well drained. R. maximum is easily grown from seed but is somewhat difficult from cuttings. 

R. maximum is not often offered by commercial plant vendors. There are several cultivars, varieties, and hybrids available that have features of interest, though these may be difficult to find due to propagation and culture characteristics. Var. album features white flowers, while var. purpureum has darker flowers with dark pink to purple coloration. A more compact form known as var. leachii has smaller leaves with wavy margins and its blooms are typically pink-white. Many hybrids have been bred incorporating R. maximum. They include ‘Midsummer’, which has pink blooms with a gold colored throat; ‘Pride’s Pink’, an upright, spreading form and large pink blooms; ‘Short off’, a compact form growing to only 4 feet tall over a period of 20 years; and ‘Mount Mitchell’, which has the ‘Red Max’ form (described below) in its heritage. 

The most interesting cultivar, in my opinion, is a specimen called ‘Red Max’. In the early 1930s during the depression, when the construction of the Blue Ridge Parkway was taking place near Mount Mitchell, a scout for the construction crew came upon a population of 15 to 20 R. maximum with an unusual red coloration. He took a collection of cuttings and sent them to an ARS member who shared them with others. This plant’s blooms are indeed red. In addition to the bloom, many parts of the plant, including the buds and leaf veins, are red. ‘Red Max’ has become almost legendary, with extensive study conducted concerning its features and use in breeding other forms. The plant has an unstable nature with wide variety in flower color. In fact, the plant and its offspring frequently have blooms that differ in coloration from limb to limb and from season to season on the same plant. In addition, there are differences in color when the plant is grown at lower elevations. 

I have an acquaintance that lives in North Carolina and is an active member of the ARS. His chapter of the organization has made a trip every year since 1990 to study the original wild ‘Red Max’ population. His interest in the plant includes following the growth and blooming habits of seedlings and cuttings at various locations. In his garden, he once observed that his specimen had seven trusses. Of these, two were the normal R. maximum white, two were solid red, and the remainder was picotee forms with a red center and white edges. Azalea Chapter member Joe Coleman has had similar experience with the fairly large specimen that he has in his garden in Lithonia. Dr. August Kehr wrote an authoritative article on 'Red Max', which appeared in the ARS Journal. http://scholar.lib.vt.edu/ejournals/JARS/v48n1/v48n1-kehr.htm.

For those who appreciate a vigorous, shade-loving plant, R. maximum would be a welcome addition to the native plant garden.

Rhododendron catawbiense Catawba Rhododendron 

If one has not had the experience of traveling to Roan Mountain on the Tennessee-North Carolina border in mid to late June to view the massive collection of R. catawbiense in bloom, then one of the most beautiful experiences of nature has been missed. These beautiful native rhododendrons are also found extensively along the Blue Ridge Parkway, with Craggy Gardens being a particular highlight. The range of this species extends into Georgia with some being found as far south as Cherokee County. A particularly fine location to see the species is Cloudland Canyon in northwest Georgia. The species’ northern range extends into Virginia, West Virginia, and Kentucky, and it also grows in northeast Alabama. 

The Catawba rhododendron grows from 6 to 12 feet tall and has dark evergreen leaves from 3 to 5 inches long. Its leaves are readily distinguished from those of R. maximum. The leaf of R. catawbiense is more rounded and has a rounded form at the base, while the leaf of R. maximum is larger and forms an acute angle at the base where it intersects the stem. The blooms of R. catawbiense occur in clusters up to 6 inches in diameter with five to ten individual 2½-inch flowers, which are funnel shaped. The time of bloom varies by elevation, with lowland forms blooming in mid-May. The plant’s rounded to upright forms are more pleasing than R. maximum. Unlike R. maximum, the species flourishes in open sunlight at higher elevations. However, at lower elevations it is best grown in some shade.

There is wide color variation in the blooms of R. catawbiense. Those growing on Roan Mountain are primarily magenta in color. Other cultivars have white blooms, and some red forms have also been discovered. One particularly good white form is var. album.

The specific epithet catawbiense comes from the word Catawba, which is the name of a river in North Carolina, named for a tribe of Native Americans. The species was first discovered along the Catawba River in 1809. Many rhododendron fanciers stress that the lowland R. catawbiense var. insularis is more desirable for gardens not located at higher altitudes. 

When used in the native garden, R. catawbiense can be used as a specimen, massed in a group, or incorporated into a border. While it is said that it can be grown in full sun, it is best to use it in a woodland setting where it is in a partially shaded area. 

R. catawbiense has been used extensively by rhododendron breeders in efforts to develop cultivars capable of withstanding diverse climatic conditions, in particular cold climates. The large array of various cultivars includes forms, varieties, and hybrids. Some of the more popular are the following: 

• Var. compactum is a compact form found on a mountaintop that only grows to 3 feet.

• ‘Catalgla’ is a cold-hardy selection of var. album. (It should be noted that there is also a hybrid with the name ‘Album’.)

• ‘English Roseum’ is a vigorous, compact grower, most likely a hybrid.

• ‘Roseum Elegans’ has small rose-like flowers and strong resistance to both heat and cold. This is likely a hybrid. In general, rhododendrons are not easy to grow in Atlanta. One Atlanta authority says to try any form that has roseum in its name.

• ‘Lee’s Dark Purple’ is a deep purple hybrid.

• ‘Scintillation’ is a hybrid particularly popular in the Atlanta area.

Truly, catawbiense is one of Nature’s outstanding plants. Its widespread use as a breeding parent is testimony to its character. Like R. maximum, it should not be planted in areas of poor drainage. It should be considered by those who like plants with large, spectacular flowers. 

Rhododendron minus Carolina Rhododendron 

There are diverse opinions regarding the classification of a group of rhododendrons known usually by the designation R. minus. Most of these plants have similarities that might lead one to group them into a single classification. However, there are differences in physical characteristics that lead some to designate the plants as separate species. While the matter of whether the different forms are distinct species is important to those concerned with such matters, the average plant enthusiast is more likely interested in the individual characteristics of the distinct forms. For some time, the three distinct forms of these plants have been classified as varieties of one species. However, some have proposed revising the existing taxonomy to specify multiple distinct species. In this article all forms will be considered as a single species. 

R. minus grows naturally in the southeastern states of the country. It was first discovered by the French botanist André Michaux. During the 18th century, he collected plants in the Appalachian Mountains for the French government, describing some 283 species in a period of 11 years of exploration. The flowers of R. minus range in color from white to pink and other variations. It is a relatively low-growing plant; however, it sometimes reaches 25 to 30 feet in height. Its physical form, while compact, is open and straggly. The evergreen leaves vary from 2 to 4½ inches in length and up to 2½ inches wide. The specific epithet minus most likely comes from a comparison of its leaves and structure with R. maximum.

R. minus var. minus (also known as R. carolinianum)

This variety is found in the Carolinas, Georgia, and Alabama. While frequently growing in a loose form in the wild, some selections feature habits that are more pleasing. The leaves are generally elliptical in shape with dense scales on the underside. The leaf tips are variable, with both acute and obtuse forms frequently occurring and with the whole leaf exhibiting both flat and inward curving features. The flowers normally appear on the terminal ends of branches; however, some selections feature blooms along the outer leaf nodes as well.

R. minus var. minus is now recognized as having two distinct forms. Georgia nurseryman S.D. Coleman, one of the pioneers in the promotion of appreciation of southern native azaleas, proposed the recognition of a form now known as the Chattahoochee group of R. minus. This form is found primarily in the basin area of the Chattahoochee River in Georgia and Alabama. Its flowers are said to be more attractive than the plants found primarily in North Carolina, which are referred to as the Carolinianum group. 

The Chattahoochee group was studied in significant detail in the early 1990s in a study sponsored by the ARS. This study documented the location of populations of this form in several counties in Georgia and Alabama. Their work also included the introduction of some select forms found during the study. Some of these are Georgia natives, including ‘Kolomoki’ and ‘Fort Gaines’, found near the Kolomoki Creek area in Early County. This study was documented in the ARS’s quarterly Journal http://scholar.lib.vt.edu/ejournals/JARS/v48n1/v48n1-thornton.htm. That article includes a map showing the counties in both states where the variety has been found. 

A few years ago on a trip to Mike Creel's home in South Carolina, I met Dr. John Thornton, one of the authors of this article. He and an associate, Dr. Ron Miller, were continuing the study of R. minus, traversing around several southeastern states. They were towing a small motor boat behind their pickup and indicated that the best way to look for native plants was from lakes and streams. He said that he had recently found a new yellow form of R. minus. Other selections that have found favor among gardeners are two white-blooming selections, ‘Gables Form’ and ‘White Gem’. An older yellow form, ‘Burn’s Yellow’, and two pink forms, ‘Helen Cascio’ and ‘Fairhaven’, are available commercially. 

R. minus has been used extensively in breeding improved rhododendron forms. Perhaps the most widely known are the PJM selections developed by the Weston Nursery. R. minus is easily propagated from both cuttings and seeds.

R. minus var. chapmanii Chapman Rhododendron

This variety of R. minus occurs naturally in three locations in northern Florida. Two of these sites are privately owned, and the other is a National Guard installation. The largest of these sites has about 500 plants. Clear-cutting in the 1970s severely affected the number of plants. However, in some instances, the cutting reinvigorated plants after a burn and the planting of pine trees. It is considered an endangered plant and is protected. It is geographically isolated from R. minus var. minus, but one population grows only 70 miles from a population of Chattahoochee form plants. The leaf is somewhat smaller than that of the minus variety. It has rounded tips, appears more oval in shape, and is often curled. Leaves exhibit an aromatic quality when crushed. 

R. minus var. chapmanii grows to 6 feet in height with a spreading nature, the result of extensive layering of the limbs rather than extension of stolons. This quality may have prevented its extinction. It lacks significant reproduction in the wild from seeds, probably because of the dry environment in which it frequently grows. Var. chapmanii blooms earlier than var. minus because of its more southerly location. When grown at the same latitude with var. minus, chapmanii blooms two weeks later than the Carolinianum forms but two weeks before the Chattahoochee forms. This results in a six-plus week range in bloom, with the first blooms occurring in April and May. 

Azalea Chapter member, Charles Hunter has conducted significant research of R. minus var. chapmanii. That work was summarized in an ARS Journal article. http://scholar.lib.vt.edu/ejournals/JARS/v45n3/v45n3-hunter.htm

As with the minus variety, var. chapmanii has been used in breeding practices to achieve heat tolerance in the offspring. I have two April-blooming specimens of var. chapmanii in my garden. They appear to be doing well. One of the plants has leaves about 2½ inches in length, while the other’s leaves are only a little over an inch long. They are not outstanding landscape plants but do provide interesting variety in the garden and will successfully stand hot summers in the South. 

More recently Ron Miller [1] has extensively analyzed the minus complex and concludes that there may be three species and several varieties involved. In a 2013 article,  Miller suggests that R. minus should have two varieties: R. minus var. minus and R. minus var. chapmanii. That carolinianum should be a separate species (R. carolinianum) with two varieties, a Linville “carolinianum” and a Pisgah “album.” Further, Miller believes the high elevation form first noticed by S. D. Coleman and later by Don Hyatt and others around Newfound Gap should be a separate species, which has casually been called "smokianum".

References

[1] Miller, Ron. (2013, Spring). “Stalking the wild lepidotes: Rhododendron minus reconsidered.” Journal American Rhododendron Society, 67 (2): 63-68, 78-83.

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