JARS v46n3 - Native Azaleas of Georgia

Native Azaleas of Georgia
Sandra McDonald
Hampton, Virginia

The native azaleas and their hybrids are becoming ever more popular in southeastern United States as well as in most other areas where they can be grown. The state of Georgia is one of our richest states in total number of species of deciduous azaleas native to it. There are some 13 species in the state. The Distribution of Vascular Flora of Georgia (Jones and Coile, 1988) shows some of the distribution of 12 species, and Fred Galle (1985) reports the additional species Rhododendron bakeri from several locations. The overlap in distribution of species is very great and overlap of blooming seasons also occurs, making interspecific hybrids and introgression frequent. (Interspecific hybrids result when two different species have been successfully crossed either in nature or by man. Introgression results when an interspecific hybrid back crosses with one of its parental species through a number of generations, resulting in plants that look mainly like the one species, but possess some genes of the other species.) This is apparently common in Georgia and makes determining the species of many of the natives a real challenge.

A brief overview of the Georgia native azalea species, their colors, general distributions and approximate bloom times will help in understanding and recognizing the species. More complete information on the native species can be found in Galle (1974, 1985) and other publications.

The earliest blooming native azalea species are the pure white to deep pink R. canescens and the golden yellow R. austrinum , which both bloom in late March and early April. Both are fragrant. R. canescens is found throughout Georgia; R. austrinum is confined primarily to the southwestern part of the state, but has been found in other locations.

In early to mid-April the yellow, salmon or strong pink R. flammeum (syn. speciosum ) is found blooming in a very broad band east to west across the state in the Piedmont region.

The white to deep violet and fragrant R. periclymenoides (syn. nudiflorum ) begins blooming in mid-April and is found in parts of northeast, west and central Georgia (Jones and Coile, 1988). The pink fragrant R. prinophyllum (syn. roseum ) blooms in April to May and though rare has been reported in a northeast county of Georgia (Jones and Coile, 1988).

Also in mid-April to May the rare and lovely fragrant white R. alabamense can be found blooming in many of the counties on the western border of the state and in west central Georgia. Blooming about the same time as R. alabamense in April and May is the fragrant white, sometimes flushed with red R. atlanticum . R. atlanticum is native to southeastern Georgia on the coastal plain which borders the Atlantic Ocean.

R. calendulaceum , the non-fragrant yellow to orange to red flame azalea, blooms in May in the upper Piedmont region of northwestern Georgia. Blooming season is somewhat later at high elevations.

The fragrant white R. viscosum in its various forms grows throughout the state and blooms mid-May to July. Non-fragrant bright orange to red R. bakeri blooms in mid to late June and early July and is native to northern Georgia, usually at high elevations. R. arborescens is a fragrant white species occasionally flushed pink or red, and often with prominent yellow blotch and conspicuous red style. The southern form blooms in July and occasionally into August (Galle, Native and Some Introduced Azaleas for Southern Gardens ), though in other areas other forms of this species bloom in late May and early June. R. arborescens is found in north Georgia and the lower Piedmont.

R. prunifolium , the plum-leaf azalea, blooming in July, August and occasionally into September is non-fragrant and orange to deep red. It is native to western and southwestern Georgia in several of the counties bordering Alabama.

R. serrulatum , the fragrant white hammock-sweet azalea,* blooms in late July, early August and some forms even into September. It grows on parts of the coastal plain in southeast to east central Georgia.

The wealth of azalea species in Georgia brought at least one member, and probably many more, into the American Rhododendron Society. This member is a long-time collector and admirer of native azalea species and hybrids, Earl Sommerville who lives in Marietta, Ga., north of Atlanta. Mr. Sommerville and I have corresponded by letter and telephone for several years, and I have a number of slides and photographs of his native azaleas as well as some of his plants. While living in Georgia in the early 1960s, he joined the American Rhododendron Society as an at-large member because there was no chapter nearby. He was transferred to the Azalea Chapter by the national secretary only a few years ago. He attended his first chapter meeting in December 1990 and entered his first flower show in spring 1991 at which time his six entries won three blue ribbons and one red ribbon.

Earl's collecting started over 30 years ago in 1961 when he collected his first "wild honeysuckle bush" from Allatoona Lake area in Cherokee County in northern Georgia. This lake was built in the 1940s in foothills of the Appalachian Mountains. The first plant collected appears to be a hybrid of R. bakeri and R. canescens , a dark red with gold flowered plant. A fine pink flowered hybrid of R. canescens and R. flammeum was also found at Allatoona Lake. On another occasion at Allatoona Lake a plant which appears to be a dwarf hybrid of R. calendulaceum and R. flammeum was found and after 25 years is about 20 inches tall and eight feet wide. These were found in what later was determined to be a population of five intermingled species ( R. bakeri , R. canescens , R. arborescens , R. calendulaceum and R. flammeum ) and some interspecific hybrids.

The plants were growing in red clay with a layer of woods loam a few inches thick over the clay and were in a good amount of sun since they were at the edge of the woods. Few plants, if any, are left in this area as the land has been developed and is now a housing subdivision.

In the mid 1960s, the acquisition of a boat expanded the collection area from Allatoona Lake to Lake Lanier in Dawson County in northern Georgia and Lake Hartwell in Hart County in northeastern Georgia on the border of Georgia and South Carolina. In springtime Earl roamed the lake banks tagging exceptional plants. In the fall he would return and collect the plants.

The soil at the north end of Lake Lanier is sand and red clay, and the area was in full sun at that time after a logging cut-over. It was a wilderness in private hands. Plants growing in sunny areas such as this would grow large in a very short time, as they thrive in the sun. The best time to find plants was during the blooming season about two years after a cut-over. Species he found growing in the vicinity of Lake Lanier were R. bakeri , R. canescens , R. arborescens , R. flammeum and R. calendulaceum .

The Lake Hartwell area was hilly and the soil was woods loam overlaying red clay. Here the native azalea plants were growing at the edge of the lake where they had at least half a day of sun. A beautiful large flowered pink plant (see photo), possibly a hybrid of some combination of R. canescens , R. prinophyllum and R. atlanticum , was found in the Lake Hartwell area of east Georgia. This area is now in government hands and collections can not be made there. R. calendulaceum was also in this area.

In the late 1960s and early 1970s Earl began combining scouting for deer with scouting for native azaleas during the spring blooming season and tagging exceptional plants. In the fall he would go back and combine deer hunting with plant collecting. On one scouting expedition in 1967 a large single stem white R. canescens was found in Dawson County in north central Georgia. The single stem was approximately two inches in diameter and was about six feet tall. The top of the plant resembled an open umbrella with a spread of 12 feet. It had to be a very old plant.

Plants in this collection that seem to get the most comments tend to be plants that are natural or man-made hybrids of the natives with bigger blooms than the species or plants with large ball type trusses. Several ball truss type R. flammeum plants (see cover photo), or possibly hybrids of R. flammeum were collected near Cochran in middle Georgia near the Ocmulgee River. This was land with scrubby growth that flooded frequently. It is now a managed hunt area and collections can no longer be made. There were three different ball truss plants collected from this area, varying from gold to gold with orange. R. austrinum has also been found in ball truss form near Cairo in the vicinity of the Ochlockonee River in south Georgia.

A very pale pink to white R. alabamense was found in Miller County in southwest Georgia (see photo). Also in this county near the town of Colquitt in a sandy area near a creek were some fine R. austrinum .

Many plants have been given to Earl by friends. One such plant is an eye catching pink azalea having pink and white striped buds, which may be a hybrid of R. viscosum and R. arborescens with possibly some R. prinophyllum (see photo). It comes into flower in mid-May and looks like peppermint-striped candy. The flowers are long lasting and gradually fade to lighter pink.

Many of his plants have large flowers and are hybrids of various native azaleas with the large flowered native R. calendulaceum .

Most, but not all of these plants were moved from his old home to his current home on Old Mountain Road at the base of historic Kennesaw Mountain in 1980. The two acre garden, due to its aspect, is protected from severe weather and contains about 3,000 plants ranging in age from young one-year-old plants to very old plants. About 300 plants are native azaleas, the others being lepidote and elepidote rhododendrons, evergreen azaleas and camellias. In addition to collected plants and many that were given to him by friends, he has many plants that were purchased from nurseries. The peak bloom time is usually about April 20 in Earl's garden.

Considering the wealth of species and hybrids of native azaleas in Georgia, one should be able to find a native azalea in bloom somewhere in Georgia from March through August or even into September, an intriguing thought for native azalea enthusiasts.

*Hammock - sweet azalea: R. serrulatum was given this common name because it grows on hammocks (or hummocks), fertile areas higher than its surroundings and characterized by deep humus-rich soil.

References
Jones, S.B., Jr. and Coile, N.C. (1988). The Distribution of the Vascular Flora of Georgia. Dept. Botany, U. of Georgia, Athens, GA.
Galle, F. C. Native and Some Introduced Azaleas for Southern Gardens - Kinds and Culture. Ida Cason Callaway Foundation, Pine Mountain, GA
Galle, F. C. (1974) Southern Living Azaleas . Oxmoor House, Inc. AL
Galle, F. C. (1985) Azaleas , pp 65-76. Timber Press. OR
Solymosy, S. (1976) A Treatise on Native Azaleas. Bull. of the Louisiana Society for Horticultural Research. Vol. IV, No. 2.

Sandra McDonald is a horticulturist, who works at Le-Mac Nurseries, Inc. (an azalea specialty wholesale nursery), is an active hybridizer, is editor of her chapter newsletter, Mid-Atlantic Rhododendron News and Notes, and occasionally contributed to the Journal. She is active in both the Middle Atlantic Chapter and the ARS national organization.