JARS v58n4 - Deciduous Azaleas: New Species and Hybrid Selections

Deciduous Azaleas: New Species and Hybrid Selections
L. Clarence Towe
Walhalla, South Carolina

As deciduous azaleas continue to grow in popularity, a review of cultivars available through wholesale, retail and mail-order sources indicates that superior color selections and unusual flower types are still needed in several species and hybrids. In an effort to fill in a few of the gaps, the following cultivars are being propagated and will soon be available in the nursery trade. Some were selected for their value in breeding to further improve a particular trait and others for their bright colors or ability to undergo color changes.

Species Selections

'Cantrell's Double'* (temporary name) is a double red Rhododendron cumberlandense found in northern Georgia by Allen Cantrell of Chesnee, South Carolina. While there are several categories of double flowers, some of which can change from year to year, this selection has proven to be stable. The flowers have five wide petaloid stamens that lack pollen, but the pistils are fertile. Zone 5.

'Chocolate Drop'* is an unusual foliage selection of Rhododendron canescens found in a block of seedlings by Ernest Koone III, owner of Lazy K Nursery in Pine Mountain, Georgia. As learned the year after the slide of the foliage was taken, the plant has fragrant white flowers (bright pink flowers were expected). The chocolate-red foliage gradually turns dark green but secondary flushes of growth later in the season are also red, giving the plant the added attraction of having two colors of leaves simultaneously. Britt Smith and Frank Mossman found plants of R. occidentale in Oregon with similar red foliage but this may be a first for an East Coast species. Zone 6.

'Georgia Belle'* is a selection of a Rhododendron arborescens , a late-blooming variety of the sweet azalea. It was selected for its large, leathery, dark green leaves, late flowering and vigor. This variety differs from typical R. arborescens in several ways. It is usually found at less than 1,000 feet (300 m) above sea level in central and southern Alabama, Georgia and Mississippi, and it blooms in August and September. The fragrant white flowers have typical red pistils and filaments. Leaves are dark green above and light green below and are seldom, if ever, fragrant when crushed or have the glaucous blue green color common to upland or high-elevation R. arborescens . Also in bloom at this time and in the same general area is a population of R. viscosum formerly recognized as R. viscosum var. serrulatum . These two species are distinct, however, as the sweet azalea ( R. arborescens ) has smooth stems and the swamp azalea ( R. viscosum ) has smaller flowers and slender, hair stems. Zone 5.

'Nancy Callaway'* is a Lazy K introduction of Rhododendron alabamense . The Alabama azalea has a wide distribution range but it is not a common plant in the wild, having hybridized freely with R. canescens in many areas. It is highly variable and can be low and stoloniferous or tall and lanky. 'Nancy Callaway', named after a daughter-in-law of the founders of Callaway Gardens, was selected for its dense, spreading 5 feet x 5 feet (1.5 m x 1.5 m) growth habit and glossy foliage. The fragrant flowers are white with yellow blotches. Zone 6.

'Red Inferno'* is a Lazy K selection of Rhododendron flammeum that moves this heat-tolerant species several steps forward. It is noteworthy for its bright orange flowers that open with yellow blotches and later turn solid, bright red as well as for its vigorous growth habit and heavy wood. The thick, leathery leaves are dark green and longer than typical for the species. Zone 6.

'Terry Greer' is a foliage selection of Rhododendron alabamense that was found by Ms. Terry Greer in southern Georgia and later moved to her home near Travelers Rest in upstate South Carolina. The fragrant yellow-blotched white flowers are typical for the species. The plant is vigorous to 12 feet (3.6 m), and the widely elliptical dark green leaves have a ribbed appearance due to impressed veins. The undersides of the leaves are also covered with a white, glaucous powder when mature, and the leaves are fragrant when crushed, two traits shared with R. arborescens . The plant can also be found under the name "Frosty." Zone 6.

'Timberline' is a Rhododendron vaseyi that was selected for its slightly compact growth habit, bright pink flowers and red fall foliage. It was found at 5,000 feet (1,500 m) above sea level in the Shining Rock Wilderness in western North Carolina. Like other selections of this mountain species, the flowers may not be as pink at lower elevations as in the photograph. Zone 4.

'White Foam'* is a compact but vigorous Lazy K selection of Rhododendron viscosum . The numerous small, fragrant flowers are produced at an early age and are porcelain white. The petals have recurved tips, a trait fairly characteristic of this species. The growth habit is low and compact and the glaucous, blue-green leaves have a slight twist that makes identification easy when compared to other similar cultivars. Zone 5.

Hybrid Selections

'Chickasaw' is a natural hybrid of Rhododendron calendulaceum x R. periclymenoides found near Lake Keowee in upstate South Carolina. The large flowers, resembling those of the flame azalea, open light orange with a yellow blotch and quickly age to vivid salmon (orange-rose), a color that is very difficult to photograph. The flowers are covered with a network of darker rose veins, giving the flowers a distinct appearance. The light green leaves have impressed veins and are of good substance. The plant has a mature height of 8 feet (2.4 m) and is very floriferous. Zone 5.

'Doctor Helen'* is a Rhododendron calendulaceum x R. canescens hybrid found by physician Dr. Helen Sams, wife of physician and novelist Dr. Ferrol Sams of Fayetteville, Georgia. Helen spotted the plant along a roadside in northern Georgia, and they successfully removed layers to preserve the plant. This selection is distinct in several ways. The flowers open white and soon turn bright rose. The last few flowers on each truss open white after the first flowers have turned rose, giving trusses a two-toned effect. The plant is very floriferous and sets a large single floral bud on nearly every terminal. This forces lateral growth and produces a wide, spreading habit. Zone 5.

'Gamecock' is a strap-petal selection of a natural hybrid of Rhododendron calendulaceum x R. periclymenoides collected in upstate South Carolina. The flowers open pinkish orange with gold blotches and darken to orange-red. The petals are wide near their tips and have very narrow bases. Upper petals resemble miniature tennis racquets and the side petals resemble boat oars. The plant has a compact growth habit to 5 feet (1.5 m) and small micro-propagated liners have narrow leaves, a trait that becomes less obvious as the plants get larger. Zone 5.

'Goldbrick' is a natural hybrid of Rhododendron arborescens x R. cumberlandense found in the mountains of western North Carolina. It was selected for its bright yellow-gold flowers, red pistils and filaments, red petioles and hardiness. Growth habit is compact to 5 feet (1.5 m). Zone 5.

'Gold Lightning'* is an F ₂ seedling from a cross of ( Rhododendron arborescens x R. cumberlandense ) x ( R. arborescens x R. cumberlandense ), though it shows little R. cumberlandense influence. It was selected for its fragrance; gold-blotched light yellow flowers; red pistils, filaments, and petioles; and compact growth habit. Zone 5.

'Janet Jenkins'* is a natural hybrid of Rhododendron calendulaceum x R. canescens found in northeastern Georgia. The flowers open light pink and age to medium pink with small yellow blotches. The growth habit is low and compact, and the small leaves have felty upper surfaces similar to R. canescens . Zone 5.

'Keowee Sunset' is a natural hybrid of Rhododendron calendulaceum x R. periclymenoides found in upstate South Carolina. The large pink flowers have bright yellow upper petals and the tubes, pistils, and filaments are strawberry red. Leaves are long and wide with rounded tips, and the growth habit is upright and spreading with age. This color combination is common when an orange or red species crosses with a white or pink species, but this particular selection illustrates how efficiently both parental species can make their presence known in their offspring. Zone 5.

'Magic Pink' is a natural hybrid of Rhododendron calendulaceum x R. periclymenoides found along a logging road in western North Carolina. The slightly fragrant pink flowers, similar to typical R. periclymenoides in size and shape, age to bright pink with yellow blotches and finally solid red. The intensity of the color change is similar to that of 'Doctor Helen', with the final color being red instead of rose. The long leaves open light green and age to dark green. Zone 5.

'Mountain Creek White'* (see cover photo) is an F ₂ seedling of ( Rhododendron arborescens x R. prunifolium ) x R. viscosum . It was selected for its fragrance, slender-tubed flowers, wide flaring petals, red pistils and petioles, dark green foliage and overall vigor. Zone 5.

'Random Red' is a natural hybrid of Rhododendron calendulaceum x R. periclymenoides found in upstate South Carolina. Hybrids between these two species are usually easy to spot, but this one does a good job of hiding the R. periclymenoides side of its family tree. The flowers have orange throats and red petals with red-purple margins most years. The flowers are slightly smaller than those of R. calendulaceum and the small semi-glossy leaves and dense growth habit is more typical of R. periclymenoides . While it is not the reddest selection available, it is vigorous and easy to grow. Zone 5.

'Spring Pink'* is a natural hybrid of Rhododendron canescens x R. flammeum found near Pine Mountain Ridge in western Georgia. The fragrant flowers are vivid pink and the growth habit is upright to 8 feet (2.4 m). Zone 6.

'Spring Rainbow' is a natural hybrid of Rhododendron calendulaceum x R. periclymenoides found in upstate South Carolina. The flowers open light pink and age to strong purplish pink and finally to moderate purplish red. The yellow blotches age to orange and the tubes age from pink to strawberry red, with all colors showing simultaneously most years. The growth habit is typical of R. calendulaceum . Zone 5.

* Name is not registered.

Clarence Towe is a member of the Azalea Chapter. His recently published book American Azaleas is available from Timber Press.