JARS v52n4 - Selections from the Polly Hill Arboretum

Selections from the Polly Hill Arboretum
Polly Hill
Hockessin, Delaware

Having reached the stage of rhodoholism where my preference is for species over hybrids, I am selecting the following fifteen of my species rhododendron introductions to present in detail. Three American natives came from the Cumberland mountains, the seed kindly shared with me by Mr. Olin Holsombach of Georgia, who hiked the 10 miles up the mountain to Gregory Bald to collect them. Their names are 'Chalif, 'Sizzler', and 'Sunlight'. All are tall, deciduous, June-July blooming plants.

'Chalif': 'Chalif' is the first to bloom, overlapping the bloom time of the species Rhododendron calendulaceum . Its color is a blend of yellowish pink, reddish orange, and orange, 8 to 10 feet (2.4-3 m) of riotous color, and best seen among a planting of greens.

'Sizzler': Next to bloom is 'Sizzler', a little less tall, with flowers colored a hot red-orange with bullate dark bluish foliage.

'Sunlight': The third, my favorite, is 'Sunlight', a 4th of July celebration in itself. 'Sunlight' is worthy of the name. The color is an exhilarating mixture of orange, rose, and old gold. It is also a tall plant of 8 to 10 feet (2.5-3 m). To me 'Sunlight' is quite simply gorgeous. All three R. cumberlandense selections appreciate a little shade.

'Marydel': 'Marydel' was selected in the wild from a stand of native azaleas in central Delaware near the Maryland border. (Henry Skinner says this stand is a wild hybrid of R. atlanticum and R. periclymenoides .) Stoloniferous, it spreads rapidly, easily making a solid hedge from a few plants. Intensely fragrant, the flowers are white tinged with pink. The Choptank River at its headwaters has given its name to the seedlings of this cross. Deer, rabbits, and other pests do not bother it. The height of the plant seems to vary with the amount of moisture it receives. In dry sunny meadows the plants stay down to 2 or 3 feet (0.6-0.9 m). In shade they can grow to 8 feet (2.5 m). The color and scent are delightful.

'Delaware Blue': The name honors the Delaware regiment known in the Revolutionary War as Blue Hen's Chickens. Rhododendron viscosum grows wild over much of the East, from Maine to Louisiana. My selection I have named for its bluish green foliage, which is especially noticeable late in the season. I collected the plant in the wild in Delaware near the Choptank River. Given moist soil and sun the tall plant bears an abundance of fragrant flowers, somewhat sticky to touch.

'Lady Locks': Seed of 'Wakasagi', open pollinated, provided the selection 'Lady Locks'. A frothy profusion of light purple color and rich fragrance are two of its outstanding qualities. The plant is upright to 6 feet (2 m)with spreading branches like a table top and blooms along with purple iris in early June.

'Zeke': Another Japanese species, R. sanctum , preserved in the Ise Shrine, is very rare now in the wild. It grows to 15 feet (4.5 m) and bears richly crimson flowers reminiscent in form of the American species R. vaseyi . The lustrous rhombic leaves give the plant elegance at all seasons. It is possible that USDA Zone 7 is safer for its survival than Zone 6 where I am growing it.

'Wild Wealth': The species R. yakushimanum grows high in the mountain top of the Yaku Island, southern Japan. My plant 'Wild Wealth' was grown from seed from that mountain. The name honors Marian Becker, author of a book by that name, and refers to the treasure found in the species itself. My 'Wild Wealth' is now 7 feet tall (2 m) and 10 feet (3 m) wide, flowering from deep pink to white, and with short glossy recurved leaves, bearing thick white to tan indumentum. It catches the light and one's attention wherever it grows. Given its provenance one can safely say, "This is a real Yak."

'Mount Seven Star': The species R. nakaharae is endemic to Taiwan. 'Mount Seven Star' is the English name for the mountain where my seed was collected. The plant blooms late in June, is low growing and tightly twiggy, with dark, round leaves. The flowers are pure cadmium red, a splendid sight in bloom. Once established it becomes a memorable feature in the garden - a ground cover azalea.

'Nakami': In Japanese the name means "beautiful nakaharae." The parentage is nakaharae , open pollinated. The plant is a true miniature, 20 inches (50 cm) across in 25 years from seed, a natural for the rock garden. The flowers are red, the foliage round. It is not many inches tall.

'Fuzzy': A wild seedling of R. nakaharae possibly crossed with the species R. oldhamii was introduced by John Creech for the USDA in 1971. 'Fuzzy' is appealingly furry, inviting touching its soft hairy leaves and twigs. The flowers are red. The plant is 2 feet (0.5 m) tall and 4 feet (1 m) wide in 30 years. For hardiness 'Fuzzy' is better sited in Zone 7 than Zone 6.

'Libby': Dr. Rokujo of Tokyo sent me seeds of open pollinated R. kaempferi . I have named two selections from that seed. 'Libby' is pink tinged with lavender. It is the kind of pink one can plant in quantity and find satisfying. 'Libby' is an abundant bloomer of compact stature, not stoloniferous, enjoying rich, moist soils.

'Corinna Borden': The other selection of the open pollinated white form of R. kaempferi , 'Corinna Borden', is compact and twiggy, but abundantly smothered in the palest of light purple flowers. This pale shade makes it even more useful than white as a blender of strong colors in the border.

'Lydia Richards': The species R. makinoi is closely related to R. yakushimanum . This cultivar from Japanese seed has long slender leaves, 7 inches by 1 inch (17.5 x 2.5 cm), and thickly indumented with white to tan felting. The large trusses of flowers bloom in late May a deep rose, fading to pink. The new leaves stand tall in July and August, their white indumentum catching the light. This compact plant is a massive rhododendron 7 feet (2 m) tall and 10 feet (3 m) wide.

'Temple Flutes'*: Of the three, 'Wild Wealth', 'Mount Seven Star', and 'Temple Flutes', the latter stands out as one of the three most important introductions I have made. What does one look for in a rhododendron? Compact growth, abundant branching, great colorful trusses on every branch, foliage a deep green and glossy, and well shaped with heavy indumentum. This plant has it all. It is 6 to 8 feet (2-2.5 m) high and 10 feet (3 m) wide. The furry upright leaves, 7 inches (17.5 cm) long and ⅞ inch (2.5 cm) wide, glint gold all summer in upright position before spreading out in repose. Rhododendron makinoi , the species, is endangered in the wild but these seeds came from Japan, where it grows near the Ise Shrine. The ARS Seed Exchange in 1967, #182, from Takeuchi and Wada, was my source.

Only time will tell which ones of these 15 will still be gracing our gardens in the next 50 years.

* Name is unregistered.

Polly Hill authored the article "Salt Blackened Shingles and Old Granite: Barnard's Inn Farm" (Winter 1994 issue) which includes a comprehensive list of her introductions.