JARS v37n3 - Dwarf Rhododendrons of the Caperci Nursery

Dwarf Rhododendrons of the Caperci Nursery
Lynn Watts, Bellevue, WA
Reprinted with permission from Arboretum Bulletin Summer 1982 Vol. 45 No. 2

The Nursery
For thousands of rhododendron collectors it was the end of an era. In October, 1980, the Rainier Mountain Alpine Gardens rhododendron nursery - owned and operated by Jim and Betty Caperci and internationally renowned as a source of outstanding species and hybrid rhododendrons as well as dwarf conifers - was sold.

Jim and Betty Caperci began their nursery in 1940 at a location approximately one mile north of the familiar South 126th Street location, in Seattle. They applied for their nursery license in 1946, and at that time named their enterprise Rainier Mountain Alpine Gardens. In 1952 they purchased 2½ acres from Elmer Fisher and moved the entire collection to the location that most of us came to know so well.

From 1940 until he retired in 1965, Jim Caperci worked as yard superintendent for Seattle Iron and Metals Corporation. During this time Betty tended the nursery during the day and Jim took over in the evening, often working in the greenhouse until 11 PM.

Contributors
In the beginning Jim and Betty grew only dwarf rhododendrons, but they soon became interested in the larger species. By the time they sold their nursery they could boast one of the largest collections of species rhododendrons in the United States. Over 500 separate species and several hundred choice hybrid varieties were included. Their plants were obtained from a wide variety of sources. Plants and seeds were sent to them by the American plant explorer, Dr. J. Rock. They also received many plants and seeds from Dr. John Creech, an explorer for the USDA and the collector of a number of plants from Japan, Taiwan and Korea. Included among these rhododendrons from Japan were the very beautiful dwarf Rhododendron kiusianum varieties and the forms of R. kiusianum which are, according to Dr. Creech, natural hybrids between R. kiusianum and R. kaempferi .

The plants in the Caperci collection from Dr. Creech include the dwarf forms of R. pseudochrysanthum and other rhododendrons collected in Taiwan and Korea. Others who contributed to the Caperci Nursery were Warren Berg, Frank Doleshy, the Ludlow and Sheriff expeditions, Dr. Rokujo, Hideo Suzuki, Koichiro Wada, Frank Kingdon-Ward, and the Rhododendron Venture expedition with Hsu and Patrick. The Capercis also raised a large number of plants from seed collected by the James Sturdevant expedition to the foothills of the Himalayas and Mt. Everest.

Plants grown from the seeds and cuttings sent to the Capercis by Hideo Suzukì include: Rhododendron kaempferi , various forms and varieties; R. mucronulatum , a dwarf form collected by Berg and Suzuki on Cheju Island; R. 'Nikkomontanum' ( nikomontanum ), a beautiful yellow dwarf, probably a hybrid of R. brachycarpum and R. aureum ; R. serpyllifolium and R. serpyllifolium var. albiflorum ; R. semibarbatum ; R. tsusiophyllum , now segregated as Tsusiophyllum tanakae ; R. kiusianum and varieties; R. macrosepalum , in various forms; and finally R. tosaense (komiyamae| .

Rhododendron Variations
Of particular interest to rhododendron growers and collectors are the variations in leaf shape and size, flower size and color, and plant habit, exhibited by individual rhododendrons that are closely related. These variations have been selected for the differing environments in which the plants grow in the wild. Moved into cultivation, the plants retain the varying characteristics. Several of the more interesting dwarf species grown by the Capercis are particularly intriguing because they exhibit these distinct differences.

Series Campylogynum
For example, Rhododendron campylogynum and its varieties are the sole members of the Campylogynum Series. This series includes R. campylogynum and varieties celsum , charopoeum , cremastum and myrtilloides and also the white form, leucanthum , possibly only a clone, but thought by many to be a true variety of R. campylogynum .

These are among the most attractive of the small-leaved dwarf rhododendrons. Especially desirable as rock garden plants in the more dwarf forms, they prefer to be grown in the sun and will flower more profusely than if grown in the shade. The plants in this series have dark shiny leaves which are ¼ to 1-inch long and variously shaped. Those of myrtilloides are sometimes attractively edged in yellow. The small, nodding, bell-shaped flowers, which appear in May, are borne on long slender peduncles and, depending upon the variety, range in color from white to pink, crimson, purple and deep plum-purple.

Rhododendron campylogynum itself is found in the wild in Yunnan, southeast Tibet, and west and northeastern Upper Burma at an elevation of 9,000 to 14,000 feet. The variety myrtilloides , the most dwarf of all the R. campylogynum varieties, bears dark crimson to plum-colored flowers. In the wild, variety myrtilloides is to be found at altitudes ranging from 8,000 to 15,000 feet.

Series Dauricum
The two members of the Dauricum Series are Rhododendron dauricum and R. mucronulatum . These two closely related species are important additions to our rhododendron collections particularly because of the early-flowering nature of both species. Frequently, R. dauricum will commence flowering in early December, particularly in milder winters, and will continue flowering well into April. Surprisingly, this precocious-flowering rhododendron does not seem to have a diminished floral display in March because of its December bloom. Generally, in our experience R. mucronulatum does not exhibit such an early flowering tendency, indeed it seldom blooms before January, although the exact date will depend upon the season. Both plants are hardy to -20° F.

In Rhododendron dauricum , the flower colors include a pale to deep, bright rosy purple, and a white form. Rhododendron mucronulatum's flower colors include a deep, rosy purple, orchid pink, rose pink, and white. The foliage of R. dauricum is semi-evergreen with a varying number of leaves being retained over winter. The leaves are elliptic and definitely rounded at both ends, dark, shiny, green, darkening during winter upon exposure to the sun. The leaves of R. mucronulatum are deciduous with a definite lanceolate shape, pointed on both ends. No leaves are retained during even our mildest Northwest winters. Evidently both R. dauricum and mucronulatum have been discovered several times in dwarf forms. We had been growing the dwarf form of R. dauricum for several years, when, in 1976, Berg and Suzuki collected seed of a dwarf form of R. mucronulatum from the summit of Mt. Halla San on Cheju Island, South Korea. (From seed of these plants Hideo Suzuki grew approximately 100,000 plants, of which only one had white flowers!) This particular dwarf form of R. mucronulatum , however, has rounded leaves with a slightly pointed tip. Also, the leaves are semi-persistent over winter. Thus, they are much more like leaves of R. dauricum in this respect. The flowers are of a rosy purple hue and the plants bloom at an early age from seed.

Series Triflorum
Rhododendron keiskei , the smallest member of the Triflorum Series, is a variable species ranging in size from a prostrate, ground-hugging dwarf to a tall open-growing leggy plant. Its flower color ranges from a pale yellow in the taller growing forms to a much more intense lemon yellow in the dwarf form, a clone of which is 'Yaku Fairy'. The leaf of R. keiskei is quite variable in size and shape, but it is always recognizable because of its slightly asymmetrical shape. Even in first generation hybrids this leaf characteristic provides a ready clue to keiskei , parentage. It should be noted that all of the forms of R. keiskei develop a bronze-red winter coloration of the foliage if grown in the sun. In Japan, R. keiskei is found only at elevations of 2,000 to 6,000 feet.

With the introduction of 'Yaku Fairy' we have three forms of R. keiskei in cultivation. Rhododendron keiskei var. cordifolium 'Yaku Fairy' was originally found growing on the summit of Mt. Kuromi, a 6,500-foot-high peak on the island of Yakushima in the Japanese Archipelago. This geographical range is restricted to a small area on the very top of that mountain, and although collecting this rhododendron has been prohibited by Japanese law for many years, it continually remains in danger of extinction in the wild. In our nursery we have a group of approximately 30 first-generation seedlings of 'Yaku Fairy'. These plants are now seven years old and exhibit that range of variability to be expected from hand-pollinated seedlings of any species. The smallest plant in this group is now ¾ inch high and 2½ inches in diameter with leaves less than ½ inch in length and barely ¼ inch across.

Series Barbatum
Found in the wild only on Taiwan at 6,000 to 13,000 feet and only recently introduced into the United States, R. pseudochrysanthum presents us with another dwarf rhododendron which is quite variable in stature and in leaf size. Rhododendron pseudochrysanthum , a member of Series Barbatum, ranges in height from the very recently introduced dwarf alpine forms which are now, at the age of six years, only 1½ to 2 inches high, with a diameter of 4 to 6 inches, to the taller growing forms which may attain a height of 9 feet. An intermediate form in our nursery is now 8 inches tall and 20 inches in diameter at 20 years of age. As might be expected the leaves vary in size in direct proportion to plant size. Leaves up to 4 inches long and 1¾ inches wide are found on the tall-growing forms, while the leaves on the dwarf alpine form are barely 1¼ inches long and ¾ inch wide, Most forms have a definite pubescence on the mid-rib of the under leaf. However, the dwarf alpine forms collected by Creech and Suzuki quite often are colored a shiny, deep maroon-red on the underside of the leaves. This color is usually the precursor of indumentum. Flowers first appear dark pink in the bud, but become pale pink or white when they open. Rhododendron pseudochrysanthum is somewhat slow to flower, but once it attains flowering size it presents a magnificent display. This species prefers exposure to full sun to maintain its dwarf and compact habit and to bloom most profusely.

Undoubtedly many undiscovered species and varieties of rhododendrons still exist in the vast, relatively unexplored regions of China and Russia. What an exciting experience it would be to discover a previously unknown rhododendron and to be the one to introduce this new species to the public!

Hybrids
In addition to the fine selection of species rhododendrons which were offered to the public by the Capercis, rhododendron hybrids were also available. Most of the hybrids were very choice, hard-to-find dwarfs, Included in this selection were some of Warren Berg's hybrids which were made available to the public through the propagating efforts of the Capercis.

Jim and Betty had met Warren Berg as the result of their mutual interest in rhododendrons. Warren was a careful and selective hybridizer who used R. yakushimanum extensively. He also used 'Yaku Fairy', the rare, choice and extremely dwarf form of R. keiskei as one parent in a series of crosses, many of which produced charming dwarf hybrids.

Betty and Jim Caperci enjoyed naming their own hybrid dwarf rhododendrons after their offspring. Three of their hybrids were named after their daughters:

'Bobbet' ( R. campylogynum x R. campylogynum var. cremastum ). This delightful small-leaved dwarf rhododendron bears yellow-pink bells in May and June.

'Maricee', AE ¹ (selected R. sargentianum seedling). The delicate creamy-white flowers which appear in early May form a tight, miniature truss on this dwarf-growing, small-leaved rhododendron. The peeling white bark provides an interesting highlight. Grown in full sun, this plant will be eight to ten inches tall in ten years.

'Patricia' AE (selected seedling of R. campylogynum var. charopoeum ). This more robust R. campylogynum with magenta-purple flowers which appear in May, tends to be upright and quite open-growing in the shade but will fill in and be quite dense and more compact if grown in the full sun. It will be 12 to 16 inches in height in ten years.

Six of the dwarf hybrids developed by Jim and Betty were named after granddaughters:
'Candi' ( R. campylogynum var. cremastum x R. racemosum ). Bright rose flowers are carried in axillary trusses on this low-growing dwarf which blooms in late April. The R. racemosum influence is quite apparent in this hybrid, which appreciates exposure to full sun.

'Debijo' ( R. carolinianum x R. saluenense ). Pink flowers adorn this plant which is intermediate in size between the parents. It blooms in early May.

'Kim', AE ( R. campylogynum x R. campylogynum var. cremastum ). This tight-growing, award-winning dwarf rhododendron has pink buds that develop into little bell-shaped yellow lanterns. It blooms in May.

'Liz Ann' (selected R. sargentianum seedling, not registered). For many years this plant was referred to as Pink Maricee. The flowers are similar to those of 'Maricee' but pink in color. It blooms in May.

'Meliz' ( R. kotschyi hybrid). The small pink flowers appearing in May are spotted with darker pink. The leaves are smaller than the typical R. kotschyi , now renamed R. myrtifolium .

'Sheila Ann' (parentage unknown, probably a hybrid of R. sanguineum ). The flowers are deep blackish red, and the leaves are of the larger R. didymum style. Flowering is in late May to June.

Two other dwarf rhododendrons were hybridized and named by the Capercis:
'Carousel' ( R. carolinianum x R. saluenense ). This hybrid has lavender-pink flowers and a plant size similar to 'Debijo'. It blooms in late April.

'Patches' ('Chichibu' seedling). This prostrate azalea blooms with orange and white flowers in May or June.

Additional plants registered by the Capercis but not necessarily hybridized by them include:
'Caperci Special' (parentage unknown, probably a hybrid of R. triflorum ). This plant was propagated for several years by the Capercis but not named. Then it was entered in a local Northwest show by an exhibitor who gave it the name under which it is now registered. Pink flowers appear in April on a plant which will be no taller than 12 inches in 20years.

'Ernie Dee' ( R. dauricum x R. racemosum ). Mr. Ernie Dzurick made this cross and gave the plant to the Capercis who named and propagated it. The flowers appear in April and are lavender spotted with red.

'Golfer' ( R. yakushimanum x R. racemosum ). Hybridized by Warren Berg and given to the Capercis, 'Golfer' was registered under that name in recognition of Mrs. Berg's love of golf. The flowers are white with a pink flush. Bloom is in May. The leaves are heavily tomentose below and above, and maintain indumentum on their upper surface for most of the year.

'Rudolph's Orange' ('Fabia' x 'Temple Belle'). Hybridized by the late Rudolph Henny and given to the Capercis for propagation, this was named and registered by the Capercis after Mr Henny's death. The flowers are orange with a pink flush and the plant blooms in May.

In recognition of his many and varied contributions in the field of rhododendron hybridization, propagation and distribution, Jim Caperci was awarded the Gold Medal by the American Rhododendron Society in 1974. He also received the Bronze Medal from the Seattle Chapter of the American Rhododendron Society in 1976. In addition to these two major awards, Jim Caperci was honored by the Rhododendron Species Foundation with the first Citation granted by that organization. No rhododendron enthusiast who ever visited the Rainier Mountain Alpine Gardens will forget the warm enthusiastic hospitality of Jim and Betty Caperci. The coffee pot was always on and they were never too busy to take the time to make everyone welcome. They will be remembered also for their outstanding collection of species rhododendrons and the spectacular display of these plants in full bloom. Thanks Jim and Betty Caperci. Your plants will be an everlasting tribute to your work.

¹ AE. Award of Excellence by the American Rhododendron Society.