R. nakaharai And Some North Tisbury Hybrids
Mrs. Julian W. Hill, Wilmington, Delaware
A reprint from "American Horticulturist," Spring, 1973, Vol. 5, No. l
R. nakaharai from Mt. Seven Star
Photo by Julian W. Hill
The village of North Tisbury lies two to four miles between the north and south coast lines of the island of Martha's Vineyard, Massachusetts. There, at Barnard's Inn Farm, since 1957, I have been growing a number of Japanese azaleas. The seed to produce my plants was imported through the kindness of Dr. Tsrmeshige Rokujo of Tokyo, who hybridized and collected for me. He made the appropriate crosses to meet my objectives, namely to produce prostrate, hardy, evergreen forms to be used as ground covers. In addition to the tailor-made seeds he sent me a few choice species and hybrids as rooted cuttings, both named and unnamed, through the usual import channels sanctioned by the U. S. D. A. Only those hybrids raised by me from seed at Barnard's Inn Farm are given the covering name of North Tisbury hybrids.
To achieve the prostrate and evergreen character the species R. nakaharai was largely used. To achieve a variety of flower forms and colors other garden azaleas were used in the crosses. Fifteen years of attrition of the tender, weak, and otherwise undesirable have left me with a number of plants, well suited to this area and to the designated objectives. Further testing in other areas is in progress.
R. nakaharai, native to Taiwan and long grown in Japanese gardens, is an evergreen species too little known in this country. It is so flat on the ground that two to five inches covers its height after ten years. The twiggy mat with small, dark green, hairy, pointed leaves and brick red twin flowers make it a little gem for rockeries or intimate borders. The hybrids of R. nakaharai have an even greater hardiness than the species. The many branches spread vigorously in a horizontal manner and the gradually mound to ten to fifteen inches with a spread of thirty to forty inches in ten years. They make a serviceable, fine textured. and distinguished ground cover, flowering late in the season, in time and July, depending on the climate. In my experience, open pollinated progeny of R. nakaharai give evidence of ready promiscuity, for only one out of fifteen plants exhibit all the characteristics of the true species. The others have nodal extension, cold hardiness, extra flower size, and color variations from light pure red to deep orange red. I have yet to see any purple or crimson toning in a R. nakaharai species or hybrid. Most of them are in the 513 sheet of the Munsell color fan. All the colors are bright and carry well at a distance.
A very special plant of R. nakaharai has come to me through a rather romantic story, Mrs. Ann Fielder, whose husband was in the service in Vietnam, decided to take her five children to Taiwan for a few years to be near him. I asked her if she would like a project. (As though five children were not enough.) So I gave her a few branches of my open pollinated plant as a sample and suggested she find the real thing in the wild, possibly on Mt. Morrison. Later I suggested she contact the Botany Dept. of the Tai Da University in Taipei for specifics.
Many searching expeditions and many months later her teen-aged son, somersaulting down Mt. Seven Star on a picnic, landed in a bush and said. "I have found it". Indeed he had. Not too long after I received a small envelope from Prof. C. S. Kuo of Tai Da University containing a pinch of dust. Under the microscope I estimated there were about forty seeds in all. They were gathered at 800 meters on Mt. Seven Star on November 16, 1969. I planted them on the 10th of December. On January 10, 1970, two seeds germinated and ultimately one lived. That one plant wintered under lath in my nursery at North Tisbury in 1972 and grew and blossomed last summer (1972) at a time when all the Fielders, united in the U.S.A. were again on Martha's Vineyard and could see it.
The little R. nakaharai from Mt. Seven Star has the finest form of any R. nakaharai I have yet seen. It is low and dense in growth, its leaves are furrier with longer red hairs, it flowers are larger than others of the species and of a most deeply saturated red, (5R5/13 vivid red), it will be carefully observed in the years to come.
North Tisbury hybrids include a variety of crosses. My R. nakaharai open pollinated seedling #1 is named R. 'Marilee', and my #2 is named R. 'Wintergreen'. These are both low dense plants of vigor and class. The flower color of R. 'Marilee' (2.5 R 7/8 to 6/11 blotched on three lobes 4/10) has excellent carrying power and blooms later than any of its siblings into the first half of July. The winter leaf color is smoky purplish where exposed to direct sun. R. 'Wintergreen' makes a perfectly circular mound with a specially fresh green color all winter. The five-lobed blossoms of R. 'Wintergreen' are 6½ cm. wide and 5 cm. long (2.5117/8 to 6/11 blotched 5/12) a light red or deep pink. Once established they do not seem to mind temperatures down to minus 4°F.
The Satsuki azalea R. 'Chinyeyi', which is white, crossed with pollen from R. nakaharai, has yielded some sparkling light pinks with open frilly flowers. This sturdy and twiggy plant is also low and mounded in habit. R. 'Michael' is the #1 of this cross. The flowers are 6-1/2 cm. wide and 5 cm. long, the color is a bright pink (10 RP 7/8 to 6/12 blotched 4/12).
R. nakaharai crossed with R. kaempferi yields a compact but upright plant of dependable hardiness, full evergreen habit and a gaudy solid red color display, in late May and early June. The two parents are about equally evident in the progeny. The open up-reaching habit of R. kaempferi is dwarfed by the cross making a compactly branched but vertical plant, about one meter high by one meter wide in ten years. It blooms at the same time as Gable's R. kaempferi hybrids but holds green leaves all winter. The flowers are massed in shades of 5 R.
Dr. Rokujo admires an English azalea named R. 'W. Leith' for its red flowers and fine habit and has made reciprocal crosses with R. nakaharai. The plants I raised from these seeds have produced a very hardy and handsome group of azaleas. R. 'W. Leith' x R. nakaharai #1 has a dark green leaf, very low wide spreading habit and brilliant red flowers which occasionally produce petaloids. This gives the effect of bright red roses standing out among the green foliage. These flower buds are not always as winter hardy as some other selections. One sibling of this cross is taller, to forty-two centimeters and ninety centimeters wide, but with a tight billowy habit that is particularly handsome. The reciprocal cross has produced much the same variation in habit. It is possible to single out one or two outstanding individuals. The brilliant flowers are 5 R 6/11 to 5/13.
R. nakaharai x R. 'kin-no-sai' #1 is the hardiest plant of all the North Tisbury hybrids. Bright red flowers come through the toughest situations of sun, wind and drought on prostrate, lightly billowed plants, fine textured in leaf, dark green in summer, and purple grey green to bronze in winter. I have named this one R. 'Alexander'. This plant would curve down over a bank or wall as well as hug the ground.
A North Tisbury hybrid not involving the species R. nakaharai is R. 'Chinyeyi' x R. 'W. Leith'. The #5 is a lovely fresh pale pink I have named R. 'Louisa'. It takes several years in my climate to become established and flower, as it is not so hardy in small sizes as the R, nakaharai hybrids. The flower color is 10 RP 6/12 to 7/8, 5 cm. broad x 5 cm. long, the leaf is very narrow, the plant habit low and suitable for ground cover.
There are three North Tisbury hybrid selections that do not appear to include the species R. nakaharai in their immediate parentage. These three I call the Music Street Trio, named for the principal residential street of West Tisbury. They are R. 'Andante' pink, R. 'Trill' red, and R. 'Hot Line' crimson. Dr. Rokujo wrote on the seed envelope, "selections from dwarf new Gumpos". The seeds were gathered in 1962 from one of the finest collections of these Gumpos, or Satsukis, in Tokyo. My plants are compact but not prostrate, the flowers are large and ruffled. The hardiest is R. 'Hot Line', but all three are less hardy than the R. nakaharai hybrid selections. In fact, they compare with the average Satsuki azalea in general adaptability and would grow better in the Washington, D.C. area further south. R. 'Hot Line' is purple red, not unlike R. 'Glamour' in color, of good compact, but not prostrate, habit. R. 'Trill' is a medium red and ruffled, also compact. R. 'Andante' is a large flowered pink and ruffled, but with a definitely upright habit. R. 'Andante' and R. 'Louisa' would be two good pinks to grow together, with R. 'Andante' planted to the rear.
The North Tisbury hybrids that have been propagated from summer cuttings all seem to root easily, and, of course, their habit of lying low on the ground makes layering appropriate and successful. Like most of the Japanese azaleas these plants need plenty of light to bloom well. They tolerate sun better than they do wind. Perfect drainage and a good mulch are essential. If rabbits are a local pest the plants will need protection from September until June.
It is regrettable, that even in our northern latitude, the wet spring of 1972 encouraged petal blight on a wide range of species and hybrids, including the North Tisbury hybrids.