Hybridizing at Rhody Run, West Virginia
Chipps, Tipps, Tripps and Slipps
W. L. Tolstead
Elkins, West Virginia
My first encounter with rhododendrons was in Red Wing, Minn., at the Buckholtz Greenhouse in 1924-28. I specifically remember 'Madame Pericat'. It was not, however, until the early spring of 1942 that I found my first wild azalea, located in a wet, sub-irrigated meadow 50 miles west of Lincoln, Neb., in Saline County in the Saline River Valley. It grew on the south side of the west-east road on the edge of a tall-grass prairie, on the north side of the valley.
I was led to this find by a note on the bottom of the page of a publication "Ericaceae section of the Flora" presented by the Botany Seminar at the University of Nebraska in the early part of this century. This seminar planned to describe the flora of Nebraska. Although only one small part of this paper was printed, it was never distributed. It was found in the storeroom in the Botany Department by graduate students in 1942. The university library does not have a copy, but one may be found in the T.J. Fitzpatric Library at the University of Kansas. At this early time I did not collect specimens, hoping to return in mid-May. This, however, was not to materialize because I was drafted into the army. I was never able to return to this spot, and there is not an herbarium record. This must be regarded as a casualty of war. Does anyone want to take a shot at this azalea after 50 years? I believe this species was Rhododendron nudiflorum.*
In the war period until 1957, I saw rhododendrons in Kew and Lansdown Estate in England and in the Willamette Valley in Oregon. It was not until 1958 that I was finally able to grow rhododendrons, when I bought an old farm near Elkins, W. Va., and named it Rhody Run. Here I have lived for 31 years, growing 1,499 seed collections from which I have grown thousands of plants with varying degrees of success and failure. These Dexter hybrids were originally obtained from F. W. Shoemaker.
Rhody Run is a hilly spot of 50 acres covered mostly with oak, with about 30 acres of rhododendron plantings. The soil is Devonian clay with a pH of about 5.5. Average rainfall is 42 inches and summers are mild, with temperatures seldom reaching in the 90s. Some years experience periods of drought. Winters alternate between warm and cold spells with late spring frosts into mid-May. In 1985 and 1986, temperatures fell to -26° and -28°F. Late flowering rhododendrons are best; even early flowering daffodils have a hard time.
It is desirable to carry on planting breeding programs in severe and erratic climates so that selections can be tested for hardiness and vigor, and also for lateness of flowering in late May, and early June. This does not indicate, however, that this is an ideal area for commercial purposes. The growing season is short, and length of time required to produce marketable cuttings runs from four to six years. Usually only one flush of stems is produced each year. The isolation of the area, and the non-interest of the local public both contribute to low marketability in face of high production costs.
Three species of native azaleas grow naturally at Rhody Run, R. nudiflorum, R. calendulaceum, and R. arborescens, which grows only along stream banks, and blooms in mid-June. The most northerly record for R. catawbiense is on Lookout Mountain about 75 miles southwest of Elkins. R. roseum** grows on top of windswept mountains at 3,000-4,000 feet, where tree growth is sparse and it flowers in early June. When transplanted to my place at 2,000 feet, it flowers four weeks earlier. All of the rhododendrons flower after May 15th. This is probably an adjustment to characteristically late frosts. R. nudiflorum is characteristically earlier than R. calendulaceum and becomes stoloniferous in very shady, rich soil. Both species seem to thrive on soils derived from shales that are droughty and where overgrowth of oaks is open and widely spaced. R. calendulaceum with near white to red flowers is not stoloniferous and is a tetraploid. R. nudiflorum is diploid with white to light pink or lavender flowers. All these species are isolated genetically by environmental factors and have innate flowering traits, and hybrids do not usually occur. R. calendulaceum is genetically more variable and has wider environmental adaptation than the other two species which seem quite uniform.
The native azaleas still are open to the plant breeder; R. calendulaceum is especially good because of its great variability. I should have worked with these instead of putting so much energy into the somewhat marginal obtusums; after all, they are a warm, largely temperate group of plants from rainy, warm Japan, and in my location the majority of these species have difficulty surviving. I have a few F1 segregants that survived the extremes of temperatures in 1985-86. Some flowered and produced much seed from which I have a number of plants.
Two dwarfs, R. kiusianum from 6,000 feet in Kiusiu, and R. nakaharai from Mt. Morrison in Taiwan produced a good, hardy, dwarfish pink hybrid. The Korean obtusum flowers much too early to make a show here. These two southern species probably suffer cold spells coming out of the Asian continent at alternate periods during late winter and early spring. This meets one of the requirements for survival in the eastern U.S.
'Delaware Valley White' comes close to being the hardiest obtusum azalea in our area. It appears to belong to R. ripense that is native along the rivers in southwest Japan. This block of Japan is a product of continental drift, which in this case originated on the Asiatic shore of the China Sea, and drifted east across it until it hit the landmass of ancient Japan - carrying with it the cold-resistant ancestor of modern R. ripense. R. ripense maintained its hardiness acquired on the Asiatic mainland over periods of thousands of years and still maintains its hardiness in its new home on the American continent.
The east American native elepidote R. maximum grows abundantly on hilltops, beneath deciduous trees, on cliffs, and in swamps. Few rhododendrons are more resistant to cold. This species flowers late, July through August, and has very sticky flowers that last only a few days. It may grow to 20 feet. Some plants may be very old, having regenerated from fallen stems with roots surviving after the tops are destroyed by fire or other disaster. In spite of these characteristics, and because of them, this species is difficult for the domestic plant breeder and has been used very little by breeders. Genetically it carries a large quantity of dominant genes.
By contrast, the elepidote R. catawbiense is just as hardy, flowers earlier and longer, with flowers in a variety of colors, is more bushy, and is not as dominant genetically. Most of my elepidotes have at least some hardy catawbiense genes though sometimes it is not very obvious. I have used this species extensively to cross with R. fortunei. These crosses gave mostly plants with white, pink, and lavender flowers. Especially in recent years I have also made crosses with R. haematodes hybrids that are very beautiful dark reds and very dark purples that are hardy in this area. These hybrids are quite variable; some are very much like R. catawbiense and others are R. fortunei-like types that would confound the taxonomist. Crosses between R. yakushimanum and these hybrids have made a tri-specific that is large, white-flowered, thick-leaved, and dwarfish. A number of crosses with R. catawbiense have yielded a number of small, dwarfish plants.
When I first started my crosses there were only a few carolinianums that were hardy here. I now have very hardy types that flower from early to late and grow from dwarf to tall. I have developed a strain of tetraploid R. carolinianum by selecting large seedlings in the cotyledonal stage. Using the third generation, I have made crosses with R. racemosum which was also tetraploid, and which I induced by colchicine. These are very hardy, dwarfish plants which have good possibilities for future use. I have one strain of PJM-like hybrids that always flower too early to be of much value here. I have also worked with Lapponicum species, with no promising results.
Janiki Amnal lists chromosome numbers of over 350 species. Since she did not publish her methods, they are subject to debate and speculation. After considering several possibilities, Dr. Joe Glencoe and I concluded that Amnal used freshly germinating seeds, one to two weeks old, at which time the first flush of mitosis may occur. Unfortunately, the untimely death of Dr. Glencoe made the continuance of our work impossible, and I do not see well enough to continue. Seed can be readily collected and transported over long distances with a minimum of expense, and the necessary materials can be readily obtained.
Because of our extreme climatic conditions, we are relatively free of insect pests and fungi, but in the recent four to five years, grazing deer have become a problem because of excessive governmental protection. These voracious animals not only destroy our rhodies, but also are eliminating from our flora a number of wild species. When I first came to this area, there were very few deer, seen only occasionally in the winter, but now they come to stay all year along. The only good deer is a dead deer.
Economically, it would have been well if I could have had a grandfather who would have left me several plants to start out from, but I was already 41 years old when I started breeding plants and had accumulated enough capital to carry on this rather expensive hobby. Financially, I didn't do this on my professor's salary; but with the help of good and dependable friends, I was able to grow West Virginia rhododendrons with money from Iowa corn and beans. Specifically involved were Gene Verheul and Paul Terlieuw. I am also thankful for the physical labor of good-natured neighbor boys with a sense of humor. In later years, David Travers and John Roberts, Willie Newhouse and Dr. Joe Glencoe, were my special helpers. My rhododendron patch was an extended classroom for my biology students, and I also met many friends in distant places. All this established another dimension in my work in life. In the words of John Keats, "A thing of beauty is a joy forever: Its loveliness increases; it will never Pass into nothingness; but still will keep. A bower quiet for us, and a sleep Full of sweet dreams, and health, and quiet breathing.
Dr. W. L. Jolstead is a professor of Biology at Davis & Elkins College, Elkins, W. Va. Dr. Tolstead co-authored an article in the spring 1991 issue of the Journal, 'Winter Hardy Tetraploids of Rhododendron carolinianum and Rhododendron racemosum, and their tetraploid hybrids.
* R. periclymenoides (syn. nudiflorum)
** R. prinophyllum (syn. roseum)