JARS v44n2 - Rhododendrons at Arnold Arboretum

Rhododendrons at Arnold Arboretum
C. J. Patterson
Norwell, Massachusetts

"Indeed, a park and an arboretum seem to be so far unlike in purpose that I do not feel sure that I could combine them satisfactorily." So wrote Frederick Law Olmsted to Charles Sprague Sargent in a letter in 1874. Considered the most talented and innovative park designer of his day, Olmsted had been brought to Boston during the planning phase of the Arnold Arboretum to design the layout of the park. There he met Sargent, the first director of the Arnold Arboretum and an equally dedicated and talented man; together they worked to accomplish the unlikely. The success of that collaboration can now be enjoyed by every casual jogger and serious botany student that strolls its trails or labors in its laboratories.
The Arnold Arboretum, the oldest in the U.S., was founded in 1872, but the foresight of the design makes it seem very modern today. " ... it was necessary to devise a system of roads and walks which should make easily accessible to a large number of visitors every plant in the collection, and which, without interfering with the scientific necessities of arrangement, should open up and develop, as far as possible, the remarkable natural beauties of the grounds."- The design almost literally has something for everyone. Broad vistas of well-planted valleys and meadows give the visitor a park-like view, with room to roam and relax, while wide wooded trails can give the stroller a feeling of being many miles from the heart of a major city. More intensively planted areas like Bussey Hill give a more intimate feel, a garden within a park, that invite the visitor to explore and examine the plantings more closely.

And then there are rhododendrons. Lots of rhododendrons. At last count there were 371 species, varieties and cultivars in the collection, and over 1,500 individual plants. They were one of Sargent's favorite plants and Olmsted used them lavishly to soften the taxonomic arrangement of trees in the arboretum. Here, too, the effect they give is varied. Along Azalea Path on Bussey Hill, for instance, azaleas line intimate walkways where they can be touched and smelled and appreciated close-up as individuals. In contrast, whole hillsides below Oak Path blaze during late May and June with broad plantings of native American azaleas, literally acres of azaleas. It is one of the most spectacular sights in the arboretum.

Although a casual visitor may appreciate the timelessness of the landscape, for the rhododendron enthusiast it has a special meaning. Except for the sequential planting of azaleas along lower Meadow Road, all of the major plantings of rhododendrons are unchanged from the original plantings. Individual plants may be added or subtracted, but visually they remain very much the same as in Sargent's time. A visitor looking at photographs of Bussey Hill taken in the 1920's would have no trouble recognizing Azalea Walk and the plantings there. One could stroll along dense trails, in the very footsteps of Sargent, imagining the swish of starched skirts and the rattle of carriages from the roadways. In the large planting of broad leaved rhododendrons at the foot of Hemlock Hill, the feeling of deja vu is the same; the pictures show a neat grassy path between banks of rhododendrons, with hemlock trees behind. The path is still there, though no longer grassy, the rhododendrons are larger, the hemlocks more prominent, and one can still take a flowery walk in early June pausing, perhaps, to examine a truss more carefully or to listen to the murmur of Bussey Brook at the foot of the hill.
Rhododendron history is present at the arboretum not only in its vistas and walks, but in individual plants as well. The first rhododendron accession recorded here, R. calendulaceum , was grown from seed sent from a botanical garden in Paris in 1876. It is still in the collection, along Meadow Road, one of the first plants to be planted in the arboretum. At the beginning of Wilson's Walk on Bussey Hill is the first group of R. schlippenbachii introduced into the U.S., raised from seed collected in Korea in 1905 by J. Jack, the arboretum's propagator. People are represented in the collections, too. When Joseph Gable became interested in rhododendrons, one of his first contacts was the Arnold Arboretum. Sargent wrote back personally, and encouraged the young nurseryman with pamphlets, books, letters and more importantly, seeds and plants. Gable remained a friend of the arboretum all his life, and in later years sent samples of his work, which were eventually planted out along Bussey Brook. Today you can see such Gable hybrids as 'Caroline' and 'Cadis' thrive, as well as unregistered hybrids like 'Maxhaem Salmon' and 'Maxhaem Yellow' and R. maximum x R. discolor .

Charles O. Dexter was befriended by the arboretum also. E.H. "Chinese" Wilson, who managed the collection after Sargent's death, was much impressed with Dexter's work, and sent him seeds, pollen, and plants. Dexter responded by sending two carloads of his seedlings to the arboretum, as well as a selection of some of the hybrids he was most proud of, though at that time they were only identified by Dexter's numbers. These hybrids are most interesting because they show the progression of Dexter's hybrids, from working almost entirely with R. catawbiense types to a shifting over to nearly pure R. fortunei bloodlines.

These hybrids were all planted along Hemlock Hill, and were later added to by the Dexter Study Committee in the 1950's. Donald Wyman, horticulturist at the arboretum, was asked to serve on the committee, and through him the collection acquired a number of the original selections that were made by the study group. These were added to the existing Dexter hybrids on Hemlock Hill, so that today you can see and compare them in the same area.
Whether you care for a casual stroll through the collection for simple beauty or you wish to peruse individual plants for study, a trip to the Arnold Arboretum is a treat for the rhododendron lover.

C.J. Patterson, Massachusetts Chapter member, is plant information officer at the Arnold Arboretum.