JARS v52n2 - Tracking Mr. Fraser's Rhododendron North of the 60th Parallel

Tracking Mr. Fraser's Rhododendron North of the 60th Parallel
Clive L. Justice
Vancouver, British Columbia Canada

At the ARS convention in Oban, while discussing cold hardiness of rhododendrons, what else!, with Björn Alden of Sweden's Götberg Botanical Garden, I mentioned that I would be in Estonia in June/July on a Canadian Executive Service Organization (CESO) project. He suggested I nip over to Finland to see the rhododendrons in the Mustila Arboretum, some 80 kilometers northeast of Helsinki. So I returned to Tallinn, the capital of Estonia, from my assignment in Otepää a day early and took the fast ferry across the Gulf of Finland to Helsinki. We found a taxi driver who knew where Mustila was, and two hours later we arrived at the arboretum. (It is actually 120 kilometers from the Helsinki docks. Luckily, we had contracted for the return trip based on an 80 kilometer distance, and as it had taken all my CESO walkaround allowance money the driver had to take us back to catch the 5 p.m. ferry across the gulf to Tallinn.) I was anxious to know what rhododendrons I would find at this far north arboretum. Finding 'Fraseri' (Fraseri Group) was the prize of surprises.

The sixtieth parallel north runs through the middle of the Gulf of Finland so Mustila is definitely a degree more or less above and is on the same parallel as Oslo, Norway, the southern tip of Greenland, Whitehorse in the Yukon and Seward in Alaska. In climatic terms the Arboretum Mustila is situated in the southern boreal subzone with a growing season of 175 days (temperature above 5°C/41°F). Winter temperatures occasionally drop below -40°C/ -40°F (USDA Hardiness Zone 3). Begun around 1902, Mustila is used primarily to test the hardiness of exotic trees and build a gene bank for breeding and introducing hardy trees to Finland. The arboretum, over the last 60 years, also has been testing the hardiness of rhododendrons.

The tree collection at Mustila is quite unlike any arboretum the writer has visited. A stand of large Siberian larch, Larix sibirica , looked for all the world like deodar cedars, Cedrus deodara ; it must be a magnificent splash of gold in the fall. Of particular interest to those of us from the Pacific Northwest are the 1-meter-diameter ( dbh ) Douglas firs, Pseudotsuga menziesii var. glauca that have the 6-inch-thick bark usually seen only on first growth trees. These trees were grown from seed collected in the Prince George area of central British Columbia in 1931. A surprise for those of us from northeastern North America would be the several 1-meter-plus diameter ( dbh ) American beeches, Fagus grandifoiia , at Mustila. A small maple that caught my fancy was the Siberian Acer barbinerve with shape and habit like a Japanese maple but obviously much hardier. Two vines I did not expect to find growing vigorously on the trunks of trees was Hydrangea petiolaris and even more of a surprise was Actinidia kolomikta with its white and pink blotched leaves growing as a scrambler shrub and tall climber. I had seen this cousin of the kiwi fruit in several gardens in southern Estonia and covering the whole wall of a building in the Tartu Forest Nursery and at the Tartu Botanical Gardens but never expected to see it in Mustila. In 1981 I first saw this vine growing in the wild on Mt. Omei in Sichuan, China. ¹ At first from a distance, I remember, we mistook the white leaves for the bracts of Davidia involucrata ; both occur at the same altitude on Omei Shan. Apparently it's perfectly hardy and been growing in the arboretum for years so must have come from an area of China with a much colder climate - at least 3 USDA hardiness zones. Enough of this dendrology and vine trivia and on to what we really came to see, the rhodos.

Our June 30th visit was in the last two weeks of the blooming period for the rhodos and azaleas at Mustila. Those planted since 1972, mainly new hybrids to be tested for hardiness, are displayed in 10-meter-square open pockets each side of the pathway through the woodland setting of larch, pine, Douglas fir, spruce and birch with lingonberry, Vaccinium vitis-idea , as a groundcover. The rhododendrons, mostly species planted earlier in the first part of the '30s, were more scattered clumps among swaths of ferns under the trees. In a woodland setting like Mustila and at this latitude, rhodos are not as floriferous as we are accustomed to seeing or desirous of obtaining for our gardens, so you find only a few trusses displayed per plant. This paucity of bloom may also be helped along by flower buds freezing over the winter.

At the gift shop, I was able to purchase an English version of the proceedings of the 90th Anniversary Jubilee Symposium held at the arboretum in August 1992, and was surprised to find a paper with the complete history and tracking of the rhododendron introduction and breeding program since the first rhododendrons were introduced into the Mustila woodland. These first rhodos were Seidel hybrids ² from Germany. There was one in bloom beside the well marked rhodo/forest walkabout, looking very much like a Rhododendron catawbiense . I see little difference, but the difference is important in Mustila, as the Seidel's do not suffer as much damage as the true white or lilac Catawbas. This was brought out in the paper given by Marjatta Uosuikainen of the Agricultural Research Centre of Finland in Laukaa, along with a number of hardiness and mortality tables for the Mustila rhodos. In summary, the good news: rhodos at Mustila that thrive are completely hardy and suffer little or no damage or, if damaged, recover. They are: Rhododendron brachycarpum (as ssp. tigerstedtii ) ³ from Korea, R. smirnowii , 'Cunningham's White', and 'Scarlet Wonder'. Among the lepidotes, R. dauricum is a poor flowerer but completely hardy, while R. sichotense (from Amur River area seed in 1976) is hardy but a poor grower. Rhododendron ferrugineum , R. hirsutum , R. concinnum and R. tomentosum (formerly Ledum palustre ) are completely hardy, the latter, of course, as it is part of the forest vegetation in this part of Finland. The bad news: all of the so-called "ironclads," 'Roseum Elegans', 'Nova Zembla', 'English Roseum', 'Caractacus' and Gable's 'Catalgla', lasted only two years. Among the lepidotes R. impeditum died after 14 years, while R. lapponicum , R. polycladum Scintillans Group and R. kotschyi ( R. myrtifolium ) toughed it out over different 17 year periods before giving up. The surprise is with the deciduous azaleas: after 20 years, R. luteum ⁴ and the Gandavense ⁵ hybrids suffer only occasional frost damage, while the Rustica ⁶ hybrids have some yearly frost damage. The biggest surprise of all, however, is Fraseri (Fraseri Group), ⁷ a cross made by George Fraser of Ucluelet B.C. in 1912 between R. molle ssp. japonicum and R. canadense , along with the latter parent species from the bogs of Nova Scotia. Both R. canadense and Fraser's azalea are completely hardy, suffer no frost damage, and have been growing in Mustila Arboretum woodland for over 60 years. R. molle ssp. japonicum , the other parent, suffers regular bud damage at Mustila.

For many years Henry Eddie's Nursery (this was before garden centres), at 41st and Marine Drive in Vancouver, with growing areas up the valley in Sardis and at Steveston Highway and No. 2 Road in nearby Richmond, was the only place in North America that grew Fraser's azalea. I remember purchasing a large plant in the 1960s and having it in the garden for some 15 years. During the latter years of its life, a brittle, thin-barked branch would die each year until finally there were no branches left. I suspect I erred in growing this deep mauve, very floriferous azalea in a rather dry full sun situation; whereas a swampy shaded habitat would probably have been more to its liking, considering that both parents came from low wet woodland habitats. This is certainly the habitat that it has enjoyed in Mustila over more than half a century. I'm sorry we were too late to catch it in flower on our June 30th visit to this "North of 60°" woodland habitat. A photo of its shorter lived but full-sun and more floriferous character in a garden setting will have to suffice for the reader's appreciation of this unusual, one-of-a-kind antique: George Fraser's azalea.

End Notes
¹ Justice, Clive L. "Some Observations on the Flora of Omei Shan, with Reference to Rhododendrons at Different Altitudes." Rhododendron Notes & Records , Journal of the Rhododendron Species Foundation, ed. Judy Young. Vol. 1, 1984.
² Walter Schmalscheidt in Chapter 9 of the new RHS The Rhododendron Story , edited by Cynthia Postan, tells the story of the Seidel rhododendrons. Part of the hardiness of these R. catawbiense , R. smirnowii crosses was that they were grafted onto the roots of R. 'Cunningham's White'.
³ The subspecies epithet honours Dr. C.G. Tigerstedt, who was director of Mustila Arboretum from 1926. He took over from his father Axel Fredrik Tigerstedt, who had founded Arboretum Mustila.
⁴ Rhododendron luteum , syn. R. flavum , from Eastern Europe and the Caucasus Mountains, was used extensively for the understock of the Ghent hybrid azaleas. It was also one of the multi parents of the Ghent azaleas.
⁵ Latin for Belgium, hence referring to the Ghent azaleas.
⁶ "The old name for the Mollis azaleas. There is also a group of double flower Mollis azaleas called the Rustica Flore Plena azaleas.
⁷ The rhododendron hybrid 'Fraseri' was named by Wm. Watson, curator at Kew Gardens and described in the Gardener's Chronicle of 1920. It was pictured in the August 18th, 1923, issue of the Gardener's Chronicle . See: Lillian Hodgson, George Fraser 1854-1939, ARS Journal, Vol. 76, No. 4, pgs. 226-229. The registered name for Fraser's cross of ( R. canadense x R. molle ssp. japonicum ) is Fraseri Group.

Clive Justice, a member of the Vancouver Chapter and a landscape architect, is a frequent contributor to the Journal.