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The genus Rhododendron
by Peter Hicklenton
November 15, 1999

Over a period of nearly 4 decades The Kentville Agricultural Centre located in the beautiful Annapolis Valley of Nova Scotia has assembled one of the most renowned collections of rhododendrons and azaleas in Atlantic Canada. Set in a natural bowl and framed with mature hardwood trees, these magnificent plants attract thousands of visitors starting early June, and continuing until the last blooms fade sometime in early July. The first rhododendrons were planted some 75 years ago by the first superintendent of the Dominion Experimental Farm, Dr. Saxby Blair, but it was not until 1958 when horticultural pioneers Dr. Donald Craig and Mr. George Swain began clearing the sloping land below the experimental farm that collection, breeding and selection were begun in earnest. Today there are hundreds of plants from all over the world, and a significant collection of rhododendrons and azaleas, products of the ornamental research program at Kentville.

The genus Rhododendron which includes the azaleas, is a most remarkable group of plants. The genus comprises over 900 species, most of which are frost tender and grow only in tropical and subtropical climates. Several grow well in the northern sections of the United States, China, Korea and Japan and a few are found in Eastern Europe where the climate is similar to that in Atlantic Canada. Some species may be found in the Arctic, in tropical rain forests, on mountain tops, in valleys, and on plains. The greatest number are concentrated in the hills and valleys of western China (Yunnan and Szechwan provinces) and Tibet. In these areas, many species cover the countryside for miles. In North America only 25 native species are found.

In flower and form these plants range from the tiniest alpines with veil-like florets smaller than a dime in diamter to towering trees of over 18 m high with leaves 0.9m long and trusses of flowers larger than the head of an adult male. The range of colour is even greater than that found in the rose. At Kentville, we have examples of many of the principal rhododendron and azalea groups and are consistently adding to our collection.

The first crosses in a program designed to breed improved rhododendrons and azaleas for Atlantic Canada were made at the Station in 1958. Between 1960 and the late 1980s , many thousands of seedlings were produced from crosses between species, varieties, and seedling selections. Many of them have flowered at Kentville in field plots or nursery beds and the best have been named and released to the public.

The first new rhododendrons were released as cultivars in 1973 and were named Acadia, Grand Pr‚, Evangeline and Gabriel. The names chosen by plant breeder, Dr. Don Craig, honored the strong Acadian heritage of the Annapolis Valley and commemorated Longfellow's famous poem Evangeline which was set in the village of Grand Pr‚, some 10 miles east of Kentville. Unfortunately two of the names were later found to be duplicates of cultivar names already in use and so Acadia became known as Cornwallis and Evangeline as Fundy. Of these 4 original selections, two (Gabriel and Grand Pre) were the progeny of crosses made several years earlier by the late George Swain. Gabriel is a semi-compact plant suitable for planting in relatively confined spaces. Masses of frilled flowers are pink and borne in compact trusses well above the foliage. Grand Pre is a quite unusual and highly attractive rhododendron with distinctive, elliptical leaves and profuse bell-shaped flowers formed in loose clusters above the foliage. Like Gabriel it is compact and very suitable for foundation plantings. Cornwallis and Fundy on the other hand are best suited to a more expansive site where the large, pleasantly scented flowers can be viewed to full advantage. Both Fundy and Cornwallis were selected by Dr. Craig from seedlings derived from open pollinated R. fortunei (Cornwallis) and from a cross between R. fortunei and R. smirnowii (Fundy).

Continuing the Acadian theme, in 1975, Dr. Craig released Bellefontaine another seedling from the R. fortunei and R. smirnowii cross which produced Cornwallis. Another large plant, Bellefontaine features dark green foliage and large, pleasantly scented, rose-pink flowers which open very early in the Spring.

In 1979 and 1981, respectively two more rhododendrons were released: Minas Maid and Minas Snow, both resulting from crosses made by G.S.Swain in 1966. As the name implies Minas Snow bears a pure white, 5-lobed flower some 7 cm in diameter and 5 cm long. Deriving its hardiness (flowers hardy to at least -26C) from R. yakusimanum and its pure white colour from the cultivar Cunningham's White, this plant has proved popular throughout the Maritimes and elsewhere in North America. The first red-flowered rhododendron to be released from the program, Minas Maid also grows as a relatively compact shrub making it quite suitable for small gardens and confined spaces.

By the early 1980's the progeny of crosses made by Dr. Craig in the 60's and 70's were large enough to have flowered consistently, allowing him to make some new selections. In 1983 Minas Rose and Minas Peace rhododendrons were released, together with the first deciduous azaleas Minas Princess, Minas Gold and Minas Flame. The two rhododendrons continued the theme of a floriferous, compact growth habit established with Minas Maid. Minas Peace ([R. catawbiense album x R. degronianum] x R. yakusimanum) is characterized by a thick indumentum on the underside of the leaves and medium-sized red-pink flowers with a particularly delicate texture. Minas Rose ([Nova Zembla x R. yakusimanum] x [R. catawbiense x Elizabeth]) on the other hand displays striking red-purple flowers up to 11cm in diameter and 9 cm long borne above the foliage. The 3 azaleas exhibit the amazing range of colour which is a feature of this group. Minas Princess (selected from the progeny of an open pollinated Ghent hybrid azalea) displays a mass of delicate red-pink flowers in June, while the very floriferous Minas Gold and Minas Flame bear bright yellow and orange-red flowers, respectively. Flowers of Minas Gold (Golden Dream x R. luteum) have the added characteristic of a pleasant, sweet scent reminiscent of the R. luteum parent). Minas Flame (Gibraltar x Balzac), adopts a very upright, compact growth habit making it suitable for planting close to buildings. The spectacle of the abundant, flame-orange/red flowers in mid June is quite dazzling.

The last rhododendron to be released from the breeding program satisfied the long quest for a hardy, yellow flowered rhododendron which would bloom reliably and withstand the rigours of a Maritime climate. Rhododendron G.S. Swain was named in honour of the late George Swain, a member of the Kentville Research Station staff from 1957 to 1967 and a significant contributor to the ornamentals program. The cross (Goldsworth yellow x (R. Catawbiense album) x Theresa) which produced the plant was made by Dr. Craig in 1970; G.S. Swain was selected from a group of 170 seedlings which were carefully evaluated for 15 years. Flowers are a bright ivory-yellow and are quite striking against the dark-green foliage of this sturdy, upright shrub.

The objective of providing hardy, floriferous plants to enhance and beautify Canadian gardens has always been the driving force behind the ornamentals program at Kentville. While research in this area is no longer taking place at Kentville, the legacy of some 40 years of plant collection, evaluation and selection remains. A significant effort has always been devoted to breeding new rhododendrons and azaleas, but an equally important part of the program has been the introduction of plants from other parts of the world for evaluation under northern conditions. Not every introduction was successful but today the number of plants which continue to thrive on the grounds of the Agricultural Centre attest to the fact that many exciting specimens can be grown in our relatively harsh climate. Among the groupings which you will find among the hardwoods and around our lily pond are the Knap Hill hybrid azaleas, products of some 200 years of hybridization, Rhododendron carolinianum, a native of the mountains of Tennessee and the Carolinas, the early -flowering Rhododendron mucronulatum, and in contrast the very late- flowering Rhododendron bakerii which may still be in bloom in early July, Ghent azaleas and Mollis hybrid azaleas. Full descriptions are available at our web site: http://res.agr.ca/kentville/pubs/rhodo.htm along with colour photographs of the azaleas and rhododendrons released from the ornamentals program. But a virtual tour is no substitute for the real thing, so plan on visiting our Annapolis Valley site soon. The annual Kentville Rhododendron Sunday, held generally on the second Sunday in June (but this year on June 15), is an ideal opportunity to see our collection in all it's Spring glory - the colorful display as you wind up the main drive will make you feel that the trip was well worthwhile.

Peter Hicklenton

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