QBARS - v11n1 R. orbiculare

R. orbiculare
By Alleyne R. Cook, Vancouver, B.C.

The late Lord Aberconway in an article in the 1947 Rhododendron Year Book gave a list of ten species which he considered to be the most useful garden plants that had come to him from the seeds gathered in the wild by the various plant collectors. The first one on his list is R. orbiculare . This is a rhododendron with a perfect habit, very hardy, rose colored flowers and the most unusual foliage.
It is very seldom that R. orbiculare is seen in gardens in this country, and never have I seen it listed in any catalogue. Yet it is my opinion that as a flowering ornamental shrub there are very few finer plants, and as a foliage plant there is no rhododendron that can compare with it. Those people who do grow it do so as much for the foliage as for the flowers and these two outstanding features when combined with its dome-like habit and hardiness puts it in a class of its own.
It is curious that even though it's perfectly rounded foliage suggests the R. thomsonii series, R. orbiculare has been placed in the R. fortunei series. The color of this foliage I have noticed varies considerable with its location in the garden; where it is in semi-shade they are a much darker green than those receiving a considerable amount of sunlight, these later tending to take on the yellow-green shade common to plants of R. 'Pink Pearl'. This difference in shading is not uncommon amongst rhododendrons, for many of the species and pedigreed hybrids are woodland plants and broken sunlight helps improve their general appearance.

R. orbiculare has seven rose petals joined to make a pleasing bell shaped flower. It is these seven sections that place it in the R. fortunei series. The color "rose" is the trade expression for a bluish pink, for the latter is an unpopular color and the former makes the plant easier to sell. It is however a pleasing shade. The truss varies between 7-10 flowers. The finest flowering plant I have ever seen was in a border at Bodnant (Fig. 10) where a bush about five feet high was one solid mass of bloom. It was I noticed growing in full sun and further observation of the amount of bloom carried on plants in shaded positions leads me to think that those in full sun produce far more flowers. However, I have never had the opportunity to examine the amount of flowers on any one bush over a period of years which is the only way to judge the quality of any plant. It may have been a particularly good year for the Bodnant plant and poor one for the others.
The third factor in its favor is its habit. In a location in the garden where it does not have to compete with other plants and where it does not become drawn it forms a perfect mound of unbroken green. In the wild it is said to grow to nine feet but the largest plants in England are six feet high and 13 feet through. All the plants I have seen have been about 5-6 feet high, and the same in diameter, so it seems that they grow in a mound form until a certain height is reached and then increase in width.
Finally there is the question of hardiness. At the Royston Nurseries on Vancouver Island, probably the coldest area where rhododendrons are grown on the Pacific Coast, small unprotected plants came through last winter without a sign of damage. If any part of the plant would be hurt it would be the bloom, for coming in April they could be damaged by a late frost.
There is only one hybrid of R. orbiculare on the market, and this is no improvement on either parent. This is R. 'Temple Belle' the cross with R. williamsianum . The rounded leaves are retained, the flowers are in no way improved though it grows lower and wider and it certainly flowers no better nor any earlier in life. There seems no point in growing a hybrid that is no improvement on its parents and it is my opinion that R. 'Temple Belle' is not a better plant than R. orbiculare .