QBARS - v33n3 R. yakushimanum x R. 'Gwilt King'

R. yakushimanum F.C.C. x 'Gwilt King'
Arthur W. Headlam,
Bentleigh, Australia

R. yakushimanum x R. 'Gwilt King'
R. yakushimanum x 'Gwilt King'
Photo by Arthur Headlam
New growth on hybrid rhododendron.
R. yakushimanum x 'Gwilt King'  New growth

Ten to twelve years ago R. yakushimanum was a very much sought after rhododendron in Australia and the F.C.C. form, of which there were very few plants in cultivation, was even more difficult to obtain. Jack O'Shannassy, an enthusiastic member of the Australian Rhododendron Society eventually obtained a small plant of the F.C.C. form, and as soon as it produced its first flower he used it as the seed parent for the cross with 'Gwilt King' ( R. griersonianum x R. zeylanicum ). Seed was set and seedlings were raised and distributed, but as is often the case when very small seedlings are transplanted into different growing media and grown on under different environmental conditions, many plants do not survive.
My small plant was potted on in a mixture of peat moss, perlite and chopped sphagnum moss and all was enclosed in a clear polythene bag and placed in a sheltered position in my garden. Growth was extremely slow, but it eventually started to get away and the first pleasing aspect was the foliage, the dark green leaves up to five inches long by two inches wide carried a deep cinnamon colored indumentum below, whilst the new growth had the usual R. yakushimanum fawn tomentum and as the foliage matured it turned to dark green.
In Spring 1976 at the age of seven years, it appeared to be setting some flower buds, but these eventually finished up as new growth. In Spring 1977 there again appeared what I thought to be three large buds and this time to my great delight they were in fact flower buds. The first bud showed color on November 1, it was 45B on the R. H. S. Color Chart (Post Office Red), and as the flowers opened they gradually faded to R. H. S. Color Chart 54A (Spinet Red), fading to paler pink and eventually white in the center of the flower with light spotting on the upper lobes. It carried 18 flowers to the truss and the flowers measured two and three quarter inches across the lobes.
To me its attractions are its dark green foliage, its cinnamon colored indumentum, its typical R. yakushimanum new growth and finally, the attractive flowers, first Post Office Red, through Spinet Red and finally when the flowers have been open for some two weeks they still carry a slight pink flush. In an endeavor to eliminate the fading, which appears to be common with many R. yakushimanum hybrids, it has been back crossed with R. griersonianum , thus bringing this species twice into its lineage; only time will tell if the results come up to expectations.
From enquiries made, my plant appears to be the one and only survivor from the batch of seedlings distributed, and the seed parent died the following Summer after the cross was made.
Naming the hybrid has been a problem, the obvious and appropriate name would have been 'Yaku King', but this has already been used, so in the meantime, because of the attractive indumentum, it has been temporarily labeled Yakumentum.