This past year I have been working with and sharing research with Dr Barrie Machin a chrysanthemum breeder for many years and holder of the RHS Gold Veitch Memorial Medal for his work.
We are studying the species to obtain a greater understanding and to enable breeders to produce new hardy plants.
Dr Machin at the Wisley Field Trials April 2012
HARDY BORDER CHRYSANTHEMUMS
Dr Barrie Machin
The Chrysanthemum sub committee of the RHS is finishing a three year hardiness trial of border chrysanthemums. In 2012 it has been proved that 100% of them are hardy, because all of them survived the very cold spell in November and December 2010 (the air temperature at Deers Farm went down to -17 ?C on 21st December).
Although the height of individual varieties varies from 40-100cm (16" - 40") all could be easily accommodated in a garden border, with flowering according to variety extending from early July to late November. The best range will be demonstrated in a border at Wisley Garden in future years.
The history of the breeding of these hardy chrysanthemums is fascinating and due to the hard work of Mrs Judy Barker who holds the National Collection of Hardy Chrysanthemums® with Plant Heritage, and who has spent countless hours researching the background of each variety, much more information is available to explain the development of these plants through the ages. Of the 128 varieties being grown in the trial Mrs Barker has supplied 97 cultivars from her collection of border chrysanthemums.
Chrysanthemums were first talked about in China in the time of Confucius about 500 BC and gradually spread from there to Korea and Japan where many forms were developed from about 900 AD for the next 1000 years. It was not, however, until 1789 that a late flowering, loosely incurving Chinese variety called 'Old Purple' arrived in Marseilles and spread rapidly northwards through France and Holland to England, where it became very popular.
However, 'Old Purple' was a late flowering variety and required glasshouse protection to flower well. Varieties which could flower before the frosts only arrived in Europe spasmodically during the 1820's to 40's, both from China and Japan via intrepid plant hunters such as Robert Fortune. He brought in the Chusan daisies from China (actually pompons) which were especially admired by the French, also a few late September, October flowering incurves and decoratives which had been developed in Japan. Even so, the latter group did not have a long enough flowering period outdoors. The French breeders, e.g. in particular M. Lebois, tried hard to create earlier flowering types, which would mature outdoors well before the important All Saints Day (1st November).
They very gradually extended the flowering season, so by the 1850's growers in England were using them and they were classified as 'Early Flowering' varieties. At the same time these early varieties found their way across the Atlantic to the eastern parts of the USA often via French sailors. In America the early flowering varieties generally became known as 'Garden Mums'.
By this time 'Old Purple' and other chrysanthemums had been named C. morifolium by the French botanist Ramatuelle. Most of the earlier flowering types were fairly hardy and if well protected, could withstand average winter climates but they were still somewhat lacking in form and colour.
Meanwhile plant hunters were still bringing interesting chrysanthemums westwards and in 1905 E H Wilson collected a species in Korea for the Arnold Arboretum near Boston. It was introduced to American growers as C. 'Autumn Glory' and enjoyed limited success.
After some years of flowering, C. 'Autumn Glory' was given to Alex Cumming, a chrysanthemum breeder who had recently started his own nursery. (Bristol Nursery in Connecticut). He admired the plant's characters and called it Chrysanthemum coreanum and in 1928 began to use it in his breeding programme. He described it as his "Korean daisy" which was vigorous well branched three to four feet tall, floriferous with two inch single flowers, alabaster white aging to carmine pink and very hardy. He bred it into two lines of his own double crosses and after a series of inter-crosses between the best seedlings of both lines introduced a range of Korean hybrids. The first of these were singles named after the planets e.g. Mars and Mercury.
Gradually both doubles and pompons were released and were sent to England where they were released by Wells of Merstham from 1936 onwards. Indeed a yellow pompon Korean was named Jante Wells which is now flowering in the trials.
A few years before the Cumming Koreans were being introduced to England a very significant event occurred in N Wales. In 1929 in the Happy Valley Gardens in Llandudno an odd plant flowered amongst a batch of rock garden chrysanthemums sent from an estate near Glasgow. It was thought by Dr Stapf to be C. erubescens and was exhibited at Kew gardens in that name in 1935 winning an award of merit.
John Sealy, the botanist at Kew, decided that it was not C. erubescens but it was also different from every other chrysanthemum species known to man. Sealy most closely allied it to C. zawadskii v. sibiricum but it was much improved in each of the latter's characters being taller with more luxuriant growth with coarser leaves and larger flowers. i.e. more vigour in each character. It was different from the Koreans by having leaves which were more lobed and the flowers were even more scented. He, therefore, thought it should be considered as a new species and called it C. rubellum.
Amos Perry, a chrysanthemum grower and breeder from Enfield, having seen C. rubellum in the Kew trials, decided to use it in his breeding programme. Crossing C. rubellum with his own and other leading early varieties of the period he produced a new, improved range which he called Rubellums. Some of these such as C. 'Clara Curtis,' C. 'Lady in Pink,' and C. 'Paul Boissier', are in the trial and still growing well.
Rubellums and Koreans are similar in habit, vigour and hardiness and it is almost impossible to distinguish between them in the trial. It is said that amongst the original varieties in each group Rubellums have a more spreading rootstock than the Koreans and also have a more pronounced scent, said to be inherited from their ancestor C. indicum..
One especially important fact has emerged from historical notes uncovered by Judy Barker.
Amos Perry's son Gerald had a plant of C. zawadskii in his garden which produced an improved mutation. This mutation was compared to two sources of C. rubellum and found to be identical! In his researches to correctly identify C. rubellum John Sealy found that the original C. zawadskii had been discovered in what is now Slovakia (near the Polish border) in 1831 at approximately 50 ?N latitude. Other virtually identical chrysanthemum species had been discovered along the same latitude right to the far east of Asia and then south into Korea, China, and Japan. Information held in Geneva (De Candolle) showed that although only slightly different to C. zawadskii in leaf characteristics they had been given different names such as C. sibiricum v acutilobum. Sealy decided that since C. zawadskii had been named first all these similar types should be regarded as varieties of C. zawadskii.
Going back to Sealy's original conclusion about C rubellum, he was wrong to have given a new species name to what was obviously a more vigorous sport of C. zawadskii v sibiricum. It should have been named more correctly as C zawadskii v sibiricum robustrum.
Had Sealy been working 35 years later he would have realised the true facts. In the 1970's myself and other breeders had to use a two stage breeding programme to protect our varieties.
Firstly, a very good seedling was produced but not released. Then mutation breeding took over for another three years using gamma or X-rays to induce mutations. The colour sports and mutants for extreme vigour were collected and only then was the new family released to the trade. This prevented other breeders, especially Dutch ones, exploiting the genotype of the new seedling to earn royalties. Often a more vigorous genotype was released rather than the original but less vigorous parent.
All this means that Amos Perry was actually crossing C. morifolium (the early florist's double chrysanthemum) with the very hardy C. zawadskii variety to produce the so called Rubellums.
Over in America Roderick Cumming had written in his 1964 book that the Korean daisy that his father had used to produce the Koreans was not C. coreanum but C. sibiricum which we now know is actually C. zawadskii v. sibiricum. So it is now apparent that the two breeders were actually making very similar crosses on both sides of the Atlantic, at more or less the same time to produce both the Koreans and Rubellums. It is easy to understand why they are similar in most main characteristics.
The hardiness of both Koreans and Rubellums is mainly derived from the species C. zawadskii varieties which developed over a very long distance across Europe and Asia at 50 ?N latitude. This would not have been too far south of the northern ice caps during the Ice Ages, and they would have endured a wide range of soil and moisture conditions, and some very low winter temperatures.
The very last piece of the jigsaw arrived from my old Japanese chrysanthemum breeder friend Dr. J Kawata in June 2011. He sent me a paper, by Dr Fukai, stating that although the true origin is still unclear the consensus of Japanese studies of chrysanthemum species arrived at the opinion that C. morifolium was most probably developed from crosses between C. indicum (China) and C. zawadskii v. latilobum. Both Cumming and Perry were actually backcrossing C. zawadskii to its original and most hardy parent and therefore concentrating the genes of C. zawadskii in their progeny. This is probably why many of the varieties in the border chrysanthemum trial are extremely hardy although the exact degree of hardiness remains to be discovered.
However, the main conclusion to draw from all this newly gathered information is that it presents a wonderful opportunity for some meaningfull further breeding of border chrysanthemums. About half of Judy's varieties in the trial have been shown to be worthy of awards. Also, and even more important, roughly half of these award winning types appear to be partly or wholly resistant to white rust, at least during the 2011 season.
After this year of flowering Judy will list the best varieties and say where they can be obtained. It will then be up to young keen chrysanthemum enthusiasts to pick up the baton and make the crosses that will provide attractive, hardy and disease free border chrysanthemums of the future. I trust that this opportunity will not be missed.
I also note, from the NCS yearbook 2011 (p 42) that Dr Alan Reynolds brought back two samples of new hardy chrysanthemum species from Tibet and Nepal during the 1970's. One of them had been growing at an altitude of 7000 feet. Chris Riley used them in his crosses to produce his Pennine singles. What is the betting that these two species were C. zawadskii types?
Judy Barker National Collection Holder registered with Plant Heritage www.gardenchrysanthemums.org.uk