1. Germplasm Conservation of Tree Peonies – An Urgent and Followed Effectively Subject

Tree peonies, or Mudan, have been cultivated for more than 1,500 years in China, where they are indigenous. They were introduced into Japan about 1,200 years ago and into Western countries following the first introduction at Kew in 1787 by Sir Joseph Banks. As prized ornamental plants, tree peonies have made a great contribution to gardens and, at present, more than 1,000 cultivars composed of various cultivar groups and suited to different climates have been developed in different regions/countries around the world. However, these cultivars undoubtedly use only part of the wild germplasm resources endemic to China and wild species still have very great potential for breeding improved cultivars.

Records in ancient Chinese literature shows that tree peonies had a relatively wide wild distribution in the early stage of their introduction into gardens. When both the wild and cultivated plants were collected from various areas and concentrated in rural places like Luoyan and Changan, the ancient capitals of China, repeated crossing and selecting were performed on the basis of richer gene sources and led to the emergence of many cultivars as representatives of these wonderful flowers. As tree peonies were respected as “the King of Flowers” and developed into an essential element of Chinese cultural heritage, their cultivation and use as ornamental plants received great attention. On the other hand, as the cortex of tree peony roots is the chief source of “Danpi”, an important traditional Chinese medicine, the wild plants have experienced sustained destruction to such an extent that their distribution and number in natural habitats has became less and less and even disappeared in some areas. Nowadays, the industrialization of China is bringing about not only changes of ecological environment in the regions where tree peonies occur but also is making it easier for local people to collect the roots of tree peonies to sell. Therefore, the existence of tree peonies in natural habitats is being threatened more and more seriously than ever before and all species must be regarded as being in the danger of extinction and are listed as the endangered or rare plants by the Chinese government. The active conservation of wild tree peonies has become an urgent matter.

With the initiation of bio-diversity conservation in China and the requirement of the commercial flower industry, tree peonies have received an unprecedented level of attention in China from botanists and horticulturists in recent decades. Particular mention should be made of the two expeditions on wild tree peonies in China by Dr. L.G. Osti, vice-Chairman of the International Dendrology Society, which had a significant influence and promoted interest among Chinese researchers, institutes and government departments concerned with tree peonies. There has been effective research on different aspects of conservation and use of wild resources. To our knowledge, at least 8 botanical or horticultural institutes, 4 universities and 4-6 larger nurseries, including a few outstanding institutes or universities supported by the National Science Fund or other funds of government departments, have been involved in investigation of wild tree peonies. Not all these investigations have continued to the stage of practical remedial measures and it is important that the various conclusions are

Table. Species and wild distribution of tree peonies in China

¹Distribution Region of Loess Plateau and Qin-Ba Mountains;

²Distribution Region of Heng-Duan Mountains

collated and used for this purpose. Among the most notable recent achievement are the discovery of some new species and the identification of the wild distribution of each species. These show the encouraging results that both the diversity and the distribution areas of wild tree peonies resources are greater than was thought in the past (Table). Some species, such as Paeonia rockii, P. lutea and P. potaninii , have abundant intraspecies varieties or forms useful for breeding and selecting new types of cultivars. Biological studies have confirmed that, except for the artificial destruction for collection of roots, the causes endangering the life of wild tree peonies mostly come from their inherent biological characteristics that are unfavourable for natural reproduction in a changed ecological environment. However, some experience and knowledge in the introduction and acclimation of wild plants has been accumulated. Some species were successfully introduced into the cultivation environment in Lanzhou, the capital of Gansu province in Northwest China, and Kunming, the capital of Yunnan province in Southwest China, but their growth is still under observation. But from these recent advances of general introduction and domestication, it is evidently difficult or even impossible to realize the germplasm conservation. In total, the work of the past few years confirm that, if tree peonies are to be conserved in natural habitats, an effective system to propagate them must be developed specifically for the purpose of conserve wild germplasm. .

2. Natural Reserve – Bases for Conserving and Propagating Tree Peonies in Natural Habitats

By climatic, floral and other natural features, wild tree peonies constitute chiefly two distribution regions: (1) Distribution Region of Loess Plateau and Qin-Ba Mountains and (2) Distribution Region of Heng-Duan Mountains (Table). All species of Suffruticosa group (Subs. Vaginatae) are distributed in the region (1). And it is from these species and this region that Chinese traditional cultivars originated many years ago. The other species of the Delavayi group (Subs. Delavayanae), are distributed in the region (2) and have significantly contributed to the improvement of tree peony cultivars after being introduced to France and America. This project will choose the most suitable places in the two distinctive distribution regions as the conservation bases of two groups of tree peony species. The places will be located in the national nature reserves established by the government and they actually include the natural habitats of most relevant species.

As much of the wild populations were destroyed and numbers of individuals in the populations decreased, the wild distribution of tree peonies is now relatively fragmentary in almost every natural habitat so that natural reproduction is not normally adequate to maintain existing populations and will not occur every year. Thus, it will be important for the re-establishment and recovery of natural reproductive system to collect and concentrate certain quantities of plants in the conservation bases. In plots devoted to each species, the plants will be propagated by such traditional methods as seed germination, division, layering and even grafting based on the distinct reproductive traits of species, which we have observed and studied in detail in the natural habitats. When it is clear that a colony of plants of particular species has increased to the extent that the natural reproduction system re-established then the conservation bases can begin to supply specimens botanical gardens, researchers and breeders around the world, and in due course even for commercial markets. An equally important development will be that the conservation bases will act as technique training bases to supply training and guidance of cultivation and propagation techniques. This will enable local people in the wild distribution regions to grow tree peonies for medicine use without damaging wild population. A particularly important part of the project will be to assess these species and forms for which conservation measures are most urgently needed and remedial measures for the most endangered species will be undertaken without delay.