Preface

　In April 1600 the Dutch ship De Liefde was cast up on the coast of Bungo Province, Kyushu, Japan. Although Japan had little contact with the Netherlands at the time, Ieyasu Tokugawa, the founder of the Tokugawa Shogunate Government, provided air to the crew, including its English navigator, William Adams. Adams was nursed back to health and eventually became an advisor to Ieyasu Tokugawa in matters dealing with Europeans. For both the Dutch and the Japanese, however, the landing of De Liefde was to mark not only the beginning of a monopoly in Japan's trade with the west, but also the start of an unprecedented period of friendship between the two countries that continues to the present.

　The Kyôhô age, starting in 1716 under the 8th Tokugawa Shogun, Yoshimune Tokugawa, began a new epoch in Japanese-Dutch relations. At that time the Japanese approached the Dutch with the hope of acquiring new technical skills in medical practice and natural products from the West. Although the interchange developed slowly and steadily, it did not flourish until one hundred years later when on 8th August 1823 Philipp Franz von Siebold (1796-1866) arrived in Japan. At the time Siebold was only 27 years old.

　The Netherlands had lost their colonial territories in east tropical Asia in a war with England after the Napoleonic Wars. When the Netherlands regained their territories in east tropical Asia from England in 1814, they set about to improve trade with Japan. To strengthen the already close relationship between the two countries, and to increase their repute among the countries of Europe, the Dutch promoted scientific surveys and the collection of natural history objects and products. They set about to obtain more accurate information than was then available, especially concerning nature, human history and the culture of Japan, and to learn more about the various personalities of the time. Siebold's deep interest in botany and the natural sciences, which made him well qualified for the task at hand, as well as for his medical practice, was very much respected by the Japanese.

　Siebold's enthusiasm for his charge, his deep interest in all things Japanese, his willingness to share his knowledge of medicine and science with his Japanese students, and the knowledge he sent back about a country that was scarcely known in the west, has had a lasting impact both in the west and in Japan. Siebold discovered two important things about Japan; one was Japan's advanced state of horti-culture and the other was that Japan was skillfully utilizing its natural resources through a well organized system of recycling and sustainability. Life even in the countryside was not so much rich as thrifty. Daily needs were satisfied by using a great variety of wooden tools and utensils, and even houses were constructed from a diverse range of plant species.

　Japan has been gifted with many attractive wild shrubs and numerous herbs with beautiful flowers. The Japanese people, especially those living in the country-side, had carried many of them into cultivation in their gardens. After observing these ornamental plants, Siebold developed a plan to change European gardens by utilizing Japanese plants. In the early 19800s the gardens of Europe suffered from a paucity of attractive ornamental plants, and many of the plants that could be grown lacked showy flowers. Although numerous exotic plants had been introduced into Europe, they were mostly from tropical regions and difficult to cultivate out of doors in the European climate. Siebold reasoned that since Japan's climate was temperate in nature, many Japanese plants might be hardy in the gardens of most European countries. His plan was dependent on the climatic similarity between Europe and Japan.

　After returning to the Netherlands, Siebold made an effort to introduce Japanese wild and ornamental plants to European gardens. With Dr. Blume, director of the Rijksherbarium, and other persons, Siebold established the Koninklandsche Maatschappij tot Aanmoediging van de Tuinbouw (the Royal Netherlands Society for encouraging Horticulture). To meet the society's goal of introducing more plants from Japan, they dispatched several collectors, including Heinrich Büerger, Jacques Pierot, Carl Julius Textor, and Otto Gottlieb Johann Mohnike. The results of their efforts are obvious. It would be difficult to imagine the gardens of temperate Europe and North America today without ornamental plants from Asia, the origin which date back to Siebold's early vision.

　At the start of the 21^st Century, biogeographical relationships and the phylogeny of the angiosperms are among the hottest topics in biology. Although several authors had mentioned the similarity of many Asian and American plants, it has often been stated that Asa Gray was the first to focus scientific attention on the close relationships and wide disjunctions of many eastern Asian and eastern North American plants. Even now, 150 years later, this topic attracts more attention than at any time in the past. It is interesting to note that Gray's first paper on the topic, published in 1842, and which focused his attention on Asian-American plant relationships, was a review of Siebold and Zuccarini's Flora Japonica. It is interesting to speculate on the focus of 21^st Century research had Siebold not lived in Japan in the early 1800s.

　To commemorate the four hundred years of friendly relations between Japan and the Netherlands, the University of Leiden and the National Herbarium of the Netherlands donated several hundreds of botanical specimens collected by Philipp Franz von Siebold and his successors to the University Museum, the University of Tokyo, in 2000. To mark the momentous occasion, the University Museum decided to undertake botanical and mineralogical studies on Siebold's contributions and to stage an exhibition on Siebold and his collections, especially on their value to science in the 21^st Century.

　In 2003, the exhibition “Siebold in the 21^st Century” was held at the University Museum. Collections and artifacts gathered during Siebold's time spent in Japan were displayed. The exhibition, organized by the University Museum, the University of Tokyo, and Leiden University, highlighted the contributions of Siebold, directly and indirectly, from the time of his visit to Japan in the early 1800s to the 21^st Century. In conjunction with the exhibition, a symposium entitled Botanical Collections of Philipp Franz von Siebold and His Successors and Present Days was held at the University Museum on 28 November 2003.

　This volume contains four papers presented at that symposium. Two papers, one by Ohba, Akiyama and Thijsse and the other by Thijsse, appear here in greatly expanded form. The paper by Thijsse is the first complete catalog of the Herbarium Japonicum Generale, which comprises the botanical collections of Siebold and his successors, including collections made by several Japanese herbalists of the Edo period. The papers by Ohba, Akiyama and Thijsse is essentially a taxonomic revision of all of Miquel's taxa described from Japan based on the collections of Siebold and his successors. Papers by Pieter Baas, Shuichi Noshiro and David Boufford will be published in a forthcoming volume or elsewhere. The paper by Chou Wen-Liang will be published in the Japanese Journal of Botany.

　We hope that this volume will not only summarize the symposium, but will also provide prospects for further botanical work, whether utilizing or not the collections of Siebold and his successors.