German physician and natural scientist whose life's work was based on eight years spent in Japan while the country was closed to the outside world. Recognised for introducing Western medicine to Japan, Siebold also made large collections of plants and animals in the country, discovering a great many taxa new to science.

Siebold was born in Würzburg and followed his father into the field of medicine. Graduating from the University of Würzburg in 1815, he went on to train as a doctor of medicine and after qualifying in 1820 practised in Heidingsfeld. His appetite for exploration may have been sparked by Alexander von Humboldt's account of his travels in South America, which Siebold read as a student. A family friend invited him to Holland, where he joined the military as a doctor in order to gain passage to the Dutch East Indies. Successful in his aim, he reached Batavia (Jakarta) in February 1823. While recovering from a mild illness he was given a bed at the residence of the governor-general, Baron van der Capellen, where he met the head of Buitenzorg Botanical Garden, Caspar Reinwardt. Both the governor and Reinwardt were impressed with the erudite doctor, who shared their keen interest in natural history.

Siebold was subsequently posted to the Dutch trading post of Dejima, Japan, as resident physician and scientist. He arrived at the island, just outside Nagasaki, in August 1823, having had a lucky escape from drowning while at sea during a typhoon. Once in Dejima he gained favour with the Japanese authorities after successfully treating a senior local officer. In recognition he was permitted to leave the trading post (to which westerners were usually confined under the isolationist policy in force) and attend to patients in the greater area. This also gave him the freedom to make natural history collections, and in 1824 Siebold published his first account of the country's flora and fauna. In 1825 he was appointed two assistants, the pharmacist and mineralogist Heinrich Bürger (who would become Siebold's successor) and painter Carl de Villeneuve. He also became attached to a local woman, Taki Kusumoto, though they were not permitted to marry by law. Their daughter, Oine, was born out of wedlock in 1827.

Siebold established a school, the Narutaki-juku, at his home, where he imparted his medical knowledge and taught Japanese students the Dutch language. The students also helped with his studies of the Japanese flora and fauna. This research became his real focus and as well as assiduously gathering large numbers of specimens Siebold planted a botanical garden of more than a thousand native Japanese plants at his home. During his long sojourn in Japan, he also amassed a significant collection of ethnographic objects, many of them presented to him as payment in kind for his services as a physician.

Despite his zealous work as a naturalist, physician and teacher, Siebold was perceived as arrogant by the Dutch authorities and was recalled to Batavia in 1827. He was granted a reprieve, however, after the ship sent to collect him was hit by a typhoon, a storm which also damaged Siebold's Dejima garden. The ship was repaired, but departed Nagasaki Bay loaded only with Siebold's collections, not the man himself. It would be a further two years before he was ejected from his position in the country, at the behest of the Japanese rather than the Dutch. Siebold's expulsion in 1829 came as a result of his obtaining maps of Japan and Korea, which was strictly forbidden by the Japanese government. He had procured the documents while visiting the royal court in Edo, and when found out was accused of high treason and spying. On his release from house arrest in 1830 he travelled back to Java, where Buitenzorg Botanical Garden took delivery of 2,000 living plants he had cultivated, as well as smuggled seeds of Japanese tea plants, while the botanist sailed onwards to Holland. He would spend the next thirty or so years arranging his scientific collections and writing works about all aspects of his experience in Japan.

At the time of Siebold's return to Europe Belgium seized independence from Holland, and the doctor hastily retrieved collections he had deposited in Antwerp and Brussels, removing them to Leiden, where he settled. The Siebold herbarium at Leiden remains one of the earliest and most significant collections of Japanese plant specimens, containing about 12,000 items. He left his living plants at the University of Ghent, contributing to the city's horticultural fame. Siebold saw these plants once more in 1841, when the university presented to him specimens from every plant he had originally sent there.

Siebold's expertise in Japanese matters was quickly rewarded with a royal appointment as an advisor in Japanese affairs and in 1842 with a peerage. The next decade was filled with work on his various collections and writing about the country, still effectively closed to foreigners, in which he had spent eight years. He published his encyclopaedia-like observations of Japan's people and geography in 1832 under the title Nippon, with a further six volumes on the subject appearing over the next 55 years. He also co-authored a survey of Japanese literature, Bibliotecha Japonica (1833-1841). Zoologists studied his collections of animals to produce the series Fauna Japonica (1833-1850), while Siebold himself worked with Joseph Zuccarini to compile his Flora Japonica (completed after his death by F.A.W. Miquel), which established Siebold's name in botanical history. His private museum of ethnographic items, meanwhile, formed the basis of Holland's National Museum of Ethnology and his natural history collections formed an important part of the National Natural History Museum. The British Museum also received many artefacts from Siebold's private collection after his death and the St. Petersburg Royal Scientific Academy acquired 600 of the botanical plates for Flora Japonica.

As a well-known advisor on all matters Japanese, he was permitted to return to the country 30 years after his deportation, staying for three years (1859-1862) as a kind of ambassador, but unable to carry out much scientific work. He then settled back in his hometown of Würzburg, disillusioned that his services were no longer in demand. He is nevertheless remembered in several museums, including the Siebold Memorial Museum next to his former residence in Nagasaki. (Indeed, Siebold is revered in Japan. A 1926 biography by Kure Shuzo was translated from Japanese into German in 1996.) Siebold introduced many plants from Japan to European horticulture, including hostas, the Japanese larch (Larix kaempferi Fortune ex Gordon) and the Otska hydrangea (named after Siebold's familiar name for his Japanese sweetheart). Numerous species epithets commemorate him, including many ornamental plants and Japanese trees, e.g. Magnolia sieboldii K.Koch, Tsuga sieboldii Carrière, Clematis sieboldii D.Don, Primula sieboldii E.Morren, Sedum sieboldii Hort. ex G.Don, Viburnum sieboldii Miq. and Berberis sieboldii Miq.

Sources:
H. Körner, in D. von Pöllnitz (ed.), 1960, Lebenslaufe aus Franken, 6: 508-520
S. Kure, F.M. Trautz, edited by H. Walravens, 1996, Philipp Franz von Siebold: Leben und Werk
C.A.J.A. Oudemans, 1867, Gardeners' Chronicle, 1867(1): 76
E. Regel, 1867, Gartenflora, 16: 27-30.