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The birthplace of modern botany in Japan

October 1, 2021

The majestic ginkgo standing near the center of the Koishikawa Botanical Garden. By studying this tree, Sakugoro Hirase discovered that the ginkgo produces sperm.

The main botanical garden of the Graduate School of Science is situated in Koishikawa, a district neighboring the university’s Hongo Campus. This place, commonly known as Koishikawa Botanical Garden and designated as a Historic Site and Place of Scenic Beauty in Japan, is in essence a facility to promote botanical research and education.

Koishikawa Botanical Garden is Japan’s, and one of the world’s, oldest botanical gardens. Its history dates back to 1684 when its earliest predecessor, the Koishikawa Medicinal Herb Garden, was established by the Tokugawa shogunate. Upon the founding of the University of Tokyo in 1877, the garden became part of the university, and has been open to the public ever since.

The garden is topographically diverse, consisting of plateaus, slopes, and ponds, and has approximately 4,000 species of plants. Furthermore, the facility is visited by numerous botanists both in and outside the university who access its collection of more than 600,000 plant specimens and around 20,000 botany-related books.

Its satellite garden, called Nikko Botanical Garden, is located in Nikko, Tochigi Prefecture. It was created in 1902 for the purpose of research and education on mountain plants that are difficult to grow in Tokyo.

The Koishikawa Botanical Garden is also known as the birthplace of modern botany in Japan because the nation’s first epoch-making discovery in the history of global botany was made there, which was the 1896 discovery of sperm of a ginkgo tree by Sakugoro Hirase, an assistant professor of the Department of Botany at the School of Science.

As ginkgoes are gymnosperms, Hirase’s discovery has served as an important key to elucidating the evolutionary process of plants by linking mosses and ferns that produce sperm to angiosperms that do not.

This ginkgo tree still stands, alive and majestic, near the center of the garden. It is estimated to be 300 years old with a trunk circumference of 4.9 meters.

Interview and text: Masatsugu Kayahara

Originally published in The School of Science Brochure 2019



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