This paper examines the role played by the Arnold Arboretum of Harvard University in training the first generation of modern Chinese botanists and supporting them to do field work and develop herbarium collections in China. It highlights the scientific career of H.H. Hu, who received his doctorate from Harvard University in 1925 and was strongly influenced by Arnold Arboretum staff members, including C.S. Sargent, Alfred Rehder, J.G. Jack and E.D. Merrill. The paper discusses the role of the Arnold Arboretum in the initial, worldwide distribution of Metasequoia glyptostroboides seed in 1948, and features photographs and measurements of notable specimens growing at the Arboretum today.