Hayata undertook a botanical expedition to Tonkin in 1917, and was promoted to Associate Professor of the University of Tokyo in 1919.

In 1922, he was promoted to a full professorship as the third Professor of Systematic Botany at the University of Tokyo after the departure of Matsumura.

[1] Hayata described a total of over 1,600 different taxa, most of which are from Taiwan, but also include plants from Japan, China and Vietnam.

In 1920, the Imperial Academy of Japan awarded Hayata the Prince Katsura Commemoration Prize for his contribution to the flora of Formosa.

[1] Hayata's publications cover a period of more than 30 years, during which he authored more than 150 scientific articles and books.