[1] He studied botany under Harry Marshall Ward, Albert Seward and Frederick Blackman, graduating with First Class Honours.

[1] He was awarded the Frank Smart Studentship by Gonville and Caius College at the University of Cambridge, to which he transferred in June 1899.

[3] Yapp was appointed botanist to Cambridge University's 1899–1900 expedition to the North-Eastern Malay States, led by Walter William Skeat.

[1][3] Yapp was appointed as the University of Birmingham's Mason Professor of Botany in 1919, succeeding George Stephen West and overseeing the department's move from the city centre to the new campus at Edgbaston, with laboratories arranged to his design.

[11] By the time the new laboratories at Edgbaston were opened, in October 1927, Yapp was showing signs of ill health, and was soon unable to attend conferences.