The taxonomy of "Verbascum" has not undergone any significant revision since Svanve Mürbeck's monographies in the 1930s, with the exception of the work of Arthur Huber-Morath, who used informal group in organizing the genus for the florae of Iran and Turkey to account for many intermediate species. Since Huber-Morath's groups are not taxonomical, Mürbeck's treatment is the most current one available, as no study has yet sought to apply genetic or molecular data extensively to the genus. In Mürbeck's classification, "V. thapsus" is placed in section "Bothrospermae" subsect. "Fasciculata" (or sect. "Verbascum" subsect. "Verbascum" depending on nomenclatural choices) alongside species such as "Verbascum nigrum" (black or dark mullein), "Verbascum lychnitis" (white mullein) and "Verbascum sinuatum" (wavy-leaved mullein).