Collections of Aloe L. (Asphodelaceae subfam. Alooideae) made by Friedrich Wilms (1848–1919) are analysed. The identity of material described as Aloe wilmsii Diels ex Hausen about 120 years ago is clarified. This long-overlooked name belongs in the synonymy of Aloe arborescens Mill. The original specimens, also collected by Wilms, on which the names A. affinis A.Berger and A. cinnabarina Diels ex A.Berger are based, are discussed. Lectotypes are designated for A. wilmsii, A. affinis, and A. cinnabarina. Biographical information is provided on Wilms who is commemorated in the specific epithet of Aloe wilmsii.