The confusing publication history of the name Mentzelia arborescens Urban & Gilg is clarified. The first publication of the name by I. Urban in 1892 referred only to a floral diagram and should not be considered as valid publication. Subsequently, the name was taken up by E. Gilg in 1893 in Die natürlichen Pflanzenfamilien and described in detail as the only representative of the newly described Mentzelia L. sect. Dendromentzelia Urban & Gilg. This should be considered as the valid publication of the name. The material seen by the authors, however, was not cited in publication until 1900. A search for the original material led to the discovery of two Karwinski specimens in the Munich herbarium (M), which bear handwritten labels by Urban and Gilg dated 1892, and are therefore suitable as lectotypes of the name. One of them is here formally designated as the lectotype.