In 1940, Robert F. Hoover, on his monograph of Chlorogalum, noted a division in the genus on the basis of diurnal and vespertine flowering species. He also noted that the same two diurnal species had similar floral morphology. He kept the genus whole on the basis that their vegetative morphology and geographic distribution was quite close and consistent.Hoover, R.F. 1940. A monograph of the genus Chlorogalum. Madroño 5: 137–147.
