Photo courtesy of jedmar
Nursery in Erfurt, Germany. See also J. C. Schmidt under Breeders.
The rose colour codes in the 1933 catalogue are based on the work of
- Prof. Wilhelm Ostwald (1853-1932), Nobel prize for chemistry in 1909, who published works on colour standards in 1916/17
- Prof. Franz August Otto Krüger (1868-1938), who further refined the Ostwald scales
- Ernst Benary, seed trader
The colours and tones could be measured with a Zeiss instrument. See also the article "Eine Farbenordnung für Rosen" by Brigitte Wachsmuth (with link to the article).