This pair of fine prints is an excellent example of how hand coloring can vary from one print to another – both are based on a fine painting, a copy of which was then engraved on a copper plate and then printed in black and white (note the clear “plate impression” in the prints above, made when the copper plate was pressed firmly onto the paper). Colorists then added the color, painstakingly painting each print — but different colorists sometimes used different shades, and seldom had the benefit of seeing the original plant or even the original painting. It’s possible to see other differences — note that the stripes on the flowers have a slightly different pattern on the two prints.
The lighter print, to the left, is closer to real life; it’s possible that the pigments have oxidized in the one to the right, darkening as a function of age — but note that the underside of the leaf is a lighter color.
Another print of the same subject can be seen here.