In the early years of the 20th century, color photography was not widely used, and botanists of the day were dependent on the time-consuming process of traditional botanical painting to illustrate their work. To document his Opuntia studies for the U.S.D.A., David Griffiths needed descriptive illustrations of his many specimens of cacti, but as this work was primarily a government project, he also needed to avoid the time-consuming process involved with preparing botanical paintings.

The solution was a process involving his vast collection of glass plate negatives whereby he would make very light photographic prints that L. C. C. Krieger would then paint with watercolor. This efficient method produced results that greatly enhanced both the realism of the original photograph and the depth and form of the watercolor painting.

Griffiths’ glass plate negatives of the Opuntia were used in this way by both Krieger and other illustrators whose tinted photographs can be found in The Cactaceae, which also contains traditional watercolor paintings of cacti, often showing both methods by different illustrators on a single plate.