Mr. Burbank's Original Yellow Calla
The plant from which this flower was developed is of African origin. It is a not distant relative of the familiar White Calla, belonging to the Genus Richardia. These plants, although universally called Callas by the florist, are not so named by the botanist, the true Calla being a quite different flower of no great horticultural importance. The Yellow Calla, known also as the Pride of the Congo, was originally of a greenish yellow color, but has been made to take on the rich hues above shown by selective breeding.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 2 Chapter 3