Color Code Y4 (Yellow bicolors, 1949 revision) under construction
Historic Irises assigned the Code Code Y4 are in the following Gallery below and those lacking images are in the list following the gallery. Originally Yellow bicolors were Y3 (yellow-toned, Y6 (blue-toned), and Y9 (red-toned) in the 1939 checklists but the 1949 revision referred all yellow bicolors registered after 1940 to Y1