Isolated from the plants Silene dioica (red campion) [1], Iris ensata (Japanese iris) [2] and Iris hollandica (Dutch iris) [3]. Also acts on the 3-O-rutinosides of pelargonidin, delphinidin and malvidin, but not the corresponding glucosides or 6-acylglucosides. The enzyme does not catalyse the glucosylation of the 5-hydroxy group of cyanidin 3-glucoside.