Involved with EC 2.1.1.76 quercetin 3-O-methyltransferase and EC 2.1.1.83 3,7-dimethylquercetin 4′-O-methyltransferase in the methylation of quercetin to 3,7,4′-trimethylquercetin in Chrysosplenium americanum. Does not act on flavones, dihydroflavonols, or their glucosides.