Saponarin is a flavoneglucoside. It is found in Saponaria officinalis and in Strongylodon macrobotrys where it imparts the characteristic jade color to the flower. This coloration has been shown to be an example of copigmentation, a result of the presence of malvin (an anthocyanin) and saponarin in the ratio 1:9. Under the alkaline conditions (pH 7.9) found in the sap of the epidermal cells, this combination produced a blue-green pigmentation; the pH of the colorless inner floral tissue was found to be lower, at pH 5.6. Experiments showed that saponarin produced a strong yellow colouring in slightly alkaline conditions, resulting in the greenish tone of the flower.[1] It is also found in passion flowers (Passiflora sp.).
References
^Greenish blue flower colour of Strongylodon macrobotrys. Kosaku Takeda, Aki Fujii, Yohko Senda and Tsukasa Iwashina, Biochemical Systematics and Ecology, Volume 38, Issue 4, August 2010, Pages 630–633, doi:10.1016/j.bse.2010.07.014