Saponin was found in all parts of the plant.
"Scientific American Supplement, No. 623, December 10, 1887" by Various
The saponins constitute a group of glucosides which are widely distributed in plants, whose properties have been known since early Grecian times.
"The Chemistry of Plant Life" by Roscoe Wilfred Thatcher
It gives no tannin or saponin tests.
"The Nature of Animal Light" by E. Newton Harvey
Anti-Wrinkle Activity of Hydroyzed Ginseng Saponins.
Anti-Wrinkle Activity of Hydroyzed Ginseng Saponins CosmeticsAndToiletries.com.
The reason for washing quinoa before cooking is to rinse off the saponins, which are a slightly soapy tasting phytochemical.