Why does fresh Burdock tea turn green?

I noticed this phenomenon in my burdock tea, so I did a little research and tracked down the answer- anthocyans! Many of these pigments found naturally in certain plants are pH indicators. They will manifest a blue-green hue in alkaline environments, and purple-red in acidic conditions.

Next time you make burdock tea, try an experiment. Make a about a half cup of a strong root decoction and let it cool fully. If your water, like mine, is alkaline, you'll get an emerald-green tea. Put it in a transparent container. Now slowly add full-strength (5% acidity) white vinegar. The tea will turn pale purple right before your eyes.