"Condensed tannins:
These tannins are resistant to hydrolysis and they derive from the flavonols, catechins and flavan-3, 4-diols. On treatment with acids or enzymes they are decomposed into phlobaphenes. On dry distillation condensed tannins produce catechol. These tannins are called *catechol tannins*. These tannins are found in cinchona bark, male fern, areca seeds, tea leaves and wild cherry bark, bahera fruits, Amla, etc.