 The decoction is highly mucilaginous.The tincture reddens infusion of litmus, and precipitates on the addition of water.The official contrayerva root or "radix contrayervae" in 18th century English medical literature was "Dorstenia contrajerva", but the roots of other "Dorstenia" species such as the closely related "Dorstenia drakena"and "Dorstenia brasiliensis" were also often collected and sold.