Cinchonine is an alkaloid found in "Cinchona officinalis". Cinchonidine is an alkaloid found in "Cinchona officinalis" and "Gongronema latifolium". Cinchona officinalis is a South American tree in the family Rubiaceae. The species he described, "Cinchona officinalis", was, however, found to be of little therapeutic value. The quinine bark tree ("Cinchona officinalis") contains bitter substances to make the bark unpalatable.