[britishbryologicalsociety.org.uk] Description: This small liverwort grows in long-persistent rosettes or patches up to 15 mm across. Its thallus branches are up to 1.2 mm wide, dark green above with a bluish sheen, and with a deep, sharply defined median groove. Below the sharp thallus margins there is a line of dark purple or almost black ventral scales which become very conspicuous in dry conditions when the thallus margins inroll. Capsules are borne within older parts of the thallus. (link added by Mary Ann Machi)